Starch/Silicone Elastomers and Foams

Abstract

While the beneficial physical properties of silicone polymers are exploited in many sustainable applications, the high energy requirement for their synthesis compromises to a degree their sustainability. We report a strategy to mitigate this issue by filling the silicone with inexpensive and renewable starch. Elastomeric materials with covalently grafted starch, utilizing anhydride-modified silicones, permits loading of up to about 75% starch while maintaining many of the properties of the silicone. Alternatively, 50 wt.% starch-filled silicone foams can be prepared simply by mixing powdered starch with a mixture of HSi-functional silicone fluids in the presence of B(C6F5)3. The physical properties of the resulting foams are determined by the quantity of SiH, which controls the final density of the foams (ranging from 0.258–0.875 g mL−1), their Young’s modulus, and their degree of elasticity; both rigid and flexible foams were prepared. Materials with a high natural and renewable material content better adhere to green chemistry principle 7, should enhance the ease of degradation at end of life, and augment the sustainability of these silicone composites.

Functional silicone oils and elastomers: new routes lead to new properties

“…16B). 61 The products are surprisingly resistant to water; little change was seen after boiling in water for 3 days.…”

“…60 An analogous process has recently been described to create thermoplastic silicone elastomers. 61,62 6.3 Other click reactions without catalysts 6.3.1 Aza-Michael reaction: amino acid silicones. The aza-Michael involves addition of an amine to a wide variety of readily available acrylates and related structures without the need for a catalyst.…”

“…60 An analogous process has recently been described to create thermoplastic silicone elastomers . 61,62…”

Tris(pentafluorophenyl)borane-catalyzed Hydride Transfer Reactions in Polysiloxane Chemistry—Piers–Rubinsztajn Reaction and Related Processes

“…They were able to mix a mixture of SiH-functional silicone fluids with 50 wt.% starch powder and catalytic amounts of TPFPB. The resulting mixture was converted into a cross-linked starch–silicone hybrid foam in a few minutes, using the dehydrogenating condensation of Si-H groups with alcohol groups present on the starch molecule [ 146 ].…”