Determination of low critical surface tensions of novel fluorinated poly(amide urethane) block copolymers .3. Siloxane-containing side chains

Low critical surface tensions (CST's) of novel copolymers containing a ''hard block'' polyurethane and a ''soft block'' polyamide with siloxane side chains are reported. The hard segment consists of methylenebis(cyclohexyl isocyanate) (H(12)MDI) and butanediol or a fluorinated analog. The soft, segment contains a diacid chloride and secondary siloxane-containing diamines. The different diamines studied were N,N'-bis[3-(pentamethyldisiloxyl)propyl]-1,6-diaminohexane, N,N'-bis[3-(heptamethyltrisiloxyl)propyl]-1,6-diaminohexane, and N,N'-bis[3-(poly(dimethylsiloxyl)propyl]-1,6-diaminohexane. hexane. The two diacid chlorides studied were hexafluoroglutaryl chloride and adipoyl chloride. The polyamide oligomers were synthesized from different combinations of these diamines and diacid chlorides. Films of the segmented copolymers were examined by contact angle measurements with water, and CST's were determined from contact angles of water and methylene iodide. Poly(amide urethanes) containing PDMS side chains displayed high advancing and high receding water contact angles and maintained this hydrophobicity when exposed to water for 30 days.