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Hengsbach R, Fink G, Simon U. 1H-NMR studies on the volume phase transition of DNA-modified pNipmam microgels. SOFT MATTER 2024; 20:330-337. [PMID: 38087892 DOI: 10.1039/d3sm01124k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
DNA functionalized pNipmam microgels, which have recently been introduced, are examined at different concentrations of sodium chloride and in PBS solutions via temperature dependent 1H-NMR measurements and are compared to pure pNipmam microgels. We show that the DNA modification shifts the volume phase transition temperature towards lower temperatures and the addition of salt and PBS further supports this effect in both materials. Thermodynamic values, i.e. enthalpy, entropy and Gibbs free energy, are determined via a non-linear fit which can be applied directly to the measurement data without further linearization.
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Affiliation(s)
- Rebecca Hengsbach
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, D-52074 Aachen, Germany.
| | - Gerhard Fink
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, D-52074 Aachen, Germany.
| | - Ulrich Simon
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, D-52074 Aachen, Germany.
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2
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Lukáš Petrova S, Vragović M, Pavlova E, Černochová Z, Jäger A, Jäger E, Konefał R. Smart Poly(lactide)- b-poly(triethylene glycol methyl ether methacrylate) (PLA- b-PTEGMA) Block Copolymers: One-Pot Synthesis, Temperature Behavior, and Controlled Release of Paclitaxel. Pharmaceutics 2023; 15:pharmaceutics15041191. [PMID: 37111676 PMCID: PMC10143907 DOI: 10.3390/pharmaceutics15041191] [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: 03/08/2023] [Revised: 03/31/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
This paper introduces a new class of amphiphilic block copolymers created by combining two polymers: polylactic acid (PLA), a biocompatible and biodegradable hydrophobic polyester used for cargo encapsulation, and a hydrophilic polymer composed of oligo ethylene glycol chains (triethylene glycol methyl ether methacrylate, TEGMA), which provides stability and repellent properties with added thermo-responsiveness. The PLA-b-PTEGMA block copolymers were synthesized using ring-opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT) polymerization (ROP-RAFT), resulting in varying ratios between the hydrophobic and hydrophilic blocks. Standard techniques, such as size exclusion chromatography (SEC) and 1H NMR spectroscopy, were used to characterize the block copolymers, while 1H NMR spectroscopy, 2D nuclear Overhauser effect spectroscopy (NOESY), and dynamic light scattering (DLS) were used to analyze the effect of the hydrophobic PLA block on the LCST of the PTEGMA block in aqueous solutions. The results show that the LCST values for the block copolymers decreased with increasing PLA content in the copolymer. The selected block copolymer presented LCST transitions at physiologically relevant temperatures, making it suitable for manufacturing nanoparticles (NPs) and drug encapsulation-release of the chemotherapeutic paclitaxel (PTX) via temperature-triggered drug release mechanism. The drug release profile was found to be temperature-dependent, with PTX release being sustained at all tested conditions, but substantially accelerated at 37 and 40 °C compared to 25 °C. The NPs were stable under simulated physiological conditions. These findings demonstrate that the addition of hydrophobic monomers, such as PLA, can tune the LCST temperatures of thermo-responsive polymers, and that PLA-b-PTEGMA copolymers have great potential for use in drug and gene delivery systems via temperature-triggered drug release mechanisms in biomedicine applications.
