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Liao Y, Lan Q. Understanding the Impact of Chain Mobility on Conformational Evolution and Kinetics of Mesophase Formation in Poly(ʟ-lactide) under Low-Pressure CO 2. Polymers (Basel) 2024; 16:1378. [PMID: 38794571 PMCID: PMC11124961 DOI: 10.3390/polym16101378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 05/03/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Although the mesomorphic phase as an intermediate state has been introduced to understand polymer crystallization, the understanding of the mesomorphic phase is far from complete. Here, the effect of chain mobility on the mesophase structuring in melt-quenched poly(ʟ-lactide) (PLLA) treated in low-pressure CO2 at 1.6-2.0 MPa and 0 °C was investigated using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and atomic force microscopy (AFM). The IR and AFM results demonstrated that the final degree of order and the kinetics of structural evolution during the CO2-induced mesophase formation were critically dependent on the CO2 pressure. This was attributed to the distinct dynamics of conformational evolution (gg to gt conformer transition) due to the different CO2 pressures. The thermal behavior from the DSC results showed that CO2 pressure dominated both the scale and dynamics of the chain motion of PLLA. At a lower CO2 pressure of 1.6 MPa, smaller-scale segmental motion was not replaced by the larger-scale cooperative motion that occurred at a relatively higher CO2 pressure of 2 MPa, which was favorable for faster mesophase formation. Consequently, by inhibiting direct crystallization under limited mobility conditions, it was demonstrated that different chain mobility controlled by CO2 pressure and thus CO2 solubility impacted the dynamics of the mesophase formation of PLLA. The present results have implications for understanding the role of chain mobility in determining the intermediate structural phases in semicrystalline polymers.
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Affiliation(s)
| | - Qiaofeng Lan
- Biomaterials Research Center, School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China;
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2
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Jia DZ, Ma GQ, Liu Q, Zhang J, Li JQ, Lin H, Li XJ, Zhong GJ, Li ZM. Extensional Stress-Induced Ductility of Poly(l-lactide) Films: Role of the Entangled Network in Amorphous Regions. Biomacromolecules 2023. [PMID: 37276461 DOI: 10.1021/acs.biomac.3c00188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The relationship between the density of the entangled amorphous network and the ductility of oriented poly(l-lactide) (PLLA) films is explored based on the preferential hydrolysis of the amorphous regions in phosphate buffer solution (PBS). PLLA films with a balance of ductility and stiffness have been prepared by the "casting-annealing stretching" based on mechanical rejuvenation, and the structural evolution and mechanical properties at different hydrolysis durations have been identified. Various stages are found during the transition of ductility to brittleness for hydrolyzed PLLA films. First, the elongation at break for hydrolyzed PLLA films remains unchanged in the first stage of hydrolysis and then gradually decreases. Eventually, the films turn to be brittle in the third stage. The strain-hardening modulus (GR) of the hydrolyzed films is utilized to reflect the density of the entangled amorphous network, and a gradual decrease of GR with hydrolysis time indicates the decisive role of the amorphous entanglement network in the mechanical rejuvenation-induced ductility of PLLA. The quantitative relationship between the entangled amorphous network and the stress-induced ductility of PLLA films is revealed. The dependence of deformation behavior on entangled amorphous network density is closely correlated to activated primary structure during deformation. The intact chain network plays a crucial role in sufficiently activating the primary structure to yield and disentanglement during the subsequent necking. These findings could advance the understanding of the PLLA's ductility induced by mechanical rejuvenation and offer guidance for awakening the intrinsic toughness of PLLA.
