【作者】 朱伟伟；

【导师】 沈之荃； 倪旭峰；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2010， 博士

【摘要】 联烯是一类具有连续双键结构的化合物,在聚合反应中两个连续双键能够选择性地打开进行聚合,得到侧链上带有可反应双键的聚合物。通过联烯聚合物中双键的反应可以制备结构新颖的功能高分子材料,因此联烯的聚合研究越来越被重视。本论文首次采用稀土及钛金属催化剂成功制备得到正辛基、正辛氧基联烯均聚物以及联烯/苯乙烯共聚物,详细研究了聚合规律和特征,探讨了聚合机理,表征了聚合物的组成、结构与性能,研究探索了基于联烯共聚物的功能高分子的合成与性能。研究发现,稀土膦酸酯盐Ln(P204)3与Al(i-Bu)3组成二元催化体系可在温和条件下催化正辛基联烯聚合。其中Y(P204)3/Al(i-Bu)3体系催化的正辛基联烯的聚合行为具有一定的活性聚合特征,产物的分子量可控且分子量分布较窄。通过氯化稀土与席夫碱钠盐的交换反应制备了一系列以3,5-二叔丁基水杨醛缩苯胺为配体的稀土席夫碱配合物。用IR,EA及X射线单晶衍射表征了其中的钕席夫碱配合物的结构,发现该配合物具有独特的五角双锥构型。上述稀土席夫碱配合物Ln(Salen)3与Al(i-Bu)3组成双组份催化体系,可以催化正辛氧基联烯聚合,聚合动力学研究表明该聚合反应过程具有一定的可控性。进一步研究发现,其中的Y(Salen)3/Al(i-Bu)3体系也可催化正辛氧基联烯与苯乙烯共聚合。考察了所制备的稀土席夫碱配合物单组份催化ε-己内酯开环聚合的规律和特征,结果表明ε-己内酯在该催化剂作用下能可控开环聚合。采用简便的方法合成了3,5-二叔丁基水杨醛缩苯胺席夫碱钛配合物Ti(Salenl)2Cl2,发现Ti(Salenl)2Cl2与Al(i-Bu)3组成的二元催化体系是催化正辛基联烯均聚合以及正辛基联烯与苯乙烯共聚合的优良催化剂。系统研究了该体系催化正辛基联烯/苯乙烯的共聚合规律,优化了聚合条件,提出了配位插入的共聚合机理：Ti(Salenl)2Cl2/Al(i-Bu)3不能催化苯乙烯均聚合,而正辛基联烯与配合物中心钛原子的配位作用使苯乙烯能够插入到聚合物链中实现共聚合。首次引入巯基与双键加成反应(Thiol-ene reaction),分别采用"grafting-from"和"grafting-onto"的方法实现对正辛基联烯/苯乙烯共聚物的接枝改性,制备得到具备新型结构的共聚物。小分子含巯基化合物如巯基乙醇与联烯共聚物反应后,将羟基引入到共聚物中作为大分子引发剂,用Sn(Oct)2引发己内酯开环聚合,得到正辛基联烯-苯乙烯-聚己内酯三元接枝共聚物(PALST-g-PCL).详细研究了PALST-g-PCL的组成、结构与性能；联烯聚合物与巯基乙酸反应将羧基引入到共聚物PALST中,通过羧基与羟基的耦合反应制备得到两亲性接枝共聚物(PALST-g-PEG),并表征了它们的结构与性能；还通过一步反应将端基为巯基的PEG大分子接枝到正辛基联烯/苯乙烯共聚物主链上,制备得到两亲性接枝共聚物(PALST-g-PEG).更多还原

