Synthesis of a New Type Both-End-Capped Poly(oxymethylene) with a Long Alkyl Group

Hajime NAGAHARA, Keisuke YAJIMA and Junzo MASAMOTO*

Department of Polymer Science and Engineering, Kyoto Institute of Technology; Matsugasaki, Sakyo-ku, Kyoto-shi 606-8585 Japan
Chemistry & Chemical Process Laboratory, Asahi Chemical Industry Co., Ltd.; Kojimashionasu, Kurashiki-shi 711-8510 Japan

A new type both-end-capped poly(oxymethylene) with a long alkyl group was synthesized. Using formaldehyde methyl octadecyl acetal as the chain transfer agent for the polymerization of trioxane, the both-end-capped poly(oxymethylene) with a methoxy group and octadecyloxy group was obtained. Almost all the formaldehyde methyl octadecyl acetal in the polymerization mixture is consumed. Formaldehyde methyl octadecyl acetal is confirmed to be chemically bonded in poly(oxymethylene) derived from 1H-NMR measurements. For the case of using formaldehyde di(octadecyl) acetal as the chain transfer agent, almost all the formaldehyde di(octadecyl) acetal in the polymerization mixture is consumed. Direct proof that formaldehyde di(octadecyl) acetal is chemically bonded in poly(oxymethylene) was obtained. The reduced viscosity of the polymer showed a complicated behavior. This suggested that some aggregation of the octadecyl group of the polymer chain-end took place in the solution. For the case using formaldehyde methyl acetal of the carbon number 38 alcohol, the polymer obtained showed the melting behavior at 95 °C, which could be attributed to the melting of the long alkyl group. The reduced viscosity also suggested an aggregation of the long alkyl group of the polymer chain end in the solution. The observed amount of the C38H77 group, which was calculated from the observed value of methylene linkage by 1H-NMR, was lower than the calculated value based on the feed C38H77OCH2OCH3. This fact suggests that the methylene linkage of the C38H77 group may provide a strong aggregation in the solution.

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