SYNTHESIS AND PROPERTIES OF POLY[ISOBORNYL METHACRYLATE (IBMA)-B-BUTADIENE(BD)-B-IBMA] COPOLYMERS - NEW THERMOPLASTIC ELASTOMERS OF A LARGE SERVICE TEMPERATURE RANGE

摘要

Anionic polymerization of isobornyl methacrylate (IBMA) has been studied in THF and toluene in a temperature range from -78 to +40 degrees C by using (1,1-diphenyl-3,3-dimethylbutyl)lithium (DDBLi) as an initiator in the presence of LiCl or not. Effect of solvent and polymerization temperature on tacticity has been studied. The reactivity of IBMA is comparable to tert-butyl methacrylate (tBMA), and polymers of a very narrow molecular weight distribution (<1.10) have been synthesized at room temperature, in THF, in the presence of LiCl. The T-g of PIBMA is found to vary from 170 to 206 degrees C with chain tacticity. Poly(isobornyl methacrylate) (PIBMA)-polybutadiene (PBD)-PIBMA triblock copolymers have been synthesized by using the m-diisopropenylbenzene (m-DIB)/tert-butyllithium (t-BuLi) diadduct as an initiator. The PBD midblock has been prepared in a cyclohexane/diethyl ether (100/6, v/v) mixture at room temperature. THF has been added [cyclohexane/diethyl ether/THF (100/6/100, v/v/v)] before the IBMA polymerization takes place at either -78 or +25 degrees C. Triblock copolymers of a very narrow molecular weight distribution (1.10) have been synthesized even at 25 degrees C, and no gel formation has been observed. These new triblock copolymers exhibit high tensile strength (30 MPa), high ultimate elongation (1000%), and high upper service temperature (160 degrees C). [References: 29]