scholarly journals Comparison of Thermoresponsive Hydrogels Synthesized by Conventional Free Radical and RAFT Polymerization

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2697 ◽  
Author(s):  
Fanny Joubert ◽  
Peyton Cheong Phey Denn ◽  
Yujie Guo ◽  
George Pasparakis
Keyword(s):  
Free Radical ◽  
Room Temperature ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Hydrolytic Stability ◽  
Monomer Concentration ◽  
Crosslinking Density ◽  
Dye Release ◽  
Reversible Addition ◽  
Thermoresponsive Hydrogels

We compared the influence of the polymerization mechanism onto the physical characteristics of thermoresponsive hydrogels. The Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels were successfully synthesized using reversible addition-fragmentation chain-transfer (RAFT) and free radical polymerization (FRP). The gels were prepared while using different crosslinker feed and monomer concentration. The swelling, dye release, and hydrolytic stability of the gels were investigated in water, or in representative komostrope and chaotrope salt solutions at room temperature and at 37 °C. It was found that the swelling ratio (SR) of the RAFT gels was significantly higher than that of the FRP gels; however, an increased crosslinking density resulted in a decrease of the SR of the RAFT gels as compared to the corresponding gels that are made by FRP, which indicates the limitation of the cross-linking efficiency that is attained in RAFT polymerization. Additionally, an increased monomer concentration decreased the SR of the RAFT gels, whereas a similar SR was observed for the FRP gels. However, the SR of both RAFT and FRP gels in NaSCN and Na2SO4 solutions were similar. Finally, the rate of dye release was significantly slower from the RAFT gels than the FRP gels and the hydrolytic stability of the RAFT gels was lower than that of FRP gels in water, but maintained similar stability in Na2SO4 and NaSCN solutions.

Enzyme catalysis-induced RAFT polymerization in water for the preparation of epoxy-functionalized triblock copolymer vesicles

2018 ◽  
Vol 9 (39) ◽  
pp. 4908-4916 ◽  
Author(s):  
Qin Xu ◽  
Yuxuan Zhang ◽  
Xueliang Li ◽  
Jun He ◽  
Jianbo Tan ◽  
...  
Keyword(s):  
Enzyme Catalysis ◽  
Triblock Copolymer ◽  
Room Temperature ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Reversible Addition

Enzyme catalysis-induced aqueous reversible addition–fragmentation chain transfer (RAFT) polymerization was conducted at room temperature for the preparation of epoxy-functionalized triblock copolymer vesicles.

Room temperature synthesis of block copolymer nano-objects with different morphologies via ultrasound initiated RAFT polymerization-induced self-assembly (sono-RAFT-PISA)

2020 ◽  
Vol 11 (21) ◽  
pp. 3564-3572
Author(s):  
Jing Wan ◽  
Bo Fan ◽  
Yiyi Liu ◽  
Tina Hsia ◽  
Kaiyuan Qin ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Self Assembly ◽  
Room Temperature ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Aqueous System ◽  
Temperature Synthesis ◽  
Room Temperature Synthesis ◽  
System P ◽  
Reversible Addition

The first room temperature synthesis of diblock copolymer nano-objects with different morphologies using ultrasound (990 kHz) initiated reversible addition-fragmentation chain transfer PISA (sono-RAFT-PISA) in aqueous system.

UV light-initiated RAFT polymerization induced self-assembly

2015 ◽  
Vol 6 (34) ◽  
pp. 6129-6132 ◽  
Author(s):  
Zhenzhong Liu ◽  
Gongjun Zhang ◽  
Wei Lu ◽  
Youju Huang ◽  
Jiawei Zhang ◽  
...  
Keyword(s):  
Self Assembly ◽  
Room Temperature ◽  
Chain Transfer ◽  
Uv Light ◽  
Raft Polymerization ◽  
Reversible Addition ◽  
New Strategy

Reversible addition–fragmentation chain transfer (RAFT) polymerization induced self-assembly (PISA) initiated by UV light is exploited as a new strategy to prepare polymeric nanomicelles at room temperature.

Synthesis and characterization of poly(vinyl chloride-graft-2-vinylpyridine) graft copolymers using a novel macroinitiator by reversible addition-fragmentation chain transfer polymerization

e-Polymers ◽  
2014 ◽  
Vol 14 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Temel Öztürk ◽  
Melahat Göktaş ◽  
Bedrettin Savaş ◽  
Mustafa Işıklar ◽  
Mehmet Nuri Atalar ◽  
...  
Keyword(s):  
Vinyl Chloride ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Graft Copolymers ◽  
Monomer Concentration ◽  
Polymerization Reaction ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Poly Vinyl Chloride ◽  
Reversible Addition

AbstractSynthesis of poly(vinyl chloride-graft-2-vinylpyridine) graft copolymers was carried out by reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-vinylpyridine using a novel macroinitiator (RAFT macroinitiator). For this purpose, RAFT macroinitiator was obtained from the potassium salt of ethyl xanthogenate and poly(vinyl chloride) (PVC). Then the graft copolymers were synthesized by using RAFT macroinitiator and 2-vinylpyridine. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the polymerization reaction were studied. The effect of the reaction conditions on the heterogeneity index and molecular weight was also investigated. The block lengths of the graft copolymers were calculated by using 1H nuclear magnetic resonance (1H NMR) spectra. The block lengths of the copolymers could be adjusted by varying the monomer and initiator concentrations. The characterizations of the samples were carried out by using 1H NMR, Fourier-transform infrared spectroscopy, gel-permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and fractional precipitation (γ value) techniques. RAFT polymerization is used to control the polymerization of 2-vinylpyridine over a broad range of molecular weights.

A New Method in Improving RAFT Polymerization Rate of Styrene

2012 ◽  
Vol 482-484 ◽  
pp. 1886-1889
Author(s):  
Qing Bo Yu ◽  
Xian Hua Li
Keyword(s):  
Free Radical ◽  
Radical Polymerization ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Free Radical Polymerization ◽  
Polymerization Rate ◽  
New Method ◽  
Continuous Polymerization ◽  
Reversible Addition ◽  
Living Free Radical Polymerization

A batch reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene was investigated. The results show that the process has good characteristics of living free radical polymerization. The polymerization rate is higher comparing continuous polymerization.

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