Stimuli responsive (i.e. Lower / Upper Critical Solution Temperature) polymer materials have been shown to be effective trigger systems. However in order to be incorporated into devices polymers must be tuned to exactly match desired stimulating events. Part of the arsenal used to develop these systems are changing polymer architecture. Branched polymers offer different solution, rheological and surface properties to their linear analogues. Highly branched materials, prepared via dual self-condensing vinyl (SCV) and reversible addition-fragmentation transfer (RAFT) polymerisation, have unique properties such as their single-molecule core-shell structures. These materials exhibit core-shell properties due to their dendritic branching architectures. Consisting of a collapsed inner core and a swollen, solvated outer core. It has been shown that converting chain ends to binding ligands can trigger a collapse event across the polymer outer shell and desolvate the entire molecule. Previous demonstrated applications have included rheology modifiers, cell lifting systems and pathogen (bacterium) sensors. The strength of the desolvation has been shown to lift bacteria out of a biofilm and incorporation of drug molecules into chain ends can reduce their cytotoxicity to the host whilst improving their efficacy against pathogens. All these functions come from the unique core-shell structure exhibited by the branched polymer architecture. We have investigated varying the degree of branching to change polymer properties as shown in F1. Control over branching density can alter the polymer globule, shifting the LCST temperature to higher and lower extremes. Conversely affecting the charge on the chain end can fundamentally affect the degree of desolvated collapse without greatly affecting the transition temperature. Control over polymer architecture, and these fundamental properties, are an important aspect of their use in next generation materials.

Preparing core-shell single molecules: Architecturally sound highly branched polymers with tuneable properties

253rd National Meeting (2017)

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