The diblock copolymer, CH3O-(CH2CH2O)113-(COCH2CH2CH2CH2CH2O)99-H was prepared by the tin-catalyzed, ring-opening polymerization of e-caprolactone from the alcohol terminus of poly(ethelene glycol) monomethyl ether, Mn ~ 5,000. Polymer micelles were made by dispersing the diblock in ultrapure water by solvent evaporation of THF. The critical micelle concentration was 1.44 mg/L and increased with increasing temperature. DSC showed that the polycaprolactone core was semi-crystalline with a melting point between 40 and 55 �C. Dibucaine was trapped in the core with a loading of 16% and an encapsulation efficiency of 28%. The rate of thermally triggered release of the dibucaine was determined isothermally at 37 �C, a temperature below the melting point of the polycaprolcatone core and at 57 �C, above the melting point, and pulse between 37 �C and 57 �C, to mimic heating that would be performed in the body. The release rate at 57 �C was higher and 90% of the dibucaine was released after 4 hours.

Dibucaine encapsulation in polymer micelles having a semi-crystalline core made from a poly(ethylene-b-caprolactone) diblock copolymer

245th National Meeting (2013)

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