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dos Anjos EGR, Brazil TR, de Melo Morgado GF, Montagna LS, Braga NF, Antonelli E, Marini J, Rezende MC, Passador FR. Influence of MWCNT aspect ratio on the rheological, electrical, electromagnetic shielding, and mechanical properties of polycarbonate melt mixed nanocomposites. JOURNAL OF POLYMER RESEARCH 2023. [DOI: 10.1007/s10965-023-03453-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Influence of CNT Length on Dispersion, Localization, and Electrical Percolation in a Styrene-Butadiene-Based Star Block Copolymer. Polymers (Basel) 2022; 14:polym14132715. [PMID: 35808760 PMCID: PMC9268902 DOI: 10.3390/polym14132715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 06/23/2022] [Accepted: 06/28/2022] [Indexed: 02/04/2023] Open
Abstract
This study followed the approach of dispersing and localizing carbon nanotubes (CNTs) in nanostructured domains of block copolymers (BCPs) by shortening the CNTs via ball milling. The aim was to selectively tune the electrical and mechanical properties of the resulting nanocomposites, e.g., for use as sensor materials. Multiwalled carbon nanotubes (MWCNTs) were ground into different size fractions. The MWCNT length distribution was evaluated via transmission electron microscopy and dynamic light scattering. The nanostructure of the BCPs and the glass transition temperatures of the PB-rich and PS phases were not strongly affected by the addition of CNTs up to 2 wt%. However, AFM and TEM investigations indicated a partial localization of the shortened CNTs in the soft PB-rich phase or at the interface of the PB-rich and PS phase, respectively. The stress-strain behavior of the solution-mixed composites differed little from the mechanical property profile of the neat BCP and was largely independent of CNT amount and CNT size fraction. Significant changes could only be observed for Young’s modulus and strain at break and may be attributed to CNT localization and small changes in morphology. For nanocomposites with unmilled CNTs, the electrical percolation threshold was less than 0.1 wt%. As the CNTs were shortened, the resistivity increased and the percolation threshold shifted to higher CNT contents. Composites with CNTs ground for 7.5 h and 13.5 h showed no bulk conductivity but significantly decreased surface resistivity on the bottom side of the films, which could be attributed to a sedimentation process of the grind and thereby highly compressed CNT agglomerates during evaporation.
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Low-Cost and Highly Sensitive Pressure Sensor with Mold-Printed Multi-Walled Carbon Nanotubes Dispersed in Polydimethylsiloxane. SENSORS 2021; 21:s21155069. [PMID: 34372305 PMCID: PMC8347260 DOI: 10.3390/s21155069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/13/2021] [Accepted: 07/21/2021] [Indexed: 11/17/2022]
Abstract
Flexible pressure sensors with piezoresistive polymer composites can be integrated into elastomers to measure pressure changes in sealings, preemptively indicating a replacement is needed before any damage or leakage occurs. Integrating small percentages of high aspect ratio multi-walled carbon nanotubes (MWCNTs) into polymers does not significantly change its mechanical properties but highly affects its electrical properties. This research shows a pressure sensor based on homogeneous dispersed MWCNTs in polydimethylsiloxane with a high sensitivity region (0.13% kPa−1, 0–200 kPa) and sensitive up to 500 kPa. A new 3D-printed mold is developed to directly deposit the conductive polymer on the electrode structures, enabling sensor thicknesses as small as 100 μm.
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Caldas M, Santos AC, Rebelo R, Pereira I, Veiga F, Reis RL, Correlo VM. Electro-responsive controlled drug delivery from melanin nanoparticles. Int J Pharm 2020; 588:119773. [PMID: 32805382 DOI: 10.1016/j.ijpharm.2020.119773] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 01/18/2023]
Abstract
Electro-responsive controlled drug delivery has been receiving an increasing interest as one of the on-demand drug delivery systems, aiming the improvement of the therapeutics efficacy by controlling the amount of drug release at a specific time and target site. Herein, we report a simple method to develop an electro-responsive controlled drug delivery system using functionalized melanin nanoparticles (FMNPs) with polydopamine and polypyrrole to precisely control the release of dexamethasone (Dex). Optimized FMNPs showed 376.77 ± 62.05 nm of particle size, a polydispersity index of 0.26 ± 0.09 and a zeta-potential (ZP) of -32.59 ± 3.61 mV. FMNPs evidenced a spherical shape, which was confirmed by scanning electron microscopy. Fourier-transform infrared spectrometry analysis confirmed the deposition of the polymers on the FMNPs' surface. The incorporation efficiency of the optimized Dex-loaded FMNPs was 94.45 ± 0.63% and the increase of ZP to -40.34 ± 4.65 mV was attributed to the anionic nature of Dex. In vitro Dex release studies without stimuli revealed a maximum Dex release below 10%. Applying electrical stimulation, Dex release was augmented, with a maximum of ca. 32% after 24 h. The designed FMNPs provide a powerful biomaterial-based technological tool for electro-responsive controlled drug delivery, capable of surpassing the associated lack of efficiency and stability of current carriers.