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Affiliation(s)
- Svetlana Lukáš Petrova
- Institute of Macromolecular Chemistry CAS, Heyrovského nám. 2, 162 06 Prague, Czech Republic
| | - Martina Vragović
- Institute of Macromolecular Chemistry CAS, Heyrovského nám. 2, 162 06 Prague, Czech Republic
| | - Ewa Pavlova
- Institute of Macromolecular Chemistry CAS, Heyrovského nám. 2, 162 06 Prague, Czech Republic
| | - Zulfiya Černochová
- Institute of Macromolecular Chemistry CAS, Heyrovského nám. 2, 162 06 Prague, Czech Republic
| | - Alessandro Jäger
- Institute of Macromolecular Chemistry CAS, Heyrovského nám. 2, 162 06 Prague, Czech Republic
| | - Eliézer Jäger
- Institute of Macromolecular Chemistry CAS, Heyrovského nám. 2, 162 06 Prague, Czech Republic
| | - Rafał Konefał
- Institute of Macromolecular Chemistry CAS, Heyrovského nám. 2, 162 06 Prague, Czech Republic
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3
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Zheng SY, Li CY, Du M, Yin J, Qian J, Wu ZL, Zheng Q. Programmable Deformations of Biomimetic Composite Hydrogels Embedded with Printed Fibers. ACS APPLIED MATERIALS & INTERFACES 2020; 12:57497-57504. [PMID: 33319983 DOI: 10.1021/acsami.0c19656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Shape deformations are prevalent in nature, which are closely related to the heterogeneous structures with a feature of fibrous elements embedded in a matrix. The microfibers with specific orientations act as either passive geometrical constraints in an active matrix or active elements in a passive matrix, which generate programmed internal stresses and drive shape morphing under external stimuli. Morphing materials can be designed in a biomimetic way, yet it is challenging to fabricate composite hydrogels with well-distributed fibers by a facile strategy. Here, we demonstrate the fabrication of microfiber-embedded hydrogels facilitated by the extrusion-based printing technology. Programmed deformations are achieved in these hydrogels with microfibers distributed in the upper and/or bottom layers of the gel matrix. Under external stimuli, the microfibers and the gel matrix have different responses that produce internal stresses and result in programmable deformations of the composite gel. Multiple shape transformations are realized in the hydrogel by embedding multiple types of responsive microfibers in the passive or active matrix, which is fabricated with the assistance of multinozzle printing. A soft hook is designed to show the capacity of the composite hydrogel to hold and move an object in a saline solution. This facile and versatile strategy provides an alternative way to prepare biomimetic hydrogels with potential applications in biomedical devices, flexible electronics, and soft robots.
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Affiliation(s)
- Si Yu Zheng
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Chen Yu Li
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Miao Du
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jun Yin
- State Key Laboratory of Fluid Power and Mechatronic Systems, Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou 310028, China
| | - Jin Qian
- Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, China
| | - Zi Liang Wu
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Qiang Zheng
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
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4
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Konefał R, Spěváček J, Mužíková G, Laga R. Thermoresponsive behavior of poly(DEGMA)-based copolymers. NMR and dynamic light scattering study of aqueous solutions. Eur Polym J 2020. [DOI: 10.1016/j.eurpolymj.2020.109488] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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5
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Krakovský I, Kouřilová H, Hrubovský M, Labuta J, Hanyková L. Thermoresponsive double network hydrogels composed of poly(N-isopropylacrylamide) and polyacrylamide. Eur Polym J 2019. [DOI: 10.1016/j.eurpolymj.2019.04.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Velychkivska N, Starovoytova L, Březina V, Hanyková L, Hill JP, Labuta J. Improving the Colloidal Stability of Temperature-Sensitive Poly( N-isopropylacrylamide) Solutions Using Low Molecular Weight Hydrophobic Additives. ACS OMEGA 2018; 3:11865-11873. [PMID: 31459272 PMCID: PMC6645090 DOI: 10.1021/acsomega.8b01811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 09/11/2018] [Indexed: 06/10/2023]
Abstract
Poly(N-isopropylacrylamide) (PNIPAM) is an important polymer with stimuli-responsive properties, making it suitable for various uses. Phase behavior of the temperature-sensitive PNIPAM polymer in the presence of four low-molecular weight additives tert-butylamine (t-BuAM), tert-butyl alcohol (t-BuOH), tert-butyl methyl ether (t-BuME), and tert-butyl methyl ketone (t-BuMK) was studied in water (D2O) using high-resolution nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering. Phase separation was thermodynamically modeled as a two-state process which resulted in a simple curve which can be used for fitting of NMR data and obtaining all important thermodynamic parameters using simple formulas presented in this paper. The model is based on a modified van't Hoff equation. Phase separation temperatures T p and thermodynamic parameters (enthalpy and entropy change) connected with the phase separation of PNIPAM were obtained using this method. It was determined that T p is dependent on additives in the following order: T p(t-BuAM) > T p(t-BuOH) > T p(t-BuME) > T p(t-BuMK). Also, either increasing the additive concentration or increasing pK a of the additive leads to depression of T p. Time-resolved 1H NMR spin-spin relaxation experiments (T 2) performed above the phase separation temperature of PNIPAM revealed high colloidal stability of the phase-separated polymer induced by the additives (relative to the neat PNIPAM/D2O system). Small quantities of selected suitable additives can be used to optimize the properties of PNIPAM preparations including their phase separation temperatures, colloidal stabilities, and morphologies, thus improving the prospects for the application.
