scholarly journals Cyclodextrin-induced host–guest effects of classically prepared poly(NIPAM) bearing azo-dye end groups

2012 ◽  
Vol 8 ◽  
pp. 1929-1935 ◽  
Author(s):  
Gero Maatz ◽  
Arkadius Maciollek ◽  
Helmut Ritter
Keyword(s):  
Acid Chloride ◽  
Lower Critical Solution Temperature ◽  
Azo Dye ◽  
Chain Transfer ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
End Groups ◽  
Hyperbranched Polyglycerol ◽  
A Chain ◽  
End Group

A thermo-, pH- and cyclodextrin- (CD) responsive poly(N-isopropylacrylamide) (PNIPAM), with a N,N-dimethylaminoazobenzene end group was synthesized. Using 3-mercaptopropionic acid as a chain transfer agent, PNIPAM with a well-defined COOH end group was obtained. The acid end group was transferred to the corresponding acid chloride and then functionalized with N,N-dimethyl[4-(4’-aminophenylazo)phenyl]amine. This dye-end-group-labeled polymer showed acidochromic effects, depending on the pH and the presence of randomly methylated β-cyclodextrin (RAMEB-CD). Also higher cloud-point values for the lower critical solution temperature (LCST) in the presence of RAMEB-CD were observed. Additionally, this azo-dye-end-group-labeled polymer was complexed with hyperbranched polyglycerol (HPG) decorated with β-CD to generate hedgehog-like superstructures.

Hyperbranched Polymers via RAFT Copolymerization of an Acryloyl Trithiocarbonate

2007 ◽  
Vol 60 (6) ◽  
pp. 396 ◽  
Author(s):  
Andrew P. Vogt ◽  
Sudershan R. Gondi ◽  
Brent S. Sumerlin
Keyword(s):  
Click Chemistry ◽  
Lower Critical Solution Temperature ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Chain Transfer Agent ◽  
Solution Temperature ◽  
Dipolar Cycloaddition ◽  
Critical Solution Temperature ◽  
Reversible Addition ◽  
End Groups

Hyperbranched copolymers of N-isopropylacrylamide (NIPAM) and styrene were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of a novel acryloyl trithiocarbonate, namely 1-[3-(2-methyl-2-dodecylsulfanylthiocarbonylsulfanylpropionyloxy)propyl]-1H-[1,2,3]triazol-4-ylmethyl acrylate. By employing an example of ‘click chemistry’, we were able to prepare the vinyl RAFT chain transfer agent (CTA) by copper-catalyzed 1,3-dipolar cycloaddition of an azido-functionalized trithiocarbonate and propargyl acrylate. The resulting CTA facilitated the preparation of highly branched poly(N-isopropylacrylamide) (PNIPAM) and polystyrene. Interestingly, the branched PNIPAM demonstrated a reduced lower critical solution temperature (LCST) of 25°C as opposed to the conventional value of 32°C expected for linear PNIPAM, an effect attributed to increased contribution of hydrophobic dodecyl trithiocarbonate end groups.

A polyelectrolyte-containing copolymer with a gas-switchable lower critical solution temperature-type phase transition

2019 ◽  
Vol 10 (2) ◽  
pp. 260-266 ◽  
Author(s):  
Jin-Jin Li ◽  
Yin-Ning Zhou ◽  
Zheng-Hong Luo ◽  
Shiping Zhu
Keyword(s):  
Phase Transition ◽  
Cloud Point ◽  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Type Phase

A polyelectrolyte-containing copolymer with a CO2/N2-switchable cloud point, resulting from the gas-induced alternation of hydrophilicity, was prepared.

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