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Affiliation(s)
- Mariana Caldas
- I3B's Research Institute on Biomaterials Biodegradables and Biomimetics, Universidade do Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Braga, Guimarães, Portugal
| | - Ana Cláudia Santos
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal; REQUIMTE/LAQV, Group of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
| | - Rita Rebelo
- I3B's Research Institute on Biomaterials Biodegradables and Biomimetics, Universidade do Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Braga, Guimarães, Portugal
| | - Irina Pereira
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal; REQUIMTE/LAQV, Group of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Francisco Veiga
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal; REQUIMTE/LAQV, Group of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Rui L Reis
- I3B's Research Institute on Biomaterials Biodegradables and Biomimetics, Universidade do Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Braga, Guimarães, Portugal; The Discoveries Centre for Regenerative and Precision Medicine, Headquarters at University of Minho, Barco, Guimarães, Portugal
| | - Vitor M Correlo
- I3B's Research Institute on Biomaterials Biodegradables and Biomimetics, Universidade do Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Braga, Guimarães, Portugal; The Discoveries Centre for Regenerative and Precision Medicine, Headquarters at University of Minho, Barco, Guimarães, Portugal
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Dispersion and Localization Behavior of Modified MWCNTs in Immiscible Polymer Blends of Polystyrene and Polybutadiene and in Corresponding Nanostructured Block Copolymers. JOURNAL OF COMPOSITES SCIENCE 2020. [DOI: 10.3390/jcs4020040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The influence of carbon nanotube (CNT) modification on the dispersion and localization behavior of the CNTs in immiscible blends of polystyrene (PS) and polybutadiene (PB), and in the nanostructured morphology of a star-shaped styrene-butadiene based block copolymer (BCP), was studied to form a basis for the development of functional materials with defined electrical property profiles. Unmodified multi-walled CNTs (MWCNTs) were dispersed in PS, PB and PS/PB blends by solution mixing. Additionally, MWCNTs were functionalized with n-octadecylamine and monoamino-terminated polystyrene to increase the compatibility between the homopolymers and the nanofiller. The MWCNT dispersion and the blend morphology formation were studied using transmission light microscopy and scanning electron microscopy. The MWCNT dispersion could be significantly improved by the modification of the MWCNTs. All MWCNT types were found to preferably localize in the PS phase of the PS/PB blend. However, only blends containing unmodified MWCNTs were electrically conductive. Similar effects were found in BCP/MWCNT composites. The BCP was already electrically conductive with a filler content of 0.1 wt % of unmodified MWCNTs. The stress–strain behavior of the BCP was slightly influenced by MWCNT addition and CNT modification. The dispersability of MWCNTs was significantly improved by CNT functionalization, which indicates a strong polymer-filler interaction.
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Staudinger U, Satapathy BK, Jehnichen D. Nanofiller Dispersion, Morphology, Mechanical Behavior, and Electrical Properties of Nanostructured Styrene-Butadiene-Based Triblock Copolymer/CNT Composites. Polymers (Basel) 2019; 11:E1831. [PMID: 31703362 PMCID: PMC6918330 DOI: 10.3390/polym11111831] [Citation(s) in RCA: 5] [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: 10/04/2019] [Revised: 10/30/2019] [Accepted: 11/06/2019] [Indexed: 11/16/2022] Open
Abstract
A nanostructured linear triblock copolymer based on styrene and butadiene with lamellar morphology is filled with multiwalled carbon nanotubes (MWCNTs) of up to 1 wt% by melt compounding. This study deals with the dispersability of the MWCNTs within the nanostructured matrix and its consequent impact on block copolymer (BCP) morphology, deformation behavior, and the electrical conductivity of composites. By adjusting the processing parameters during melt mixing, the dispersion of the MWCNTs within the BCP matrix are optimized. In this study, the morphology and glass transition temperatures (Tg) of the hard and soft phase are not significantly influenced by the incorporation of MWCNTs. However, processing-induced orientation effects of the BCP structure are reduced by the addition of MWCNT accompanied by a decrease in lamella size. The stress-strain behavior of the triblock copolymer/MWCNT composites indicate higher Young's modulus and pronounced yield point while retaining high ductility (strain at break ~ 400%). At a MWCNT content of 1 wt%, the nanocomposites are electrically conductive, exhibiting a volume resistivity below 3 × 103 Ω·cm. Accordingly, the study offers approaches for the development of mechanically flexible functional materials while maintaining a remarkable structural property profile.
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Affiliation(s)
- Ulrike Staudinger
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany;
| | - Bhabani K. Satapathy
- Department of Materials Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New-Delhi 110016, India;
| | - Dieter Jehnichen
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany;
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Taraghi I, Fereidoon A, Paszkiewicz S, Roslaniec Z. Electrically conductive polycarbonate/ethylene-propylene copolymer/multi-walled carbon nanotubes nanocomposites with improved mechanical properties. J Appl Polym Sci 2016. [DOI: 10.1002/app.44661] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Iman Taraghi
- Department of Mechanical Engineering; Semnan University; Semnan 35131-19111 Iran
- Institute of Material Science and Engineering; West Pomeranian University of Technology; Szczecin, Piastow Av. 19 PL-70310 Poland
| | | | - Sandra Paszkiewicz
- Institute of Material Science and Engineering; West Pomeranian University of Technology; Szczecin, Piastow Av. 19 PL-70310 Poland
| | - Zbigniew Roslaniec
- Institute of Material Science and Engineering; West Pomeranian University of Technology; Szczecin, Piastow Av. 19 PL-70310 Poland
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