Amphiphilic Polymer Conetworks: Experiment and Theory

Amphiphilic polymer conetworks (APCN) [1] comprise covalently cross-linked hydrophilic and hydrophobic segments, and are consequently capable of microphase separating upon transfer into a selective solvent like water [2].  Thus, these materials represent the network analogs to surfactants.  While currently evaluated in various emerging applications in biomedicine and technology, with a notable example in the latter area that of their use as matrices for gel or solid polymer electrolytes in re-chargeable batteries, APCNs are credited with a major real-market application, with global annual sales totaling 10 billion US dollars.  This is their use as silicone hydrogel soft contact lenses, in which the carefully selected hydrophilic and hydrophobic segments, as well as their microphase separated morphology, impart to the lens important properties related to eye comfort and oxygenation [3].

Our latest APCNs are carefully formed by end-linking well-defined polymer segments involving, in most cases, an amphiphilic block copolymer or a hydrophobic homopolymer, and a hydrophilic four-armed linker [4,5].  Dynamic covalent acylhydrazone links are employed so as to allow APCN self-healing and recycling, thereby extending materials service life and reducing environmental footprint [6].  Characterization of the self-assembled structures, via scattering, and the mechanical properties in water identifies the APCNs with the largest domain sizes, longest-range ordering and greatest extensibility, providing various choices to the applications engineer to select among materials with a broad spectrum of attributes.  These experimental results on morphology and mechanical properties are complemented by and compared to the results of thermodynamic modeling and dissipative particle dynamics simulations [7].  We expect that our work will lay the foundation for the design and development of next-generation APCNs.