PolyHIPEs are porous emulsion-templated polymers that are usually synthesized within surfactant-stabilized water-in-oil high internal phase emulsions (HIPEs). Typical polyHIPEs have highly interconnected porous structures and low bulk densities. Surfactant-free polyHIPEs can be synthesized through the formation of nanoparticle-stabilized Pickering HIPEs. Temperature-responsive shape memory polymer (SMP) foams based on acrylates and methacrylates with crystallizable side-chains exhibited fixity ratios of 1.0 for compressive strains of 70 % and relatively high recovery ratios. In these SMP foams, the recovered structure is identical to the original structure seen in Figure 1a following quite extensive deformation, as seen for a compressive strain of 65 % in Figure 1b. Changing the type of stabilization, crosslinking strategy, locus of initiation, or polymerization mechanism produced profound differences in the porous microstructure and in the SMP properties. While the methacrylate-based SMP exhibited a single-stage recovery, the acrylate-based SMP, with identical side-chains, exhibited a two-stage recovery associated with the individual thermal transitions of two different crystalline phases. The recovery behavior was described using Kelvin-Voigt units in series with the dependence of viscosity on temperature described using a WLF-like relationship. SMP foams that respond rapidly in aqueous environments were produced by simultaneously polymerizing a hydrogel (HG) in the HIPE's aqueous internal phase and forming HG-coated polyHIPEs.

Shape memory polymer foams through emulsion-templating

249th National Meeting (2015)

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