Bioactive Hybrid Organogels Based on Miniemulsion Synthesis of

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Bioactive Hybrid Organogels Based on Miniemulsion Synthesis of Morphologically Complex Polymer/Surfactant/Calcium Phosphate Nanostructures Khrongkhwan Akkarachaneeyakorn, Mei Li, Joe Harris, Sean A. Davis, and Stephen Mann* Centre for Organized Matter Chemistry and Centre for Protolife Research, School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom S Supporting Information *

ABSTRACT: Morphologically complex amorphous calcium phosphate nanostructures are synthesized within supersaturated water-in-oil miniemulsions stabilized by a mixture of a calcium bis(2-ethylhexyl)phosphate (Ca(DEHP)2) surfactant and poly(ethylene oxide)19-poly(propylene oxide)69-poly(ethylene oxide)19 (P123) triblock copolymer. Solvent evaporation at room temperature results in self-supporting viscous organogels comprising an interconnected network of calcium phosphate nanofilaments embedded within a continuous polymer/surfactant matrix. The P123/DEHP/calcium phosphate organogels are employed as a bioactive filler for the occlusion of exposed dentine tubules using a standard bovine tooth model.

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INTRODUCTION Auxiliary agents such as hydrophilic and amphiphilic polymers, self-assembled micelles, and water-in-oil microdroplets have been extensively used to control the structure, morphology, and higher-order organization of inorganic nanostructures.1,2 For example, alkylated double-hydrophilic poly(ethylene oxide)poly(methacrylic acid) block copolymers (PEO-b-PMAA-C12) have been employed in the synthesis of calcium phosphate nanofilaments with unusual neuron-like morphology,3 and double-hydrophilic block copolymers used to prepare barium sulfate materials with peanut-like and flower-like architectures.4,5 Numerous studies involving confined reaction media in the form of water-in-oil droplets of various dimensions (