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Affiliation(s)
- De-Zhuang Jia
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Guo-Qi Ma
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Qian Liu
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Jie Zhang
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Jia-Qi Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Hao Lin
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Xu-Juan Li
- School of Environment and Resource, Southwest University of Science and Technology, Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Sichuan Engineering Lab of Non-Metallic Mineral Powder Modification & High-Value Utilization, Mianyang 621010, China
| | - Gan-Ji Zhong
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Zhong-Ming Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
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3
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Cai Y, Liu S, Fang C, Liu Z, He Y, Qu JP. Strengthening-toughening pure poly(lactic acid) with ultra-transparency through increasing mesophase promoted by elongational flow field. Int J Biol Macromol 2023:125091. [PMID: 37247709 DOI: 10.1016/j.ijbiomac.2023.125091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/15/2023] [Accepted: 05/23/2023] [Indexed: 05/31/2023]
Abstract
Poly(lactic acid) (PLA), as a biodegradable material, finds wide applications in packaging, automotive, and biological industries. However, achieving high strength, toughness, ultra-transparency, and heat resistance simultaneously in pure PLA through continuous one-step manufacturing remains a significant challenge. In this study, we addressed this challenge by utilizing the eccentric rotor extruder (ERE) in combination with cooling rolls to manufacture PLA sheets with outstanding mechanical performance. The ERE's elongational flow field combined with the cooling roller's weak stretching action induced orientation in the PLA molecular chains and promoted the formation of more mesophase, significantly improving mechanical properties. When the extrusion-stretch ratio (λ) value was 3.5, the tensile yield strength, Young's modulus, and elongation at break of ERE-fabricated samples ER-3.5 reached 86.2 MPa, 1777 MPa, and 57.9 %, respectively. Compared to the SE-3.5 samples manufactured with traditional methods, the increases were 38.8 %, 25.8 %, and 9.4 times, respectively. Additionally, the ERE manufactured samples maintained ultra-transparency and high heat resistance, making them suitable for food packaging, biomedicine, and other related fields. This methodology provides an efficient industrial-scale approach for manufacturing neat, biodegradable PLA with outstanding mechanical performance and ultra-transparency.
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Affiliation(s)
- Yu Cai
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Shuai Liu
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Cong Fang
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Zhihua Liu
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Yue He
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China.
| | - Jin-Ping Qu
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China.
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4
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Robust Poly(glycolic acid) Films with Crystal Orientation and Reinforcement of Chain Entanglement Network. CHINESE JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1007/s10118-023-2894-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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5
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Niu D, Xu P, Li J, Yang W, Liu T, Ma P. Strong, ductile and durable Poly(glycolic acid)-based films by constructing crystalline orientation, entanglement network and rigid amorphous fraction. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Huang A, Song X, Liu F, Wang H, Geng L, Chen B, Peng X, Wang Z, Tian G. Facile preparation of anisotropic
PLA
/
CNT
nanocomposites by hot and cold rolling processes for improving mechanical and conductive properties. J Appl Polym Sci 2022. [DOI: 10.1002/app.52789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- An Huang
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Xincheng Song
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Fan Liu
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Haokun Wang
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Lihong Geng
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Binyi Chen
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Xiangfang Peng
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Zhen Wang
- Key Laboratory of Polymer Materials and Products, School of Materials Science and Engineering Fujian University of Technology Fuzhou China
| | - Genlin Tian
- Department of Biomaterials International Center for Bamboo and Rattan Beijing China
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7
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Chao YK, Praveena NM, Yang KC, Gowd EB, Ho RM. Crystallization of polylactides examined by vibrational circular dichroism of intra- and inter-chain chiral interactions. SOFT MATTER 2022; 18:2722-2725. [PMID: 35234247 DOI: 10.1039/d2sm00060a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Herein, vibrational circular dichroism (VCD) measurements were carried out to study the kinetics of cold-crystallized poly(D-lactide) (PDLA) at the molecular level via qualitative analysis. The amplification of the VCD signals from intra- and inter-chain chiral interactions suggests the formation of partially ordered PDLA, followed by heterogeneous nucleation for crystallization. These results were further supported by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR) spectroscopy analyses.
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Affiliation(s)
- Yi-Kuan Chao
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China.
| | - N M Praveena
- Materials Science and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Industrial Estate (P.O.) Pappanamcode, Trivandrum 695 019, Kerala, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Kai-Chieh Yang
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China.
| | - E Bhoje Gowd
- Materials Science and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Industrial Estate (P.O.) Pappanamcode, Trivandrum 695 019, Kerala, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Rong-Ming Ho
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China.
