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Self-Assembly and Ordering of Degradable Polymers

The self-assembly of polymers is an important area of study for the generation of nanomaterials that can be applied in a wide range of fields from drug and gene delivery to bionanocomposite materials. In the biomedical arena the incorporation of degradable polymers (ideally sources from natural materials) is highly attractive as the materials will be able to degrade to innocuous byproducts after their role has been completed. The group is particularly interested in controlling the morphology and stability of the self-assembled particles by taking advantage of the inherent stereochemistry of many of the monomers (and hence polymers) that we study. To this end, we are focussed on using crystallization to drive self-assembly towards the realization of cylindrical nanoparticles, a morphology that is hard to access in a pure form using conventional methods yet which has potentially great advatanges in drug delivery and nanocomposite materials. Furthermore, the use of ‘simple’ diblock copolymer systems to create stable nanoparticles through stabilization without the requirement for elegant yet complex cross-linking stabilization strategies.

Recent Highlights:
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Nanosponge formation from organocatalytically synthesized poly(carbonate) copolymers (ACS Macro Lett. 2012, 1, 915)

Here, we demonstrated that the use of advanced organocatalytic synthesis methods enabled the synthesis of poly(carbonate)s with control over functional group incorporation and molecular weight. Pendant allyl or epoxide groups were used as reaction partners in thiol-ene click or epoxide–amine reactions to form poly(carbonate) nanosponges via an intermolecular chain-crosslinking approach.

Cylindrical Micelles of Controlled Length from the Crystallization-Driven Self-Assembly of Poly(lactide)-Containing Block Copolymers (Chem. Sci. 2011, 2, 955)

In this work poly(lactide)-b-poly(acrylic acid) was synthesized using a combination of ring-opening polymerization and reverse-addition fragmentation chain transfer (RAFT) polymerization. Interestingly, self-assembly of block copolymers of this type in which the PLA component was enantipure homochiral PLLA or PDLA resulted in the isolation of cylindrical nanoparticles by a simple direct dissolution methodology. Such morphologies are hard to access and may have significant benefits in nanoparticle systems for drug-delivery.

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Stereocomplexation in novel degradable amphiphilic block copolymer micelles of poly(ethylene oxide) and poly(benzyl α-malate) (Soft Matter, 2011, 7, 10987)

In this paper we demonstrated that clock copolymers of ethylene oxide and enantiopure monomers derived from malic acid (BMA) enabled self-assembly to nanoparticles that displayed stabilities that were highly dependant on the stereochemistry of the polymers. Notably, equimolar mixtures of PEO-b-P(L-BMA) and PEO-b-P(D-BMA) resulted in micelles with increased stability compared to micelles formed from either enantiopure block copolymer. This methodology could have significant benefits in the facile synthesis of stabilized nanoparticles.

We have published review articles in several areas related to our research, a summary of these articles can be found here.


Polymerisation Catalysis

Synthesis of Functional Degradable Polymers from Sustainable Resources

Self-Assembly and Ordering of Degradable Polymers

Development of Novel Degradable Biomaterials