CHAIN TRANSFER-REACTION IN THE POLYMERIZATION OF SUBSTITUTED ACETYLENES .2. CHAIN TRANSFER-REACTION TO TRIMETHYLVINYLSILANE IN THE POLYMERIZATION OF DISUBSTITUTED ACETYLENES BY MOCL5-N-BU4SN
H. Kouzai et al., CHAIN TRANSFER-REACTION IN THE POLYMERIZATION OF SUBSTITUTED ACETYLENES .2. CHAIN TRANSFER-REACTION TO TRIMETHYLVINYLSILANE IN THE POLYMERIZATION OF DISUBSTITUTED ACETYLENES BY MOCL5-N-BU4SN, Journal of polymer science. Part A, Polymer chemistry, 31(7), 1993, pp. 1887-1893
The effect of various olefins as chain transfer agents was studied in
the polymerization of 1-chloro-1-octyne, 1-chloro-2-phenylacetylene, 2
-octyne, etc., catalyzed by MoCl5-n-Bu4Sn (1:1). Si-containing olefins
, especially trimethylvinylsilane, greatly lowered the polymer molecul
ar weight in the polymerization of the Cl-containing acetylenes, e.g.,
the M(n)BAR Of poly(1-chloro-1-octyne) was 4.2 X 10(5) without an ole
fin, whereas it decreased to 3.4 X 10(4), i.e., below 1/10 in the pres
ence of trimethylvinylsilane (1/2 equiv to monomer). In contrast, the
molecular weight of poly(2-octyne) did not decrease that much, even wi
th trimethylvinylsilane. The Cl-containing polyacetylenes obtained in
the presence of trimethylvinylsilane as chain transfer agent possessed
the trimethylsilyl group. Thus, the present study enables control of
the molecular weight of substituted polyacetylenes by chain transfer,
and further verifies the metal carbene mechanism for the polymerizatio
n of substituted acetylenes.