Molecular Sequence Control Over Thermo-Triggered Micellization And Smart Nanogels Of Copolymers Based On Aldehyde-Functionalized Monomer

Convenient and well-controlled synthesis of smart nanogels has been extensively studied for the applications in the nanomaterials field. By adjusting the sequence of amino acids in polypeptides can effectively control the chain interaction, chain folding modes, and control their assembly into proteins with different structures and living functions. Thus regulating the sequences of a copolymer may lead to the variation of assembly processes and structure adjustability in the process of self-assembly. This thesis describes the sequence control over thermo-triggered micellization and nanogels of copolymers of poly[poly(ethylene glycol) methyl ether methacrylate] (PEGMA) and 1,3-(4-formylphenoxy)-2-hydroxypropyl methacrylate (FPHPMA). To this end, the well-defined copolymers in the sequences of P(FPHPMA-ran-PEGMA), P(FPHPMA-ran-PEGMA)-b-PFPHPMA and P(FPHPMA-ran-PEGMA)-b-PPEGMA, at unit ratio of [FPHPMA]:[PEGMA]≈1:1 and a fixed overall degree of polymerization or DP≈50, were synthesized via reversible addition-fragmentation chain transfer radical polymerization or RAFT polymerization under mild visible light radiation at 25℃. The results demonstrated that altering the sequence from P(FPHPMA-ran-PEGMA) to P(FPHPMA-ran-PEGMA)-b-PPEGMA or P(FPHPMA-ran-PEGMA)-b-PFPHPMA led to the increase of cloud point and decrease of hydrodynamic diameter from hundreds nm to tens nm. Moreover, altering the copolymer sequence resulted in the thermo-triggered micellization changing from the insertion/expulsion mechanism of single chains to fusion/fission mechanism of their pre-assembled "polymerases". The hysteresis effect and solvent isotopic effect varied with the sequence of copolymers. Moreover, the thermally induced dehydration and apparent reactivity of aldehyde functionalities of swollen micelles also varied with the copolymer sequence. These thermally induced micelles could react with diamine to form nanogels. The pH- and/or thermo-triggered swellability of these nanogels depended on the copolymer sequence.