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Affiliation(s)
- Nadiia Velychkivska
- Department
of NMR Spectroscopy, Institute of Macromolecular
Chemistry AS CR, v.v.i., Heyrovsky Sq. 2, Prague 6 162 06, Czech Republic
| | - Larisa Starovoytova
- Department
of NMR Spectroscopy, Institute of Macromolecular
Chemistry AS CR, v.v.i., Heyrovsky Sq. 2, Prague 6 162 06, Czech Republic
| | - Václav Březina
- Faculty
of Mathematics and Physics, Department of Macromolecular Physics, Charles University, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
| | - Lenka Hanyková
- Faculty
of Mathematics and Physics, Department of Macromolecular Physics, Charles University, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
| | - Jonathan P. Hill
- National
Institute for Materials Science (NIMS), International Center for Materials
Nanoarchitectonics (WPI-MANA), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Jan Labuta
- National
Institute for Materials Science (NIMS), International Center for Materials
Nanoarchitectonics (WPI-MANA), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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7
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Zhang Y, Tang H, Wu P. Insights into the thermal phase transition behavior of a gemini dicationic polyelectrolyte in aqueous solution. SOFT MATTER 2018; 14:4380-4387. [PMID: 29767208 DOI: 10.1039/c8sm00598b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The thermal-induced phase transition behavior of a LCST-type poly(ionic liquid) (PIL) aqueous solution with gemini-cationic structure, poly[(1,8-octanediyl-bis(tri-n-butylphosphonium)4-styrene sulfonate)] (P[SS-P2]), was investigated in this paper. Based on the calorimetric measurements, a unique dependence of transition points on concentration was found in P[SS-P2] aqueous solution compared to its mono-cationic PIL and [SS-P2] aqueous solution. Optical microscopy showed that globular microscopic droplets were formed during the phase transition, suggesting that gemini dications and the possible dynamic ionic bonds may facilitate the liquid-liquid phase separation (LLPS) in P[SS-P2] aqueous solution. Temperature-variable 1H NMR and FT-IR investigations manifested that the dehydration of anionic chains instead of the dehydration of dications served as the driving force of the phase separation in the P[SS-P2] aqueous solution, implying that the polymerized anions tended to aggregate together first and lay in the core with dications distributed around the globules at the end of the transition process. Notably, considering that the SO3 groups in the gemini-cationic system tended to be distributed around the surface of collapsed anionic main chains rather than be wrapped into the aggregates, it is supposed that dynamic ionic bonding between dication and anionic backbones was distributed in the periphery of the globules and acted as the "cross-linkers", which enhanced the stability of regular droplets after the phase transition in P[SS-P2] aqueous solution.
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Affiliation(s)
- Yingna Zhang
- The State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science and Laboratory for Advanced Materials, Fudan University, Shanghai 200433, China.
