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Controlling the Functionality of Block Copolymer Bicontinuous Nanospheres

Monaghan, Olivia Rose (2015) Controlling the Functionality of Block Copolymer Bicontinuous Nanospheres. Doctor of Philosophy (PhD) thesis, University of Kent,.

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Abstract

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. 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 (DSMA), which has a higher melting point. Upon self-assembly the PEO-b-PDSMA (25 wt % PEO) formed bicontinuous nanospheres. Analysis using differential scanning calorimetry (DSC) revealed the Tm of PEO-b-PDSMA in bulk and aggregate solution to be 41.3°C and 41.1°C respectively.

To further demonstrate the control achieved over the Tm, random copolymers of ODMA and DSMA using a PEO macroinitiator were synthesised at varying wt % ratios of PODMA:PDSMA. DSC analysis of these polymers showed that an increase in PDSMA led to an increase in the Tm for the bulk and self-assembled samples. The controlled release of Ibuprofen from these bicontinuous nanospheres was investigated to determine the rate of release and the optimum temperature for release following a previously used method. The concentration of release was then analysed using HPLC.

To incorporate acid functionality into the bicontinuous nanospheres PMAA-b-PODMA (poly(methacrylic acid)-block-poly(octadecyl methacrylate)) was synthesised (via ATRP) with hydrophilic wt % of 20 %. The self-assembled solution of PMAA-b-PODMA was analysed using cryo-TEM which revealed the presence of bicontinuous nanospheres. Another approach to incorporate acid functionality into bicontinuous nanospheres was the self-assembled of PEO-b-PS and PEO-b-PODMA followed by the alkaline hydrolysis of PEO to leave an acid end group.

Item Type: Thesis (Doctor of Philosophy (PhD))
Thesis advisor: Holder, Simon
Uncontrolled keywords: Polymer Chemistry Self-Assembly Nanospheres Micelles Block Copolymers
Subjects: Q Science > QC Physics
Divisions: Faculties > Sciences > School of Physical Sciences
Depositing User: Users 1 not found.
Date Deposited: 10 Oct 2016 11:00 UTC
Last Modified: 01 Aug 2019 10:40 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/57833 (The current URI for this page, for reference purposes)
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