Recent literature has suggested that siloxane-polyurethane segmented copolymers can be synthesized from the reaction of a silanol terminated poly(dimethylsiloxane) (PDMS) with a diisocyanate.  However, literature published in the early 1960s as well as expert opinion in the fields of silicon and isocyanate chemistry has suggested that the silyl carbamate linkage is hydrolytically unstable, and readily decomposes in the presence of water into carbon dioxide, silanol and amine. But, there are no definitive studies in the recent literature. Investigation into this reaction was carried out using silanol-terminated PDMS and aliphatic and aromatic diisocyanates (TDI, H12MDI, MDI, IPDI, and HMDI) as well as monoisocyanates (cyclohexyl isocyanate and phenyl isocyanate). Outgassing of carbon dioxide from the reaction was measured. Once synthesized, analysis of the product using FTIR, 1H NMR, GPC and MS provide insight into product formation, as well as the hydrolytic stability upon exposure to water.

Is the silanol-isocyanate reaction suitable for forming stable siloxane-polyurethane block copolymers?

247th National Meeting (2014)

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