HIGHLY BRANCHED POLY(N-ISOPROPYL ACRYLAMIDE) BEHAVIOUR AND RESPONSE TO BACTERIA

摘要

Highly branched poly(N-isopropyl acrylamide) has been synthesized by us with various end groups using self-condensing RAFT polymerization. The end groups of these polymers can be modified to provide initially carboxlic acid groups then these groups are amidated with amine functional antibiotics or the binding fragments of antibiotics. These end groups have then been shown to bind to bacteria and perturbation of the solvation of the end groups on binding decreases the coil-to-globule transition. This decrease in the T_(c-g) at constant temperature can drive the system through the transition on binding. Thus binding of the polymer provides a signal of the presence of bacteria. Our work has now also shown, using a combination of DSC, FTIR, use of fluorescence probes and cloud point measurements, that for high degrees of branching the polymers in solution exist as core-shell particles. That is at certain temperatures they have globular desolvated cores with chain extended solvated shells. The swelling of shells, we propose, is caused by local penetration of the charged end-groups into the outer segments of the polymer coil. We thank the MOD, EPSRC, Wellcome Trust, TSB and Smith and Nephew for funding.