【摘要】：本文合成了4-甲基苯并12-冠-4咪唑卡賓(B12C4imY)和2,3,6,7-四氫-5H-噻唑并[3,2-a]嘧啶(ITU)兩種有機(jī)催化劑。在聚乙二醇(PEG)作大分子引發(fā)劑的條件下,用卡賓催化劑B12C4imY和ITU與鹵化鎂(MgX2)的共催化劑(ITU/Mg X2)分別催化ε-己內(nèi)酯(CL)開(kāi)環(huán)聚合,制備了三嵌段共聚物PCL-PEG-PCL。系統(tǒng)地探索了嵌段聚合反應(yīng)的特征,得到了反應(yīng)的最佳條件。利用NMR、IR、GPC和DSC測(cè)試手段表征了聚合物的結(jié)構(gòu)、分子量及熱性能,并推測(cè)了可能的聚合機(jī)理。在四氫呋喃(THF)溶液中,以PEG為引發(fā)劑,B12C4imY催化CL開(kāi)環(huán)聚合,合成了PCL-PEG-PCL三嵌段共聚物。通過(guò)對(duì)聚合時(shí)間、溫度、催化劑用量、單體濃度和引發(fā)劑用量等條件的研究,得到該共聚反應(yīng)的最適條件:[M]=3.0 mol/L,[M]/[C]=300,[M]/[I]=200,25℃下,反應(yīng)40 min,CL的轉(zhuǎn)化率高達(dá)96.8%。在此條件下所得聚合物的分子量(Mn)和分子量分布(PDI)分別是:Mn=3.68×104 g/mol,PDI=1.47。1H NMR和IR分析證明了共聚物的結(jié)構(gòu),推測(cè)該反應(yīng)的機(jī)理為“單體-活化”機(jī)理。三嵌段共聚物的DSC曲線顯示在64.3℃有一個(gè)熔融峰。用PEG作為大分子引發(fā)劑,將ITU/Mg X2體系用于CL的開(kāi)環(huán)聚合,制備了分子量較高且分子量分布較窄的三嵌段共聚物PCL-PEG-PCL。實(shí)驗(yàn)表明ITU/Mg X2體系是催化內(nèi)酯開(kāi)環(huán)聚合的有效催化劑。用1H NMR,13C NMR,IR,GPC,DSC等分析手段對(duì)聚合物的結(jié)構(gòu)與熱性能進(jìn)行了表征與分析。實(shí)驗(yàn)得到了以下結(jié)論:1.用PEG和ITU/Mg X2催化體系引發(fā)CL開(kāi)環(huán)聚合,當(dāng)[M]=2.0 mol/L,[M]/[C]=80,[M]/[I]=200,30℃下,在THF中反應(yīng)12 h可以得到Mn為6.6×104 g/mol,PDI為1.43的三嵌段共聚物。2.通過(guò)NMR和IR測(cè)試手段對(duì)PCL-PEG-PCL的結(jié)構(gòu)進(jìn)行了分析,并推斷出聚合反應(yīng)的機(jī)理。GPC測(cè)試得到了聚合物的Mn和PDI值,PCL-PEG-PCL的GPC曲線為單峰,與PCL相比,曲線向高分子量方向移動(dòng)。通過(guò)DSC測(cè)試方法對(duì)PCL、PEG以及PCL-PEG-PCL的熱性能進(jìn)行了對(duì)比,研究表明,PEG段的引入使得聚合物的熔融溫度和結(jié)晶溫度都有明顯提升。
[Abstract]:Two kinds of organic catalysts, 4-methylbenzo-12-crown-4 imidazole carbene (B12C4imY) and 2H3H3H- tetrahydro-5H-thiazolyl (ITU), have been synthesized in this paper. The ring-opening polymerization of 蔚 -caprolactone (CL) was carried out with carbene catalyst B12C4imY and ITU and magnesium halide (MgX2) co-catalyst (ITU/Mg X2) under polyethylene glycol (PEG) as macromolecular initiator. Triblock copolymer PCL-PEG-PCL. was prepared. The characteristics of block polymerization were systematically explored and the optimum reaction conditions were obtained. The structure, molecular weight and thermal properties of the polymer were characterized by NMR,IR,GPC and DSC, and the possible polymerization mechanism was deduced. PCL-PEG-PCL triblock copolymers were synthesized by ring-opening polymerization of CL catalyzed by B12C4imY in tetrahydrofuran (THF) solution with PEG as initiator. By studying the polymerization time, temperature, amount of catalyst, monomer concentration and initiator dosage, the optimum conditions for the copolymerization were obtained: [M] = 3.0 mol/L, [M] / [C] = 300, [M] / [I] = 200,25 鈩，

本文編號(hào)：2365884