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8
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Chakraborty I, Mukherjee K, De P, Bhattacharyya R. Monitoring Coil–Globule Transitions of Thermoresponsive Polymers by Using NMR Solvent Relaxation. J Phys Chem B 2018; 122:6094-6100. [DOI: 10.1021/acs.jpcb.8b02179] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Konefał R, Spěváček J, Černoch P. Thermoresponsive poly(2-oxazoline) homopolymers and copolymers in aqueous solutions studied by NMR spectroscopy and dynamic light scattering. Eur Polym J 2018. [DOI: 10.1016/j.eurpolymj.2018.01.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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10
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Zhang Y, Tang H, Wu P. Multiple interaction regulated phase transition behavior of thermo-responsive copolymers containing cationic poly(ionic liquid)s. Phys Chem Chem Phys 2017; 19:30804-30813. [DOI: 10.1039/c7cp05846b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Schematic illustration of the phase transition mechanism of the P(OEGMA-co-BVIm[SCN]) copolymer.
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Affiliation(s)
- Yingna Zhang
- The State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science and Laboratory for Advanced Materials
- Fudan University
- Shanghai 200433
- China
| | - Hui Tang
- The State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science and Laboratory for Advanced Materials
- Fudan University
- Shanghai 200433
- China
| | - Peiyi Wu
- The State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science and Laboratory for Advanced Materials
- Fudan University
- Shanghai 200433
- China
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11
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Filippov SK, Bogomolova A, Kaberov L, Velychkivska N, Starovoytova L, Cernochova Z, Rogers SE, Lau WM, Khutoryanskiy VV, Cook MT. Internal Nanoparticle Structure of Temperature-Responsive Self-Assembled PNIPAM-b-PEG-b-PNIPAM Triblock Copolymers in Aqueous Solutions: NMR, SANS, and Light Scattering Studies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:5314-5323. [PMID: 27159129 DOI: 10.1021/acs.langmuir.6b00284] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this study, we report detailed information on the internal structure of PNIPAM-b-PEG-b-PNIPAM nanoparticles formed from self-assembly in aqueous solutions upon increase in temperature. NMR spectroscopy, light scattering, and small-angle neutron scattering (SANS) were used to monitor different stages of nanoparticle formation as a function of temperature, providing insight into the fundamental processes involved. The presence of PEG in a copolymer structure significantly affects the formation of nanoparticles, making their transition to occur over a broader temperature range. The crucial parameter that controls the transition is the ratio of PEG/PNIPAM. For pure PNIPAM, the transition is sharp; the higher the PEG/PNIPAM ratio results in a broader transition. This behavior is explained by different mechanisms of PNIPAM block incorporation during nanoparticle formation at different PEG/PNIPAM ratios. Contrast variation experiments using SANS show that the structure of nanoparticles above cloud point temperatures for PNIPAM-b-PEG-b-PNIPAM copolymers is drastically different from the structure of PNIPAM mesoglobules. In contrast with pure PNIPAM mesoglobules, where solidlike particles and chain network with a mesh size of 1-3 nm are present, nanoparticles formed from PNIPAM-b-PEG-b-PNIPAM copolymers have nonuniform structure with "frozen" areas interconnected by single chains in Gaussian conformation. SANS data with deuterated "invisible" PEG blocks imply that PEG is uniformly distributed inside of a nanoparticle. It is kinetically flexible PEG blocks which affect the nanoparticle formation by prevention of PNIPAM microphase separation.
