ネットワークポリマー
Online ISSN : 2186-537X
Print ISSN : 1342-0577
ISSN-L : 1342-0577
Steric Effect of Long-Chain Alkyl Groups on Network Formation in the Free-Radical Crosslinking Copolymerizations of Alkyl Methacrylates with Trimethylolpropane Trimethacrylate
Akira MATSUMOTOKeiichi FUJISEJun-ichi IKEDAHiroyuki AOTA
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ジャーナル フリー

2002 年 23 巻 2 号 p. 81-91

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This article deals with the steric effect of long-chain alkyl groups on network formation in the free-radical crosslinking copolymerizations of alkyl methacrylates (RMA) including hexyl methacrylate, lauryl methacrylate, and stearyl methacrylate (SMA) with trimethylolpropane trimethacrylate (TMPTMA). The incorporation of one TMPTMA unit into a copolymer chain corresponds to the introduction of two or one methacryloyl group, i.e., noncyclic structure unit having two methacryloyl groups or monocyclic structure unit having one methacryloyl group, respectively, and thus, TMPTMA acts as an effective crosslinker. The initial rate of polymerization and primary polymer chain length increased with an increase in the size of the alkyl group in RMA from hexyl to stearyl; this is ascribed to the reduced occurrence of bimolecular termination. The increasing tendency of degree of polymerization with conversion was suppressed in the same order. The deviation of the actual gel point from the theoretical one became greater with enlarged chain of alkyl groups, especially for the copolymerization with SMA. These are related to the suppressed occurrence of the intermolecular crosslinking reaction of sterically crowded growing methacrylyl radical with the pendant methacryloyl groups embedded in the preformed poly (RMA-co-TMPTMA).
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© Japan Thermosetting Plastics Industry Association
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