Silicone elastomers with improved hydrophilicity are prepared by equilibrating dimethylsiloxane - ethylene oxide block copolymer (PEO-PDMS) with cross-linked polydimethylsiloxane (PDMS) in the presence of base.  Siloxane equilibration is implicated as the grafting mechanism. The poly(ethylene oxide) (PEO) segments are chemically attached to the elastomer, as shown by contact angle, ATR-IR and XPS measurements. Characterization with TGA revealed that there is only a small amount of PEO chains grafted to the cross-linked PDMS. The PEO chains can aggregate on the surface as indicated in AFM images of dried samples. The modified silicone elastomers, with PEO-PDMS grafted both 'onto' and 'into' the elastomer, maintain their hydrophilicity apparently indefinitely. This simple, one-step silicone modification method can be applied to PDMS cross-linked by either anionic copolymerization or hydrosilylation.  The resulting modified silicones may be valuable materials for microfluidic devices and microcontact printing stamps.

Silicone modification using siloxane equilibration

247th National Meeting (2014)

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