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Affiliation(s)
- Sergey K Filippov
- Institute of Macromolecular Chemistry , AS CR, Heyrovsky Sq. 2, Prague, Prague 6, 162 06, Czech Republic
| | - Anna Bogomolova
- Institute of Macromolecular Chemistry , AS CR, Heyrovsky Sq. 2, Prague, Prague 6, 162 06, Czech Republic
| | - Leonid Kaberov
- Institute of Macromolecular Chemistry , AS CR, Heyrovsky Sq. 2, Prague, Prague 6, 162 06, Czech Republic
| | - Nadiia Velychkivska
- Institute of Macromolecular Chemistry , AS CR, Heyrovsky Sq. 2, Prague, Prague 6, 162 06, Czech Republic
| | - Larisa Starovoytova
- Institute of Macromolecular Chemistry , AS CR, Heyrovsky Sq. 2, Prague, Prague 6, 162 06, Czech Republic
| | - Zulfiya Cernochova
- Institute of Macromolecular Chemistry , AS CR, Heyrovsky Sq. 2, Prague, Prague 6, 162 06, Czech Republic
| | - Sarah E Rogers
- ISIS-STFC, Rutherford Appleton Laboratory, Chilton, OX11 0QX Oxon United Kingdom
| | - Wing Man Lau
- School of Pharmacy, University of Reading, Whiteknights , PO Box 224, Reading, RG6 6AD Berkshire, United Kingdom
| | - Vitaliy V Khutoryanskiy
- School of Pharmacy, University of Reading, Whiteknights , PO Box 224, Reading, RG6 6AD Berkshire, United Kingdom
| | - Michael T Cook
- Department of Pharmacy & Research Centre in Topical Drug Delivery and Toxicology, University of Hertfordshire , Hatfield, AL10 9AB Hertfordshire, United Kingdom
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Radecki M, Spěváček J, Zhigunov A, Sedláková Z, Hanyková L. Temperature-induced phase transition in hydrogels of interpenetrating networks of poly(N-isopropylacrylamide) and polyacrylamide. Eur Polym J 2015. [DOI: 10.1016/j.eurpolymj.2015.04.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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He J, Tremblay L, Lacelle S, Zhao Y. How can photoisomerization of azobenzene induce a large cloud point temperature shift of PNIPAM? Polym Chem 2014. [DOI: 10.1039/c4py00546e] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a comprehensive study of the photo-induced phase transition of azobenzene-containing poly(N-isopropylacrylamide) (PNIPAM) in block copolymers (BCPs) upon the isomerization of azobenzene in the mixed solvent of water and dioxane.
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Affiliation(s)
- Jie He
- Département de chimie
- Université de Sherbrooke
- Sherbrooke, Canada J1K 2R1
- Department of Chemistry
- University of Connecticut
| | - Luc Tremblay
- Département de médecine nucléaire et de radiobiologie and Centre d'imagerie moléculaire de Sherbrooke
- Université de Sherbrooke
- Sherbrooke, Canada J1K 2R1
| | - Serge Lacelle
- Département de chimie
- Université de Sherbrooke
- Sherbrooke, Canada J1K 2R1
| | - Yue Zhao
- Département de chimie
- Université de Sherbrooke
- Sherbrooke, Canada J1K 2R1
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14
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Rheology and phase behavior of thermo-reversible pentablock terpolymer hydrogel. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/polb.23343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Temperature-induced phase transition in hydrogels of interpenetrating networks poly(N-isopropylmethacrylamide)/poly(N-isopropylacrylamide). Colloid Polym Sci 2013. [DOI: 10.1007/s00396-013-2992-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Hanykova L, Radecki M. NMR and Thermodynamic Study of Phase Transition in Aqueous Solutions of Thermoresponsive Amphiphilic Polymer. CHEM LETT 2012. [DOI: 10.1246/cl.2012.1044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Lenka Hanykova
- Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University
| | - Marek Radecki
- Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University
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17
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1H NMR study of temperature-induced phase transitions in aqueous solutions of poly(N-isopropylmethacrylamide)/poly(N-vinylcaprolactam) mixtures. Polym Bull (Berl) 2012. [DOI: 10.1007/s00289-012-0831-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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18
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NMR and DSC study of temperature-induced phase transition in aqueous solutions of poly(N-isopropylmethacrylamide-co-acrylamide) copolymers. Colloid Polym Sci 2012. [DOI: 10.1007/s00396-012-2701-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Spěváček J. NMR Investigations of Temperature-Induced Phase Transition in Aqueous Polymer Solutions. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.201000107] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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