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8
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Janeczek H, Duale K, Sikorska W, Godzierz M, Kordyka A, Marcinkowski A, Hercog A, Musioł M, Kowalczuk M, Christova D, Rydz J. Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture. ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2022; 10:3323-3334. [PMID: 35310687 PMCID: PMC8924921 DOI: 10.1021/acssuschemeng.1c08282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/18/2022] [Indexed: 05/13/2023]
Abstract
This paper presents the liquid crystal (LC) properties of poly(l-lactide) (PLLA). Mesophase behavior is investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The performed analyses confirm that pressed PLLA films exhibit the unique capability of self-assembling into a nematic mesophase under the influence of mechanical pressure, temperature, and time. It was originally demonstrated that the chiral nematic mesophase can be obtained by introducing fine powders into the polymer. Based on the research conducted, it was proved that the pressed PLLA films have a chiral nematic mesophase with a nematic-to-isotropic phase transition and a large mesophase stability range overlapping the temperature of the human body, which can persist for years at ambient temperature. The obtained films show tailor-made properties toward a nematic mesophase with a specific texture, including colored planar texture of the chiral nematic mesophase and blue-phase (BP) LC texture. The BP, described for the first time in plain PLLA, occurred over a wider than usual temperature range of stability between isotropic and chiral nematic thermotropic phases (ΔT ≈ 9 °C), which is an advantage of the obtained polymer material, in addition to ease of preparation. This opens up new prospects for advanced photonic green applications.
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Affiliation(s)
- Henryk Janeczek
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Khadar Duale
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Wanda Sikorska
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Marcin Godzierz
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Aleksandra Kordyka
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Andrzej Marcinkowski
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Anna Hercog
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Marta Musioł
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
| | - Marek Kowalczuk
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
- School
of Science, Faculty of Science and Engineering, University of Wolverhampton, Wulfruna St., Wolverhampton WV1 1LY, U.K.
| | - Darinka Christova
- Institute
of Polymers, Bulgarian Academy of Sciences, Akad. Georgi Bonchev Str., Bl. 103A, 1113 Sofia, Bulgaria
| | - Joanna Rydz
- Centre
of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34, 41-800 Zabrze, Poland
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9
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Infrared bands to distinguish amorphous, meso and crystalline phases of poly(lactide)s: Crystallization and phase transition pathways of amorphous, meso and co-crystal phases of poly(ʟ-lactide) in the heating process. POLYMER 2022. [DOI: 10.1016/j.polymer.2021.124495] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Xu S, Zhou J, Pan P. Structural Evolutions of Initially Amorphous Polymers during Near‐
T
g
Stretching: A Minireview of Recent Progresses. MACROMOL CHEM PHYS 2021. [DOI: 10.1002/macp.202100427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Shanshan Xu
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University 38 Zheda Road Hangzhou 310027 China
| | - Jian Zhou
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University 38 Zheda Road Hangzhou 310027 China
- Institute of Zhejiang University‐Quzhou 78 Jiuhua Boulevard North Quzhou 324000 China
| | - Pengju Pan
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University 38 Zheda Road Hangzhou 310027 China
- Institute of Zhejiang University‐Quzhou 78 Jiuhua Boulevard North Quzhou 324000 China
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11
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Wang J, Bao J, Zhou J, Li X, Zhang X, Chen W. Effects of physical aging on the self‐healing, shape memory, and crystallization behaviors of hydrogen‐bonded supramolecular polymers. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jiantao Wang
