Self-Assembly and Characterization of Block Copolymer Aggregates with a Range of Potential Applications

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The work focuses on block copolymer (BC) self-assembly in solution, to yield micelles, rods and especially vesicles, which combine relatively small size with space suitable for loading of both hydrophobic and hydrophilic materials; release profiles will be studied.  Other areas are the formation of nano-particles (NPs), their encapsulation and precise localization within BC aggregates (of interest in catalytic applications). 1) Layer-by-layer (LBL) assembly of various aggregates in sequential multilayers to yield planar nanostructures containing oppositely charged aggregate layers. Large vesicles can also serve as the base structure with surrounding alternating layers of oppositely charged small vesicles and/or micelles to create multilayered nano-capsules resembling blackberries. These structures are of potential interest in catalysis and in the controlled release of multiple ingredients. Thus, one could incorporate different catalytic species into different layers to attempt sequentially catalyzed reactions within a thin layer format. 2) Precise localization of nanoparticles (NPs). Since success has been achieved with symmetric localization of NPs, it is now proposed to explore precise asymmetric localization, e.g. still within a vesicle wall, but closer to one of the interfaces than the other (internal or external). This would be of interest for vesicles in which the exterior and interior interfaces contain different corona chains. Other possibilities include the localization of one type of NP in the hydrophobic center of the vesicle wall or micelle core, with another NP localized at the interior/exterior interface of the vesicle or at the micelle interface. This would be of special interest for for possible use in catalysis. 3) Filling and release of agents from BC aggregates. Multi-component release will be explored from either single systems containing two or more ingredients or from planar or spherical assemblies with the different components in different layers. Interacting components would be of interest under conditions where the combined system has a limited lifetime and the release rate needs to be slow. 4) Morphological control in biocompatible and biodegradable polymers. Release properties from recently prepared lamellar structures will be compared with those from spherical aggregates. Upon successful completion, the proposed research will allow us to design systems capable of controlled release of ingredients from sub-micron size aggregates. If desired it may be possible for those ingredients to undergo catalyzed chemical reactions in the release process under conditions were product degradation on storage may be a problem. Potential applications, with special benefits to Canada, include release (and catalysis) in agricultural or pharmacological settings.