聚四氟乙烯和聚二甲基硅烷的链尺寸和偶极矩  

DIMENSION AND DIPOLE MOMENT OF POLY(TETRAFLUOROETHYLENE) AND POLY(DIMETHYLSILYLENE) CHAINS

作　　者：马海珠[1] 孙婷婷[1] 

机构地区：[1]浙江工商大学信息与电子工程学院

出　　处：《高分子学报》2010年第4期442-448,共7页Acta Polymerica Sinica

基　　金：浙江工商大学引进人才科研启动项目(项目号1120XJ030813)资助

摘　　要：基于改进的旋转异构态方法,推导了对称双取代基高分子链的均方回转半径和均方偶极矩公式,用于研究聚四氟乙烯(PTFE)、聚二甲基硅烷(PDMS)和聚乙烯(PE)链构象依赖的性质.计算得到长链聚四氟乙烯PTFE4(四态模型)和PDMS的构型参数值分别为0.44·mol0.5·g-0.5和0.43·mol0.5·g-0.5,PDMS链的相应温度系数值-7.32×10-3K-1,它与PTFE和PE的值(约-1.00×10-3K-1)相差较大.得到长链PTFE和PDMS的均方电偶极矩特征比结果都很小,如PDMS链的特征比为0.27,说明虽然PTFE和PDMS的侧基键C—F和Si—CH3都有强极性,但其聚合物却是非极性的电介质,具有较好的电绝缘性能,可见高分子链的构象和结构也对聚合物极性和电学性质有很大的影响.得到短链PTFE和PDMS(重复单元x<10)均方偶极矩表现出明显的端点效应,特征比随x的改变而呈现明显的波动,这与Flory等的计算结果一致.A study of the mean-square radius of gyration and mean-square dipole moment of the symmetric disubstituted polymers is presented basing on the improved rotational-isomeric-state method. The deduced formulas are used to investigate the conformation-dependent properties of poly（ tetrafluoroethylene） （ PTFE）, poly（dimethylsilylene） （ PDMS） and polyethylene （ PE） chains. Here,the configuration parameters of the PTFE4 （PTFE of the 4-state model） chain and PDMS chain are calculated to be about 0. 44 ·mol0. 5·g -0. 5 and 0. 43 ·mol0. 5·g -0. 5 respectively for large polymerization degree x. However,the temperature coefficient of PDMS chain-7. 32 × 10 -3 K -1 is different obviously from that of PTFE and PE chains （about- 1. 00 × 10-3 K -1）. The calculated characteristic ratios of mean-square dipole moment for long PTFE and PDMS chains are rather small,such as the ratio of PDMS is 0. 27. The results show that PTFE and PDMS are non-polar polymers,good dielectric and poor in induction,even though the dipole moments of C—F and Si—C are large in PTFE and PDMS chains. Therefore,the polar and dielectric properties of polymers are also affected by the conformation and structure of chains. In addition,the chain end effect of short PTFE and PDMS chains （repeat unit x 10） results in obvious change of the ratios with x,which is in agreement with the results of Flory et al.

关 键 词：聚四氟乙烯 聚二甲基硅烷 构象 均方偶极矩 构型参数 

分 类 号：O634.41[理学—高分子化学]