- School of Materials Science and Engineering Zhejiang Sci‐Tech University Hangzhou China
| | - Jianna Bao
- School of Materials Science and Engineering Zhejiang Sci‐Tech University Hangzhou China
| | - Jiale Zhou
- School of Materials Science and Engineering Zhejiang Sci‐Tech University Hangzhou China
| | - Xiang Li
- School of Materials Science and Engineering Zhejiang Sci‐Tech University Hangzhou China
| | - Xianming Zhang
- School of Materials Science and Engineering Zhejiang Sci‐Tech University Hangzhou China
| | - Wenxing Chen
- School of Materials Science and Engineering Zhejiang Sci‐Tech University Hangzhou China
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12
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Zhang L, Zhao G, Wang G. Investigation on the α/δ Crystal Transition of Poly(l-lactic Acid) with Different Molecular Weights. Polymers (Basel) 2021; 13:3280. [PMID: 34641096 PMCID: PMC8512007 DOI: 10.3390/polym13193280] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 11/16/2022] Open
Abstract
Poly(l-lactic acid) (PLLA) crystal possesses a complex polymorphism, and the formation mechanism of various crystal forms has been a hot research topic in the field of polymer condensate matter. In this research, five kinds of PLLA with different molecular weights were prepared by ring-opening polymerization with strict dehydration operations and multistep purification treatments. Then, thin film isothermal crystallization experiments were carried out to obtain crystallized samples. Previous research has proven that the PLLA α crystal form is usually formed at a temperature above 120 °C and the PLLA δ (or α') crystal form is usually formed at a temperature below 120 °C. However, in this research, the characterization results indicated that the PLLA crystal changed from δ form to α form with the decrease of molecular weight at a temperature of 80 °C. Considering the molecular weight effect, the paper argued that the transitions of the α/δ crystal form are not only associated with temperature, but also related to entanglement state before crystallization. The small-angle X-ray scattering of the PLLA crystal and rheology analysis of the PLLA melt before crystallization further proved the significant role of entanglement. Finally, we tentatively proposed the entanglement effect mechanism on the transitions of the α/δ crystal form.
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Affiliation(s)
| | - Guoqun Zhao
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061, China; (L.Z.); (G.W.)
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13
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14
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Wang F, Liu H, Li Y, Li Y, Ma Q, Zhang J, Hu X. Tunable Biodegradable Polylactide-Silk Fibroin Scaffolds Fabricated by a Solvent-Free Pressure-Controllable Foaming Technology. ACS APPLIED BIO MATERIALS 2020; 3:8795-8807. [PMID: 35019555 DOI: 10.1021/acsabm.0c01157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Polylactide (PLA) and silk fibroin (SF) are biocompatible green macromolecular materials with tunable structures and properties. In this study, microporous PLA/SF composites were fabricated under different pressures by a green solid solvent-free foaming technology. Scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric (TG) analysis, and Fourier transform infrared (FTIR) spectroscopy were used to analyze the morphology, structure, and mechanical properties of the PLA/SF scaffolds. The crystalline, mobile amorphous phases and rigid amorphous phases in PLA/SF composites were calculated to further understand their structure-property relations. It was found that an increase in pore density and a decrease in pore size can be achieved by increasing the saturation pressure during the foaming process. In addition, changes in the microcellular structure provided PLA/SF scaffolds with better thermal stability, tunable biodegradation rates, and mechanical properties. FTIR and XRD analysis indicated strong hydrogen bonds were formed between PLA and SF molecules, which can be tuned by changing the foaming pressure. The composite scaffolds have good cell compatibility and are conducive to cell adhesion and growth, suggesting that PLA/SF microporous scaffolds could be used as three-dimensional (3-D) biomaterials with a wide range of applications.
