solution properties of water-soluble “smart” poly(n-acryloyl-n′-ethyl piperazine-co-methyl methacrylate)解决方案性能的水溶性u201c智能u201d聚n-acryloyl-nu2032乙piperazine-co-methyl丙烯酸甲酯).pdf

Polymers 2012, 4, 32-45; doi:10.3390/polym4010032 OPEN ACCESS polymers ISSN 2073-4360 /journal/polymers Article Solution Properties of Water-Soluble “Smart” Poly(N-acryloyl-N ′-ethyl piperazine-co-methyl methacrylate) G. Roshan Deen Soft Materials Laboratory, Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1-Nanyang Walk, 637616, Singapore; E-Mail: Roshan.gulam@.sg; Tel.: +65-6790-3826; Fax: +65-6896-9414 Received: 28 November 2011; in revised form: 21 December 2011 / Accepted: 5 January 2012 / Published: 5 January 2012 Abstract: Water-soluble copolymers of N-acryloyl-N ′-ethylpiperazine (AcrNEP) with methyl methacrylate (MMA) were synthesized to high conversion by free-radical solution polymerization. The composition of the copolymers was determined using Fourier Transform Infra-red Spectroscopy (FTIR). Copolymers containing AcrNEP content above 44 mol% were readily soluble in water and exhibited the critical solution temperature behavior. The copolymers were strongly responsive to changes in pH of the external medium due to the presence of tertiary amine functions that could be protonated at low pH. The influence of various factors such as copolymer composition, pH, temperature, salt and surfactant concentration on the LCST of the copolymers were systematically studied. The intrinsic viscosity of the copolymers in dimethyl formamide decreased with increase in temperature due to a decre