Polymerisation-Induced Self-Assembly (PISA): a powerful platform technology for bespoke polymer particles Prof. Steve Armes Department of Chemistry, University of Sheffield, UK Polymerisation-induced self-assembly (PISA) is a powerful and versatile technique for the rational synthesis of concentrated dispersions of block copolymer nano-objects of controllable size, shape and surface chemistry. In essence, an insoluble block is grown from one end of a soluble block in a suitable solvent. Once the growing block reaches a certain critical degree of polymerisation, micellar nucleation occurs and the soluble block then acts as a steric stabiliser. Unreacted monomer diffuses into the copolymer cores, which leads to a relatively high local concentration and hence a significant rate acceleration. Depending on the target diblock copolymer composition, the final copolymer morphology can be spheres, worms or vesicles. The design rules for PISA are generic: such syntheses may be conducted in water, polar solvents or non-polar solvents using reversible addition-fragmentation chain transfer (RAFT) polymerisation. Over the past decade, PISA has become established as a highly versatile platform technology for the rational design of bespoke polymer colloids. For example, such block copolymer nano-objects can be used as highly biocompatible worm gels for cell biology studies, as dispersants for organic agrochemical actives, as next- generation lubricant additives for ultralow viscosity automotive engine oils, or for the design of uniquely thermoresponsive amphiphilic diblock copolymers that form spheres, worms or vesicles in aqueous solution simply by adjusting the temperature from 5°C to 50°C. Various examples of PISA formulations will be discussed in this lecture.
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