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Affiliation(s)
- Fang Wang
- Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023, P. R. China.,School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Hao Liu
- Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023, P. R. China.,School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Yingying Li
- Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023, P. R. China.,School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Yajuan Li
- School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Qingyu Ma
- School of Physics and Technology, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Jun Zhang
- School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Xiao Hu
- Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey 08028, United States.,Department of Biomedical Engineering, Rowan University, Glassboro, New Jersey 08028, United States.,Department of Molecular and Cellular Biosciences, Rowan University, Glassboro, New Jersey 08028, United States
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15
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Sun Z, Wang L, Zhou J, Fan X, Xie H, Zhang H, Zhang G, Shi X. Influence of Polylactide (PLA) Stereocomplexation on the Microstructure of PLA/PBS Blends and the Cell Morphology of Their Microcellular Foams. Polymers (Basel) 2020; 12:polym12102362. [PMID: 33076235 PMCID: PMC7602427 DOI: 10.3390/polym12102362] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 11/27/2022] Open
Abstract
Polylactide foaming materials with promising biocompatibility balance the lightweight and mechanical properties well, and thus they can be desirable candidates for biological scaffolds used in tissue engineering. However, the cells are likely to coalesce and collapse during the foaming process of polylactide (PLA) due to its intrinsic low melt strength. This work introduces a unique PLA stereocomplexation into the microcellular foaming of poly (l-lactide)/poly (butylene succinate) (PLLA/PBS) based on supercritical carbon dioxide. The rheological properties of PLA/PBS with 5 wt% or 10 wt% poly (d-lactide) (PDLA) present enhanced melt strength owing to the formation of PLA stereocomplex crystals (sc-PLA), which act as physical pseudo-cross-link points in the molten blends by virtue of the strong intermolecular interaction between PLLA and the added PDLA. Notably, the introduction of either PBS or PDLA into the PLLA matrix could enhance its crystallization, while introducing both in the blend triggers a decreasing trend in the PLA crystallinity, which it is believed occurs due to the constrained molecular chain mobility by formed sc-PLA. Nevertheless, the enhanced melt strength and decreased crystallinity of PLA/PBS/PDLA blends are favorable for the microcellular foaming behavior, which enhanced the cell stability and provided amorphous regions for gas adsorption and homogeneous nucleation of PLLA cells, respectively. Furthermore, although the microstructure of PLA/PBS presents immiscible sea-island morphology, the miscibility was improved while the PBS domains were also refined by the introduction of PDLA. Overall, with the addition of PDLA into PLA/10PBS blends, the microcellular average cell size decreased from 3.21 to 0.66 μm with highest cell density of 2.23 × 1010 cells cm−3 achieved, confirming a stable growth of cells was achieved and more cell nucleation sites were initiated on the heterogeneous interface.
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Affiliation(s)
- Zhiyuan Sun
- Queen Mary University of London Engineering School, Northwestern Polytechnical University, Xi’an 710129, China; (Z.S.); (J.Z.)
- NPU-QMUL Joint Research Institute of Advanced Materials and Structures, Northwestern Polytechnical University, Xi’an 710072, China; (L.W.); (X.F.); (H.X.); (H.Z.)
| | - Long Wang
- NPU-QMUL Joint Research Institute of Advanced Materials and Structures, Northwestern Polytechnical University, Xi’an 710072, China; (L.W.); (X.F.); (H.X.); (H.Z.)
- School of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Macromolecular Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
| | - Jinyang Zhou
- Queen Mary University of London Engineering School, Northwestern Polytechnical University, Xi’an 710129, China; (Z.S.); (J.Z.)
- NPU-QMUL Joint Research Institute of Advanced Materials and Structures, Northwestern Polytechnical University, Xi’an 710072, China; (L.W.); (X.F.); (H.X.); (H.Z.)
| | - Xun Fan
- NPU-QMUL Joint Research Institute of Advanced Materials and Structures, Northwestern Polytechnical University, Xi’an 710072, China; (L.W.); (X.F.); (H.X.); (H.Z.)
- School of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Macromolecular Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
| | - Hanghai Xie
- NPU-QMUL Joint Research Institute of Advanced Materials and Structures, Northwestern Polytechnical University, Xi’an 710072, China; (L.W.); (X.F.); (H.X.); (H.Z.)
- School of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Macromolecular Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
| | - Han Zhang
- NPU-QMUL Joint Research Institute of Advanced Materials and Structures, Northwestern Polytechnical University, Xi’an 710072, China; (L.W.); (X.F.); (H.X.); (H.Z.)
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Guangcheng Zhang
- School of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Macromolecular Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
- Correspondence: (G.Z.); (X.S.)
| | - Xuetao Shi
- Queen Mary University of London Engineering School, Northwestern Polytechnical University, Xi’an 710129, China; (Z.S.); (J.Z.)
- NPU-QMUL Joint Research Institute of Advanced Materials and Structures, Northwestern Polytechnical University, Xi’an 710072, China; (L.W.); (X.F.); (H.X.); (H.Z.)
- School of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Macromolecular Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
- Correspondence: (G.Z.); (X.S.)
