【作者】 邓杭军；

【导师】 陈纪忠；

【作者基本信息】 浙江大学 ， 化学工程， 2014， 博士

【摘要】 聚四氢呋喃(PTHF)是制备聚氨酯弹性体、氨纶等的重要原料,广泛应用于汽车、医疗器械和纺织等领域。为解决传统液体酸引发剂存在的废液排放、设备腐蚀和引发剂难以回收等问题,目前,固体酸引发剂成为研究热点。本文以环氧氯丙烷(ECH)为促进剂、以磷钨酸(HPW)为引发剂引发四氢呋喃(THF)开环聚合,首次采用在线红外技术监测了聚合反应过程,研究了THF开环聚合反应动力学,系统考察了聚合反应条件参数,重点分析和探讨了链转移剂乙二醇(EG)对聚合反应和聚合产物分子量的影响,并开展了HPW在SBA-15介孔分子筛上的负载化研究。论文主要包含以下内容：(1)基于在线红外技术研究了THF开环聚合反应过程,以1068和1109cm-1醚键特征峰分别对THF在二氯甲烷(CH2C12)中聚合过程的单体THF和聚合物PTHF变化进行实时监测。结果表明：THF在CH2C12溶剂中的开环聚合反应符合一级可逆动力学模型,其表观一级链增长速率常数kapp(kapp=kp×[P*])增大随引发剂浓度增大不成比例；通过不同温度下的单体平衡浓度[M]。,获得热力学参数为△Hp=-3.9kcal·mol-1、.△Sp=-15.3cal·mol-1·K-1,聚合上限温度Tc(标准状态)为155K；通过不同温度下的kapp,获得表观活化能为Ea=44.53kJ·mol-1;较高的聚合反应温度(15或25℃)使得链转移反应加剧,导致聚合后期存在偏离一级可逆反应现象。(2)针对THF开环聚合中聚合反应条件对其聚合反应及其聚合产物分子量具有较大影响,论文以EG为链转移剂,通过正交设计试验法系统考察了聚合温度、聚合时间、ECH、HPW和EG等因素对PTHF产率和数均分子量(Mn)的影响,尤其是链转移剂EG对聚合反应和聚合物分子量的影响,并深入研究了链转移剂对聚合反应的影响机制。结果表明：聚合体系中引发剂与促进剂存在协同作用；通过引入EG作为链转移剂,有效地控制了PTHF的Mn,从12000-23000降低至1100-1700,并使分子量分布(MWD)明显变窄,由双峰分布变为单峰分布；EG的加入可有效控制链增长,抑制“回咬”反应的发生,减少聚合过程中带环体聚合物的生成;同时,聚合体系传质效率的较高使得聚合物产率从50%提高至80%左右。此外,当聚合体系中有少量EG(mEG/mTHF=1.25×10-2～2.51×10-2)时,链转移剂可促进聚合反应；而当体系中有较多EG(mEG/mTHF=3.76×10-2～7.52×10-2)时,链转移剂会抑制聚合反应,单体平衡浓度随mEG/mTHF增大而增大。(3)为制备孔径较大的载体用于负载磷钨酸多相引发THF开环聚合,选取对二甲苯(PX)为胶束膨胀剂,以三嵌段共聚物P123为模板剂水热合成得到SBA-15介孔分子筛,通过控制合成条件(PX/P123质量比mPX/mP123、晶化温度和引入电解质NH4F),合成了可控孔径(6-30nm)的SBA-15。结果表明：SBA-15介孔分子筛孔径随着mPX/mP123增大而增大,但介孔材料的有序度会有所降低,而提高晶化温度和引入电解质NH4F均可以有效提高扩孔剂PX的扩孔作用。(4)以所合成的SBA-15为载体负载HPW,用于多相引发THF开环聚合。重点考察了HPW负载质量百分比wHPW、3-氨丙基三乙氧基硅烷(APTES)/SBA-15质量比mAPTES/mSBA-15和载体SBA-15孔径、比表面积等因素对引发剂的活性和THF转化率的影响。结果表明：采用直接浸溃法负载HPW,最优wHPW为40%；将SBA-15进行氨基改性后负载HPW,最优mAPTES/mSBA-15为0.0712,通过氨基改性可有效改善引发剂的重复使用性能；当载体SBA-15的比表面积较大(853m2.g-1)或孔径较大(比表面积较小,498-585m2·g-1)时,所制备的引发剂具有较高的引发效率、聚合产物的Mn较高,引发剂的引发效率和聚合产物分子量随着孔径增大而增大。更多还原

