窄分子量分布端羟基聚四氢呋喃的合成与表征

以高氯酸为催化剂,乙酸酐为促进剂及分子量调节剂,通过四氢呋喃阳离子开环聚合合成了分子量可控且分子量分布较窄(Mw/Mn1.2)的聚四氢呋喃,聚合产物端部含有乙酸酯基,经醇解后得到端羟基聚四氢呋喃(PTMEG)。探讨了聚合时间、高氯酸用量、乙酸酐用量、溶剂对聚四氢呋喃分子量(Mn)及分子量分布(Mw/Mn)的影响。研究表明,延长聚合时间、增加高氯酸及乙酸酐的用量均会造成Mn先升后降,但只有聚合时间对Mw/Mn会造成显著的影响,聚合时间为4h时Mw/Mn最小;加入CH2Cl2溶剂会降低聚四氢呋喃的Mn及Mw/Mn。采用凝胶渗透色谱-多角度激光散射联用仪(SEC-MALLS)对聚合产物的Mn及Mw/Mn进行了准确地测定,应用FT-IR、1 H-NMR表征了端羟基聚四氢呋喃大分子结构,利用DSC及TG研究了其热性能,结果表明,端羟基聚四氢呋喃的熔点及分解温度随着Mn的增加略有升高。

Synthesis and Characterization of Hydroxyl-terminated Polytetrahydrofuran with Narrow Molecular Mass Distribution

Polytetrahydrofuran with narrow molecular mass distribution was prepared by cationic ring-opening polymerization of tetrahydrofuran using perchloric acid as a catalyst and acetic anhydride as a promotor which also can be regarded as a molecular mass regulator.As the polymerization product contains a considerable amount of terminal acetate group,it should be subjected to alcoholysis for preparing pure hydroxyl-terminated polytetrahydrofuran(PTMEG).The effects of reaction time,the dosage of perchloric acid and acetic anhydride and solvent on molecular mass(Mn) and molecular mass distribution(Mw/Mn) were studied by size exclusion chromatography and multi-angle laser light scattering(SEC-MALLS).The study showed that with the increase of polymerization time,dosage of perchloric acid and acetic anhydride,Mn of polymerization product rised at first and lowered later;reaction time was the most important effect factor for Mw/Mn,when reaction time was 4h,Mw/Mn could be minimum;when solvent was added in this reaction system,Mn and Mw/Mn decreased.The macromolecular structure of hydroxyl-terminated polytetrahydrofuran was characterized by FT-IR and 1H-NMR and the thermal property of PTMEG was studied by DSC and TG.The result indicated that the melting point and decompose temperature of hydroxyl-terminated polytetrahydrofuran increases slightly with Mn.