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16
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Temperature-dependent Crystallization and Phase Transition of Poly(L-lactic acid)/CO2 Complex Crystals. CHINESE JOURNAL OF POLYMER SCIENCE 2020. [DOI: 10.1007/s10118-021-2502-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Zheng Y, Pan P. Crystallization of biodegradable and biobased polyesters: Polymorphism, cocrystallization, and structure-property relationship. Prog Polym Sci 2020. [DOI: 10.1016/j.progpolymsci.2020.101291] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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18
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Wang Z, Zhang C, Zhang Z, Chen X, Wang X, Wen M, Chen B, Cao W, Liu C. Polyethylene oxide enhances the ductility and toughness of polylactic acid: the role of mesophase. SOFT MATTER 2020; 16:7018-7032. [PMID: 32648874 DOI: 10.1039/d0sm00671h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A lack of understanding of the structure-property relationship of the polylactic acid (PLA)-based polymer composite system makes it a challenge to manufacture products with optimized mechanical performance by precisely regulating the microscopic structure and morphology. Herein, we chose the PLA/polyethylene oxide (PEO) blend as a model to investigate the structural reason for the enhanced ductility and toughness of this kind of material. We have demonstrated that a considerable amount of the PLA mesophases exist in the melt quenched films that display high ductility and toughness, in contrast to the PLA crystals in their counterparts of slowly cooled films that are dominated by brittle fracture. The mesophase formed by melt quenching is attributed to a moderate acceleration of PLA chain mobility due to the plasticizing effect of the flexible PEO. In situ experiments have revealed the further formation of oriented mesophases induced by tensile deformation, which presents a high consistency between the content increase and the tensile stress intensification. We illustrate that the mesophases directly develop into a microfibrillar morphology to transmit the external stress and prevent crack propagation under deformation. This work emphasizes the essential role of the PLA mesophase in acquiring the enhanced ductility and toughness of the PLA/PEO composite films, which may be generalized to other similar PLA-based polymer composite materials.
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Affiliation(s)
- Zhen Wang
- National Engineering Research Center for Advanced Polymer Processing Technology, Key Laboratory of Materials Processing and Mold (Zhengzhou University), Ministry of Education, Zhengzhou University, Zhengzhou, 450002, China.
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19
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Sun ZB, Wei QY, Xie XL, Xu L, Ji X, Zhou L, Zhong GJ, Li ZM. Spatial dependence of ordering process in bulk materials of polylactide and its multiple system during hygrothermal aging. Polym Degrad Stab 2020. [DOI: 10.1016/j.polymdegradstab.2020.109107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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21
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Xie Q, Han L, Zhou J, Shan G, Bao Y, Pan P. Homocrystalline mesophase formation and multistage structural transitions in stereocomplexable racemic blends of block copolymers. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122180] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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22
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Li S, Chen T, Liao X, Han W, Yan Z, Li J, Li G. Effect of Macromolecular Chain Movement and the Interchain Interaction on Crystalline Nucleation and Spherulite Growth of Polylactic Acid under High-Pressure CO2. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01601] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Shaojie Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Taoyi Chen
- Jiaxiang Foreign Language School, Attached to Chengdu No. 7 Middle School, Chengdu, Sichuan 610023, China
| | - Xia Liao
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
- Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510641, China
| | - Weiqiang Han
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Zhihui Yan
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Junsong Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Guangxian Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
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23
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Strong and ductile poly (lactic acid) achieved by carbon dioxide treatment at room temperature. J CO2 UTIL 2019. [DOI: 10.1016/j.jcou.2019.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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24
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Morel A, Oberle SC, Ulrich S, Yazgan G, Spano F, Ferguson SJ, Fortunato G, Rossi RM. Revealing non-crystalline polymer superstructures within electrospun fibers through solvent-induced phase rearrangements. NANOSCALE 2019; 11:16788-16800. [PMID: 31465059 DOI: 10.1039/c9nr04432a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The design of nanofibers for biomedical applications requires a deep understanding of the fiber formation process and the resulting internal structure. In this regard, non-crystalline, mesomorphic structures play a central role in the processing of many polymers as precursors in the formation of crystalline superstructures (e.g. shish-kebab) and influence strongly the physical properties of polymers with a low degree of crystallinity. Yet, our ability to probe these relevant features is often greatly limited by their low contrast differences with the amorphous phase. We present an approach to reveal the organization of the mesomorphic superstructures within such polymeric materials, on the example of electrospun poly(l-lactide) nanofibers. Based on solvent-induced crystallization, this method employs fine-tuned solvent/non-solvent systems to enhance the contrast of these structural features by selectively triggering and controlling reorganization of the phases. Hereby, the mesomorphic regions are transformed into an α-crystalline phase, while the nanoscale spatial arrangement of the underlying superstructures is preserved. Combined with X-ray analytical techniques and electron microscopy, our approach provides detailed insights into the nanofiber's inner architecture, allowing for its direct visualization. Thereby, the influence of electrospinning parameters on the fiber formation process is explained as well as the impact of the resulting non-crystalline superstructures on single fiber mechanical properties. The method can be applied to comparable polymers for the development of materials with controlled, tailored properties.
