Abstract. The homopolymerization of phenyl acrylate (PA) was investigated for the first time by nitroxide mediated polymerization (NMP) with the succinimidyl form of the SG1-based unimolecular initiator 2-[N-tert-butyl-2,2-(dimethylpropyl)-aminooxy]propionic acid (BlocBuilder MA). The control of PPA homopolymerization was improved by the use of 15 mol% additional free nitroxide SG1 ([tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino]oxidanyl) and dispersities, M w /M n , of around 1.2 were achieved. A PPA homopolymer was then successfully chain-extended with diethyl acrylamide (DEAAm) to form a block copolymer of PPA-b-PDEAAm where the PDEAAm segment is thermo-responsive, while the PPA block is potentially UV-active. The thermo-responsive behavior of the block copolymer in 0.5 wt% aqueous solution was studied by UV-Vis spectrometry and dynamic light scattering (DLS), indicating cloud point temperatures of 26-30°C, close to that reported for PDEAAm homopolymers.
The synthesis and characterization of a novel copolymer Poly(acryl amide-co-acrylamido azobenzene) (P(AAm-co-AAAB)) and its hydrohydrogels consisting of acrylamide (AAm), acrylamido-azobenzene (AAAB) with a photo-responsive azobenzene chromophore, were reported in this article. The copolymerization was carried out with a free-radical polymerization route using 2,2-azobisisobutyronitrile (AIBN) as an initiator, tetrahydrofuran (THF) as a solvent and N,N-methylene bisacrylamide (MBAA) as a crosslinking agent for hydrogel. The structures of P(AAm-co-AAAB) were charactered by Fourier transform infrared spectroscopy (FT-IR) and 1 H-NMR spectroscopy, and their photo-responsive behaviors was studied. The spectra of P(AAm-co-AAAB) copolymer solution irradiated with UV light showed one strong intensity peak at about 342 nm, and with the irradiation time increased, the intensity of the absorption decreased. The hydrogels also showed good photoresponses. With the UV irradiation time increased, the volume of the hydrogels decreased gradually. The photoresponsive behaviors was reversible, without the irradiation, the volume of the hydrohydrogels increased to the original state. This photoresponsive behavior was caused by the cis-trans isomerism of azobenzide in the chains of their structures.
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