In an effort to develop stimuli-responsive polymer-based drug delivery vehicles, functionalized poly(caprolactone)s (PCL) are investigated. This report presents the synthesis of new functionalized e-caprolactone monomers and diblock copolymers as well as the preparation of thermosensitive micelles for drug delivery applications. A multi-step synthetic procedure yielded two functionalized caprolactone monomers, ?-(2-methoxyethoxy)-?-caprolactone (MECL) and ?-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-?-caprolactone (MEEECL). Diblock copolymers (PMEEECL-b-PMECL) from the two monomers were prepared by ring-opening polymerization (ROP) using stannous 2-ethylhexanoate as catalyst and benzyl alcohol as the initiator. Various MEEECL:MECL monomer ratios were employed to achieve varying block lengths, which were correlated with properties like critical micelle concentration (CMC) and lower critical solution temperature (LCST). The hydrophilic block, PMEEECL, contributes to the thermosensitive nature of the polymer, due to the balance of its hydrophobic caprolactone backbone and hydrophilic MEEE side chain. The block lengths were shown to affect the LCST, which was lowered from 43 �C to 31 �C upon increased incorporation of MECL relative to MEEECL, shown in the figure below. The polymers demonstrated self-assembly into spherical micelles as evidenced by pyrene fluorescence CMC studies, dynamic light scattering, and transmission electron microscopy. Further study of the cytotoxicity and drug loading efficiencies of the polymers will be conducted. This preliminary work suggests the opportunity for polymeric micelles with highly tunable thermoresponsive behavior.

Towards smart polymeric drug carriers: Self-assembling ?-substituted polycaprolactones with highly tunable thermoresponsive behavior

247th National Meeting (2014)

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