【Abstract】 Allene derivatives have cumulated double bonds, either part of the cumulated double bonds can be polymerized selectively to obtain polymers having reactive exomethylene substituents. The possibility reactions for the vinyl double bonds indicate the potential applicability of polymers from allene derivatives as novel functional materials. The homopolymerization of n-octylallene, n-octyloxyallene and copolymerization of the allenes with styrene by rare earth catalysts or titanium complex were studied. The influences of reaction conditions on the polymerization, the characteristics, kinetics, and the mechanism of the polymerizations were investigated. The structure and the properties of the polymers obtained were characterized.Polymerization of n-octylallene was successfully carried out using a conventional binary rare earth catalytic system composed of rare earth tris(2-ethylhexylphosphonate) (Ln(P204)3) and tri-isobutyl aluminum (Al(i-Bu)3) for the first time. The effects of solvent, reaction time and temperature on the polymerization of n-octylallene by Y(P204)3/Al(i-Bu)3 were studied. The resulting poly(n-octylallene) has weight-average molecular weight of 11000, molecular weight distribution of 1.4 and 96% yield under the moderate reaction conditions:[Al]/[Y]=50 (molar ratio), [n-octylallene]/[Y]=100 (molar ratio), polymerized at 80℃for 20h in bulk. The poly(n-octylallene) obtained consists of 1,2- and 2,3-polymerized units, and was characterized by FT-IR,’H-NMR and GPC. Further investigation shows that the polymerization of n-octylallene has some living polymerization characteristics preparing the polymer with controlled molecular weight and narrower molecular weight distribution.Lanthanide Schiff-base complexes with the formula of [3,5-tBu2-2-(O)C6H2CH=NC6H5]3Ln(THF) (Ln=Sc, Y, La, Nd and Gd) have been synthesized by metathesis reaction of anhydrous LnCl3 with Schiff-base sodium salt in good yields. The complex with neodymium center was characterized by X-ray diffraction, the geometry around neodymium atom could be described as pentagonal bipyramid. It was found that the rare earth catalytic systems composed of Ln(Salen)3 and Al(i-Bu)3 are efficient for the homopolymerization of n-octyloxyallene, and show some characteristic of controlled polymerization; Y(Salen)3/Al(i-Bu)3 catalytic system can initiate the copolymerization of n-octyloxyallene with styrene. The ring-opening polymerization (ROP) ofε-caprolactone (CL) was successfully carried out by using these lanthanide Schiff-base complexes as catalysts, and neodymium complex leads to controlled ROP of CL. The influence of the reaction conditions on the monomer conversion, molecular weight, and molecular weight distribution of the resultant polymers was investigated. The polymerization rate was first-order with respect to the monomer concentration.Complex [Ti(salen)2Cl2] was synthesized with high yield by reacting the Schiff-base ligand with TiCl4 in n-hexane. This titanium Schiff-base complex combined with Al(i-Bu)3 has high catalytic performance for the polymerization of n-octylallene. The optimum reaction conditions for the polymerization are:[n-octylallene]/[Ti]=100, [Al]/[Ti]=50, aged at 80℃for 1h, polymerized at 80℃for 16h in bulk, and the Poly(n-octylallene) obtained has 100% yield, Mw=6.6×104, MWD=1.77 and 50% 1,2-polymerized units. Poly(n-octylallene-co-styrene) (PALST) was prepared from the copolymerization of n-octylallene and styrene with high yield by using the coordination catalyst system composed of Ti(salen)2Cl2 and Al(i-Bu)3. The molar ratio of each segment in the copolymer, and the molecular weight of the copolymer as well as the microstructure of the copolymer could be adjusted by varying the feeding ratio of both styrene and n-octylallene. A coordination-insertion mechanism was proposed for the copolymerization of n-octylallene and styrene.Novel graft copolymers consisting of poly(n-octylallene-co-styrene) (PALST) as backbone were synthesized using "grafting-from" or "grafting-onto" approaches based on thiol-ene reaction. The hydroxyl functionalized copolymer PALST-OH was prepared by the reaction of mercaptoethanol with the pendant double bond of PALST in the presence of radical initiator AIBN. The graft copolymer [poly(n-octylallene-co-styrene)-g-polycaprolactone] (PALST-g-PCL) was synthesized through a grafting-from strategy via the ring-opening polymerization (ROP) using PALST-OH as macroinitiator and Sn(Oct)2 as catalyst. Structures of resulting copolymer were characterized by means of gel permeation chromatography (GPC) with multi-angle laser light scattering (MALLS),1H NMR, DSC, polarized optical microscope (POM) and contact angle measurements. The amphiphilic graft copolymer PALST-g-PEG was synthesized through a grafting-onto strategy via the coupling reaction between the mercaptoacetic functionalized copolymer PALST-COOH and PEG-OH. Meanwhile, a one-spot strategy was developed for the synthesis of PALST-g-PEG by the thiol-ene reaction of PEG-SH and PALST.更多还原