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Affiliation(s)
- Alexandre Morel
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, 9014 St Gallen, Switzerland.
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25
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Zhang L, Zhao G, Wang G. Investigation on the growth of snowflake-shaped Poly(l-Lactic acid) crystal by in-situ high-pressure microscope. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.05.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Zhang L, Zhao G, Wang G. Investigation of the influence of pressurized CO 2 on the crystal growth of poly(l-lactic acid) by using an in situ high-pressure optical system. SOFT MATTER 2019; 15:5714-5727. [PMID: 31265051 DOI: 10.1039/c9sm00737g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Since CO2 is a kind of nontoxic, non-flammable and biocompatible fluid, introducing CO2 in the PLLA formation process has been regarded as a green way to the manufacture of biological products or medical supplies. However, it is still a challenge to understand the influence of CO2 on the crystal growth behavior of PLLA. Here, we developed an in situ high-pressure observation system, composed of optics, polarization optics and a small angle laser scattering system, to record the growth process of PLLA crystals in a pressurized CO2 environment. It is found that, at a low temperature (near Tg), low pressure CO2 (0.5 MPa in this work) can still induce the formation of numerous micron-sized spherulites of PLLA. Therefore, the introduction of CO2 can significantly enhance the crystallization ability of PLLA and decrease the crystallization temperature, which is helpful in improving the mechanical properties of PLLA products. We also found that a snowflake-shaped crystal was assembled by rhombic lamellae under pressurized CO2. There is a melt accumulation zone surrounding the growth front of the snowflake-shaped crystal, indicating that the growth front nucleation is limited by the pressurized CO2. This melt accumulation zone is quite different from the melt depletion zone existing ahead of the reported dendritic crystal front. Interestingly, in a high-pressure CO2 environment, a kind of bamboo-like branch is formed in a rhythmic growth mode. The repeating unit of the bamboo-like branch is constructed by an asymmetric terrace crystal originated from screw dislocation in the melt accumulation zone. These results demonstrated that CO2 has a remarkable tunability on the polymer crystal morphology.
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Affiliation(s)
- Lei Zhang
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, Shandong 250061, P. R. China.
| | - Guoqun Zhao
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, Shandong 250061, P. R. China.
| | - Guilong Wang
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, Shandong 250061, P. R. China.
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27
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Gao XR, Li Y, Huang HD, Xu JZ, Xu L, Ji X, Zhong GJ, Li ZM. Extensional Stress-Induced Orientation and Crystallization can Regulate the Balance of Toughness and Stiffness of Polylactide Films: Interplay of Oriented Amorphous Chains and Crystallites. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00932] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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28
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Study on Phase Transformation Behavior of Strain-induced PLLA Mesophase by Polarized Infrared Spectroscopy. CHINESE JOURNAL OF POLYMER SCIENCE 2018. [DOI: 10.1007/s10118-019-2184-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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29
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Syazwan M, Sasaki T. Rapid crystallization and mesophase formation of poly(L-lactic acid) during precipitation from a solution. E-POLYMERS 2018. [DOI: 10.1515/epoly-2017-0247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractVery rapid crystallization behaviors of poly(L-lactic acid) (PLLA) are observed at room temperature when it is precipitated from a chloroform solution into a large amount of alcohols (non-solvents). The resulting crystalline phase contains both a highly ordered (α) and less ordered (α′) modifications, and the fraction of these phases depends on the alcohols used as the non-solvents: methanol tends to produce the highly ordered phase. The degree of crystallinity tends to be high for lower alcohols. When the precipitation occurs in n-hexane, almost no crystalline phase is formed, but a mesomorphic phase is formed as a precursor to the crystalline phase. The results suggest that the hydroxyl group of alcohols tends to promote the crystallization of PLLA. However, it is found that the precipitation in methanol at lower temperatures, such as 0°C, does not yield any crystalline phase. It is suggested that the present rapid crystallization during precipitation originates from the enhanced mobility of PLLA molecules in a metastable (non-equilibrium) liquid state.
