화학공학소재연구정보센터
Macromolecules, Vol.31, No.22, 7575-7580, 1998
Living anionic polymerization of 1-(alkoxy)ethyl methacrylates and the preparation of well-defined poly(methacrylic acid)
Three novel methacrylate monomers, 1-(ethoxy)ethyl methacrylate (EEMA), 1-(butoxy)-ethyl methacrylate (BEMA), and 1-(tert-butoxy)ethyl methacrylate (tBEMA), were prepared through the addition reaction of methacrylic acid (MAA) and ethyl, butyl, or tert-butyl vinyl ether, respectively. These monomers have been subjected to anionic polymerization in tetrahydrofuran (THF), using (1,l-diphenyl)-hexyllithium (DPHL) as initiator. In contrast to the common alkyl methacrylates, their anionic polymerizations were very sensitive to temperature and to the amount of LiCl added. A [LiCl]/[DPHL](0) molar ratio of unity was most beneficial, but a high excess of LiCl had a negative effect. Suitable polymerization temperatures were found to be in the range -60 to -20 degrees C, with an optimum at about -40 degrees C, but even at +20 degrees C tBEMA could be polymerized quantitatively to a poly(tBEMA) with a relatively narrow molecular weight distribution (M-w/M-n = 1.18). However, the very low temperature of -80 degrees C, which is optimum for the common alkyl methacrylates, was not suitable for the new monomers. For [LiCl]/[DPHL](0) approximate to 1 and a temperature in the range -60 to -20 degrees C, the anionic polymerizations of EEMA, BEMA, and tBEMA could proceed in a living manner and generate polymers with controlled molecular weights and narrow molecular weight distributions (M-w/M-n = 1.06-1.09). Poly(EEMA), poly(BEMA), or poly(tBEMA) could be easily hydrolyzed, to generate well-defined poly(MAA).