Thermoresponsive polymers are used in wide range of applications in nanotechnology and biotechnology. These polymers exhibit temperature-dependent and reversible volume phase transition. Polymers having a lower critical solution temperature (LCST) become insoluble upon heating, while those having upper critical solution temperature (UCST) become soluble upon heating. Poly(N-isopropylacrylamide) (PNIPAM) is the most studied thermoresponsive polymers, particularly for biomedical applications because it exhibits an LCST at 32 oC in water and the LCST of PNIPAM is relatively insensitive to environmental factors. However, applications are limited due to its non-biodegradability. Herein, we report the synthesis of thermoresponsive polycaprolactones (PCLs) having LCST close to physiological temperature with the added advantage of biocompatibility and biodegradability. Homopolymers of di-, tri-, and tetra-oligoethyelene-substituted caprolactones - poly(γ-2-(2-methoxyethoxy)ethoxy-ε-caprolactone) [PMEECL], poly(γ-2(2-(2-methoxyethoxy)ethoxy)ethoxy-ε-caprolactone) [PMEEECL], and poly(γ-2(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)ethoxy-ε-caprolactone) [PMEEEECL] - of varying molecular weight were synthesized and characterized. Sharp transitions were observed with LCSTs ranging from 37 to 80 oC. Block copolymers of hydrophobic γ-benzyl polycaprolactone and hydrophilic PMEEEECL with varying ratios of each block gave LCSTs between 40 and 50 oC.

Tuning the lower critical solution temperature of oligoethylene substituted polycaprolactones

2019 Fall National Meeting

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