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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 8, Number 2
February 20, 1987 

Syntheses of Alternating Head-to Head Vinyl Copolymers and Vinyl Terpolymers via Ring-Opening Mechanism. Ring-Opening Polymerization of Substituted-3,4-dihydro-2H-pyrans
Ju-Yeon Lee, Iwhan Cho
2-Ethoxy-6-methoxy-5-cyano-3,4-dihydro-2H-pyran (1a), 2-n-butoxy-6-methoxy-5-cyano-3,4-dihydro-2H-pyr an (1b), 2-isobutoxy-6-methoxy-5-cyano-3,4-dihydro-2H-py ran (1c), and 2-ethoxy-6-methoxy-3-methyl-5-cyano-3,4-dihydro -2H-pyran (1d) were prepared by (4 + 2) cycloaddition reaction of methyl α-cyanoacrylate with the corresponding alkyl vinyl ethers. Compounds 1a-d were ring-open polymerized by cationic catalyst to obtain alternating head-to-head (H-H) copolymers. For comparison, head-to-tail (H-T) copolymer 3a was also prepared by free radical copolymerization of the corresponding monomers. The H-H copolymer exhibited minor differences in its 1H NMR and IR spectra, but in the 13C NMR spectra significant differences were observed between the H-H and H-T copolymers. Glass transition temperature (Tg) of H-H copolymer was higher than that of the H-T copolymer, but thermal decomposition temperature of the H-H copolymer was lower than that of the H-T copolymer. Compounds 1a, ab, and 1c, copolymerized well with styrene by cationic catalyst, but compound 1d failed to copolymerize with styrene. All of the H-H and H-T copolymers were soluble in common solvents and the inherent viscosities were in the range 0.2-0.4 dl/g.
96 - 101
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