【Abstract】 The polytetrahydrofuran (PTHF) is an important chemical material of elastomeric polyurethanes and spandex fibre, which is widely used in automotive industry, medical apparatus, textile industry and so on. Aiming at solving the problems of waste liquid discharge, equipment corrosion and difficult recycling of initiators, solid acid becomes a research hot spot at the present time. In this article, the THF polymerization was initiated by phosphotungstic heteropolyacid (HPW) using epichlorohydrin (ECH) as promoter. In-situ FT-IR was first applied for monitoring of the THF polymerization process, which provided full insight into the reaction kinetics. And effects of different factors on THF polymerization were systematically investigated. The influence of ethylene glycol as chain transfer agent on THF polymerization and the molecular weight (Mn) of PTHF product were emphatically studied. Furthermore, HPW was supported on the mesoporous SBA-15for heterogeneous catalysis in THF polymerization. It contains following parts:(1) The polymerization of THF carried out in CH2Cl2was monitored by in-situ mid-infrared spectroscopy system (ReactIR). The changes in absorbance intensity of the two characteristic peaks at1068and1109cm-1were used for monitoring the monomer and polymer, respectively. The experimental results demonstrated that the increase of apparent first-order rate constant kapp (kapp=kp×[P*]) for propagation is disproportional to the increase of HPW concentration and the THF polymerization reaction proved to be typically first-order reversible reaction. Thermodynamic parameters are determined to be△Hp=-3.9kcal·moF-1,△SP=-15.3cal·mol-1·K-1, Tc=155K from the temperature dependence of the monomer equilibrium concentration [M]e. And the ceiling temperature at standard state is determined to be155K. Also the apparent activation energy is determined to be Ea=44.53kJ·mol-1from the temperature dependence of kapp. Besides, it is confirmed that more chain-transfer occurred at higher temperatures (15or25℃), leading to a deviation from first-order propagation at the later stage of polymerization.(2) Considering that various reaction conditions have great influence on THF polymerization reaction and the Mn of PTHF, effects of various factors (polymerization temperature and time, content of ECH, HPW and EG) on the yield and Mn of PTHF were systematically investigated based on a L16(45) orthogonal experimental design using ethylene glycol (EG) as chain transfer agent. It was found that the initiator and promoter have synergistic effects on THF polymerization. The addition of EG as chain transfer agent in THF polymerization can effectively control the chain propagation and depress the back-biting reaction. In the presence of EG, cyclic fraction obviously diminishes in the resulted PTHF and its Mn decreases from12000～23000to1100～1700. Also PTHF’s MWD is significantly narrowed changing from unimodal distribution into single peak distribution. Moreover PTHF’s yield increases from50%to80%because of its higher mass transfer efficiency. It was also found that a trace amount of EG (mEG/mTHF=1.25×10-2～2.51×10-2) will slightly promote polymerization, while a large amount of EG (wEG//wTHF=3.76×10-2～7.52×10-2) will restrain polymerization, resulting in higher [M]e of THF.(3) In order to support HPW on the porous materials with larger pore size for THF polymerization, mesoporous silica SBA-15with tunable pore size (6-30nm) was synthesized through simple control of synthetic variables (/wPX/mP123, hydrothermal crystallization temperature and the addition of NH4F) using p-xylene (PX) as micelle expander and triblock copolymer as template agent. The results demonstrated that the increase of/mPX/wP123will expand the pore size and reduce the order degree of SBA-15. It suggested that the higher hydrothermal crystallization temperature and the addition of NH4F will lead to more efficient swelling of PX and subsequent pore expansion.(4) The initiator prepared by supporting HPW on mesoporous SBA-15was applied in THF polymerization. Effects of mass fraction of HPW (wHpw), mass ratio of APTES to SBA-15(/mAPTES/mSBA-15), the pore size and specific surface area of SBA-15on the performance of initiators and the conversion of THF were investigated. It was found that the supported initiator HPW/SBA-15prepared by impregnation with40%mass fraction of HPW exhibits highest activity. The amino-functionalized SBA-15can effectively improve the performance of HPW/SBA-15-NH2for repeated use in THF polymerization. And the initiator HPW/SBA-15-NH2has highest activity when the mass ratio of mAPTES/mSBA-15is0.0712. The initiator shows good performance in THF polymerization. PTHF product has higher molecular weight when SBA-15has higher specific surface area (853m2·g-1) or larger pore size (lower specific surface area,498～585m2·g-1). The performance of initiator and the Mn of PTHF increase with the pore size of SBA-15.更多还原