화학공학소재연구정보센터
Journal of Polymer Science Part A: Polymer Chemistry, Vol.43, No.21, 5119-5126, 2005
Novel siloxane-carrying dithiol derived from 5-membered cyclic dithiocarbonate and its curing reactions for coating application
A new efficient and straightforward method to convert amines into siloxane-thiol hybrid molecules was developed. The method relies on the nucleophilic addition of amines to a cyclic dithiocarbonate having siloxane moiety (DTC-Si), and the successive ring-opening reaction of the dithiocarbonate moiety to give the corresponding acyclic thiourethane having a thiol moiety. Based on this method, amine-terminated poly(propylene glycol) was successfully transformed into the corresponding polyether having thiol-terminals and siloxane groups. In the presence of moisture, the alkoxysilyl moiety underwent condensation reaction to make the polyether cured into a transparent resin having solvent-resistance. Addition of bisphenol A diglycidyl ether (Bis A-DGE) to the curing process resulted in two simultaneous reactions, i.e., (1) condensation of siloxane part and (2) addition reaction of the thiol terminal and the epoxide group. When this curing process was carried out on a glass surface, the siloxane part reacted with silanol group on the surface, forming a coating layer having excellent mechanical toughness graded as maximum 7H by pencil toughness test (JIS-K5400). (c) 2005 Wiley Periodicals, Inc.