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Emulsion-templated polymerizations are an attractive route to prepare porous materials that possess broad tunability by controlling the features of the emulsion template. Emulsion templated polymer materials possessing shape memory behavior have also been reported, usually using (meth)acrylate monomers. However, achieving shape memory properties in emulsion templated materials with polymers that do not possess accessible thermal transitions, including polydimethylsiloxane (PDMS), remains challenging. Here, porous PDMS materials have been prepared with stearic acid within the continuous phase of the emulsion template. The inclusion of stearic acid imparts the material with a transition temperature of ∼70 °C, and the porous materials in this work obtained fixity >90% and recovery >95% over multiple shape memory cycles. These results demonstrate how low glass-transition temperature emulsion-templated polymer materials can easily be given shape memory properties. This work should be a starting point for studies of elastomeric emulsion-templated polymer materials in applications, including in soft robotics.
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Synthesis and Applications of Elastomeric Polymerized High Internal Phase Emulsions (PolyHIPEs)
Polymer foams (PFs) are among the most industrially produced polymeric materials, and they are found in applications including aerospace, packaging, textiles, and biomaterials. PFs are predominantly prepared using gas-blowing techniques, but PFs can also be prepared from templating techniques such as polymerized high internal phase emulsions (polyHIPEs). PolyHIPEs have many experimental design variables which control the physical, mechanical, and chemical properties of the resulting PFs. Both rigid and elastic polyHIPEs can be prepared, but while elastomeric polyHIPEs are less commonly reported than hard polyHIPEs, elastomeric polyHIPEs are instrumental in the realization of new materials in applications including flexible separation membranes, energy storage in soft robotics, and 3D-printed soft tissue engineering scaffolds. Furthermore, there are few limitations to the types of polymers and polymerization methods that have been used to prepare elastic polyHIPEs due to the wide range of polymerization conditions that are compatible with the polyHIPE method. In this review, an overview of the chemistry used to prepare elastic polyHIPEs from early reports to modern polymerization methods is provided, focusing on the applications that flexible polyHIPEs are used in. The review consists of four sections organized around polymer classes used in the preparation of polyHIPEs: (meth)acrylics and (meth)acrylamides, silicones, polyesters and polyurethanes, and naturally occurring polymers. Within each section, the common properties, current challenges, and an outlook is suggested on where elastomeric polyHIPEs can be expected to continue to make broad, positive impacts on materials and technology for the future.
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- Award ID(s):
- 1904518
- PAR ID:
- 10540144
- Publisher / Repository:
- ACS
- Date Published:
- Journal Name:
- ACS Omega
- Volume:
- 8
- Issue:
- 23
- ISSN:
- 2470-1343
- Page Range / eLocation ID:
- 20178 to 20195
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1021/acsomega.3c01265
