Dipole Moments of Poly(ethylene oxide) and Poly(vinylcrown ether)

1聚环氧乙烷的偶极矩在25~55ﾟC温度范围内，通过测量其稀苯溶液的介电常数和密度，测定了不同分子量聚氧乙烯的偶极矩。在25ﾟC下，单位重复单位的平均偶极矩mU分别为1.037D(M_W=4.6×10^4)，1.039D(M_W=9.5×10^4)，1.038D(M_W=27×10^4)，1.041D(M_W=57×10^4)和1.042D(M_W=86×10^4)(D；德拜单位，MW；平均分子量)。对于所引用的分子量范围，PEO链的MU恒定到0.5%以内。偶极矩比为-lt；mu2&gt；/nm^2=0.47_2*0.00_2(在25ﾟC时)，其中n和m是键偶极数及其偶极矩。五种聚合物样品的平均温度系数为dln&lt；mu^2&gt；/dT=(1.9_4*0.2_7)X10^&lt；-3&gt；K^&lt；-1&gt；.2。聚乙烯基苯并-15-冠-5的合成和介电性能。将邻苯二酚转化为邻苯二酚二乙酸酯，再经Fries重排生成3，4-二羟基苯乙酮(VI)。VI与1，11-二氯-3，6，9-三氧十一烷反应生成4‘-乙酰苯并-15-冠-5(VIII)。在70ﾟC下，以偶氮二(异丁腈)为引发剂，通过自由基聚合法合成了聚乙烯基苯并-15-冠-5，用三端铂电池测得的偶极矩(电池电容：26.485pF)为2.2773D(25ﾟC)。温度系数为dln&lt；mu^2&gt；/dT=1.54X10^&lt；-3&gt；K^&lt；-1&gt；.

1 Dipole moment of poly(ethylene oxide)The dipole moments of poly(ethylene oxide) with different molecular weights were determined from dielectric constant and density measurements performed on their dilute benzene solutions over the temperature range from 25 to 55ﾟC.The Values of average dipole moment per repeat unit, mu, at 25ﾟC were 1.037D (M_W=4.6X10^4), 1.039D(M_W=9.5X10^4), 1.038D(M_W=27X10^4), 1.041D(M_W=57X10^4) and 1.042D (M_W=86X10^4)(D ; debye unit, Mw ; weight average molecular weight). mu for the PEO chains was constant to within 0.5% for the cited range of molecular weight. The dipole moment ratio was calculated as <mu^2>/nm^2=0.47_2*0.00_2(at 25ﾟC), where n and m are number of bond dipoles and their dipole moment. Temperature coefficient averaged for five polymer samples was dln<mu^2>/dT=(1.9_4*0.2_7)X10^<-3>K^<-1>.2 Synthesis and dielectric property of polyvinylbenzo-15-crown-5The preparation of the macromer, 4'-vinylbenzo-15-croun-5(I), is as follows. Catechol was converted to catechol diacetate, followed by a Fries rearrangement which produced 3,4-dihydroxyacetophenone(VI). VI was reacted with 1,11-dichloro-3,6,9-trioxaundecane to form 4'-acetobenzo-15-crown-5(VIII). VIII was reduced with NaBH4 and the resulting alcohol was dehydrated with a trace of p-toluene sulfonic acid to form I. Polyvinylbenzo-15-crown-5 was prepared by radical polymerization using azobis(isobutylonitrile) as initiator at 70 ﾟC. The dipole moment measured in benzene by use of the three terminal platinum cell (cell capacitance : 26.485pF) was 2.2773D(25ﾟC). Temperature coefficient was dln<mu^2>/dT=1.54X10^<-3>K^<-1>.