Hydrogen Bonding Properties of Ether-Based Urethane Prepolymers and Polyurethane Elastomers

Katsuji MATSUNAGA*, Makoto OUMI, Masahiro TAJIMA and Yasuhiko YOSHIDA

Department of Applied Chemistry, Faculty of Engineering, Toyo University; 2100 Kujirai, Kawagoe-shi 350-8585 Japan
Present address: Asahi Denka Kogyo Co. Ltd. Functional Polymer R&D Laboratory; 20, Syowanuma, Syobu-cho, Minamisaitama-gun, Saitama 346-0101 Japan

Isocyanate-terminated urethane prepolymers(ITUP) and polyurethane elastomers(PUE) have been prepared by the reaction of 4,4'-methylenebis(phenyl) diisocyanate with polyether diols such as α-hydro-ω-hydroxypoly(oxypropylene)(PPG) or α-hydro-ω-hydroxypoly(oxytetramethylene)(PTMG) of various molecular weights. Characterization of the ITUP and the PUE has been carried out by means of differential scanning calorimetry and FTIR spectroscopy. In this article, discussion is made with the interaction development between soft and hard segments on the basis of the evaluated glass-transition temperatures(Tg)and the hydrogen bond interaction among the urethane- and the ether-linkages in molecular chain. The Tg values of ITUP and PUE are considerably high in comparison with those of only the PPG and the PTMG. This implies that the micro-Brownian motion of the oxypropylene and the oxytetramethylene moiety is restricted by the hard segment which contains the urethane linkages having a high activity of the hydrogen bond interaction. Physical crosslinks by the hydrogen bond in the ITUP and PUE are formed between the soft segment and the hard segment and between the hard segment and the hard segment, and the degree of crosslinking is higher with the latter. The PPG-based NHC-O-C (%) is higher than the PTMG-based one, whereas the PPG-based NHC=O (%) is lower than the PTMG-based one. Thus rigid hard domain is formed rather with the PTMG-based one.

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