Amphiphilic block copolymers (BCPs) form self-assembled aggregates in solution with a range of morphologies including spherical micelles, cylindrical micelles, vesicles (polymersomes) and bicontinuous nanospheres. This research focuses on the formation of bicontinuous nanospheres using a number of different BCPs for use in thermo-responsive drug delivery. It has been shown previously that PEO-b-PODMA (poly(ethylene oxide)-block-poly(octadecyl methacrylate)) forms semi-crystalline bicontinuous nanospheres with a phase transition temperature (Tm) of 21.8°C. 1 This corresponds to the melting transition of the semi-crystalline PODMA block. To increase the Tm, while maintaining all other properties, the hydrophobic monomer ODMA, was replaced with docosyl methacrylate (DOMA), which has a higher melting point. Upon self-assembly the PEO-b-PDOMA (25 wt% PEO) formed bicontinuous nanospheres. Analysis using differential scanning calorimetry (DSC) revealed the Tm of PEO-b-PDOMA in bulk and aggregate solution to be 41.3ºC and 41.1ºC respectively. To further demonstrate the control achieved over the Tm, random copolymers of ODMA and DOMA using a PEO macroinitiator were synthesised at varying wt% ratios of PODMA:PDOMA. DSC analysis of these polymers showed that an increase in PDOMA led to an increase in the Tm for the bulk and self-assembled samples. The controlled release of Ibuprofen from these bicontinuous nanospheres is being investigated to determine the rate of release and the optimum temperature for release, following a previously used method2. The concentration of release will then be analysed using HPLC. To incorporate acid functionality into the bicontinuous nanospheres PMAA-b-PODMA (poly(methacrylic acid)-block-poly(octadecyl methacrylate)) were synthesised (via ATRP) with hydrophilic wt% of 15-25%. The self-assembled solution of PMAA-b-PODMA at 20 wt% PMAA was analysed using DLS and TEM, which indicates the presence of bicontinuous nanospheres. 1. McKenzie, B. E.; Nudelman, F.; Bomans, P. H. H.; Holder, S. J.; Sommerdijk, N., Temperature-Responsive Nanospheres with Bicontinuous Internal Structures from a Semicrystalline Amphiphilic Block Copolymer. Journal of the American Chemical Society 2010, 132 (30), 10256-10259. 2. Holder, S. J.; Woodward, G.; McKenzie, B.; Sommerdijk, N. A. J. M., Semi-crystalline block copolymer bicontinuous nanospheres for thermoresponsive controlled release. RSC Advances 2014, 4 (50), 26354-26358.

Controlling the self-assembly of semicrystalline block copolymers toward manipulating the phase transition of bicontinuous nanospheres

249th National Meeting (2015)

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