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Affiliation(s)
- Muhammad Syazwan
- Department of Materials Science and Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910 8507, Japan
| | - Takashi Sasaki
- Department of Materials Science and Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910 8507, Japan
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30
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Lan Q, Yu J, Zhang J, He J. Nucleation Enhancement in Stereodefective Poly(l-lactide) by Free Volume Expansion Resulting from Low-Temperature Pressure CO₂ Preconditioning. Polymers (Basel) 2018; 10:E120. [PMID: 30966156 PMCID: PMC6415141 DOI: 10.3390/polym10020120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Revised: 01/15/2018] [Accepted: 01/24/2018] [Indexed: 11/16/2022] Open
Abstract
Nucleation enhancement in a highly stereodefective poly(l-lactide) (PLLA) with an optical purity of 88% by low-temperature pressure (0 and 35 °C under 2 MPa) CO₂ preconditioning was investigated using differential scanning calorimetry (DSC), infrared (IR) spectroscopy, polarized optical microscopy (POM) as well as positron annihilation lifetime spectroscopy (PALS). Despite the preconditioning of the melt-quenched films for 2 h, IR results indicated that no trace of mesophase was generated and the samples remained in the glassy state. However, judging from the results of DSC, IR, and POM, when compared to the untreated sample, both the treated ones showed a significantly enhanced crystal nucleation effect, resulting in the corresponding greatly enhanced crystallization kinetics. Moreover, owing to the existence of the retrograde vitrification, the conditions of the previous low-pressure CO₂ conditioning affected the nucleation enhancement effect. When compared to the case of 35 °C, the much lower temperature of 0 °C was more effective for nucleation enhancement. The PALS results indicated that the enlarged free volume, which resulted from the CO₂ conditioning, largely accounted for the formation of locally ordered structures, providing many more potential nucleation sites for forming critical nuclei and thus the resulting enhanced crystallization kinetics in glassy PLLA. The present results have implications in understanding the nucleation enhancement effect, in particular in stereodefective PLLA systems, which possess extremely low crystallization ability and are thus probably too problematic to be evaluated by conventional methods.
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Affiliation(s)
- Qiaofeng Lan
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China.
| | - Jian Yu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China.
| | - Jun Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China.
| | - Jiasong He
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China.
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31
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Lv R, Peng N, Jin T, Na B, Wang J, Liu H. Stereocomplex mesophase and its phase transition in enantiomeric polylactides. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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32
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Nagarajan S, Deepthi K, Gowd EB. Structural evolution of poly(l-lactide) block upon heating of the glassy ABA triblock copolymers containing poly(l-lactide) A blocks. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.06.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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33
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Lan Q, Li Y. Mesophase-Mediated Crystallization of Poly(l-lactide): Deterministic Pathways to Nanostructured Morphology and Superstructure Control. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01442] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Qiaofeng Lan
- Ningbo Institute of Materials
Technology and Engineering, Chinese Academy of Sciences (CAS), Ningbo 315201, China
| | - Yong Li
- Ningbo Institute of Materials
Technology and Engineering, Chinese Academy of Sciences (CAS), Ningbo 315201, China
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34
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Lan Q, Yu J, Zhang J, He J. Direct formation of banded spherulites in poly(l-lactide) from the glassy state: Unexpected synergistic role of chain structure and compressed CO2. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.07.083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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