Thermoresponsive Polymers: Synthesis and Properties
Natun
Dasgupta
PhD
Student,
Department
of
Chemistry
University
of
Waterloo
Friday,
February
28,
2019
11:30
a.m.
E6-4022
Abstract
The synthesis of thermoresponsive polymers is of interest for various applications. The combination of polysaccharides with thermoresponsive polymers, in particular, leads to unique properties with high biocompatibility and biodegradability. These materials have been used, among others, in biomedical applications such as in gene delivery and tissue engineering. “Living” radical polymerization methods known as Reversible-Deactivation Radical Polymerization (RDRP) techniques were mainly employed to synthesize such polymers. Different variations of the RDRP techniques for the production of controlled architecture polymers will be overviewed.
We are mainly interested in the applications of thermoresponsive polysaccharides, in the form of starch nanoparticles (SNPs), for the extraction of oil from tar sands and for the settling of tar sand tailings. These were obtained by the modification of starch with thermoresponsive poly(di(ethylene glycol) methyl ether methacrylate) (PMEO2MA) segments through RAFT (Reversible Addition-Fragmentation chain Transfer) grafting. Since PMEOM2A exhibits an LCST (Lower Critical Solution Temperature), the polymer-grafted SNPs are amphiphilic above the LCST of the thermoresponsive polymer and hydrophilic below the LCST. The synthetic methods used provide easy control over the characteristics of the grafted SNPs (number and length of grafted PMEO2MA segments), and therefore over their hydrophilic-lipophilic balance (HLB). Characterization of the SNP-g-PMEO2MA samples involved 1H NMR, UV-visible spectroscopy, TEM and DLS analysis, and the grafted PMEO2MA chains were cleaved from the starch substrates for analysis by gel permeation chromatography.