PHOTOINITIATED CATIONIC POLYMERIZATION OF EPOXY MONOMERS IN THE PRESENCE OF POLY(3,4-EPOXY-1-BUTENE)

ABSTRACT

Hydroxyl-terminated poly(3,4-epoxy-1-butene) (polyEPB) is an interesting and highly useful agent for the acceleration of the photoinitiated cationic ring-opening polymerization of epoxide monomers. Kinetic investigations using real-time infrared spectroscopy have shown that the observed acceleration of the polymerization is due to two independent mechanisms. Crosslinking polymerization of epoxide monomers is accelerated due to an activated monomer mechanism that results in facile chain transfer due to interaction of the terminal hydroxyl groups of polyEPB with the growing oxonium ion chain ends. A second mechanism involving participation of polyEPB in a free radical chain induced decomposition of the onium salt photoinitiator is mainly responsible for the observed acceleration in the rate of polymerization. A large number of polymer-bound carbocationic species are generated by this mechanism that are capable of initiating polymerization of the epoxide monomer.     

INVESTIGATION OF THE USE OF POLY(3,4-EPOXY-1-BUTENE) IN FREE RADICAL PHOTOPOLYMERIZATIONS

ABSTRACT

The use of poly(3,4-epoxy-1-butene) (polyEPB) in photoinduced free radical polymerizations has been investigated. It was observed that the inclusion of polyEPB into these photopolymerizations has several beneficial effects. In combination with aromatic ketones, polyEPB functions as a hydrogen donor to form a highly effective photoinitiator for the polymerization of acrylate monomers. At the same time, polyEPB undergoes facile autoxidation that serves to mitigate inhibition effects due to oxygen during free radical photopolymerizations. PolyEPB is an effective chain transfer agent that tends to increase both the rate and conversion in photoinduced crosslinking polymerizations in which multifunctional monomers are employed. Lastly, polyEPB is a interesting matrix-modifying agent that becomes incorporated into the resin matrix during photopolymerization due to photoinduced grafting reactions.     

1,3-戊二烯阳离子聚合过程中环化反应的研究

以ＡｌＣｌ３和（ＣＦ３ＳＯ３）３Ａｌ为引发剂，ＣＨ２Ｃｌ２为溶剂，在２０℃聚合了１，３ 戊二烯（ＰＤ）．对聚合物（ＰＰＤ）的结构分析表明，（ＣＦ３ＳＯ３）３Ａｌ生成的聚合物具有较高的环化度．聚合物的环化过程是通过两种机理，分子内链转移机理和阳离子引发机理，后者可以通过加入ＤｔＢＰ得到抑制．ＡｌＣｌ３引发的聚合反应中环化过程以前一种机理为主，而（ＣＦ３ＳＯ３）３Ａｌ则以后一种机理为主．通过阳离子引发的环化反应主要发生在ＰＰＤ１，２单元侧基双键上     

STUDY ON CATIONIC RING-OPENING POLYMERIZATION MECHANISM OF 3-ETHYL-3-HYDROXYMETHYL OXETANE

ABSTRACT

Cationic ring-opening polymerization of 3-ethyl-3-hydroxylmethyl oxetane was carried out using BF₃·O(C₂H₅)₂ as initiator, and a branched polyether was formed. Typical SEC curves show that the polymer consists of two fractions: one has higher molecular weight (11.7×10⁴～ 9.2×10⁴) and the other has lower molecular weight (3.8×10³～4.0×10³). This probably resulted from the chain-tran sfer reaction of two propagating polymer chains. The structure of the polyEHMO formed was characterized by ¹H and ¹³C NMR spectra. The degree of branching is mainly affected by the propagation mechanism. As the molar ratio of [I]₀/[EHMO]₀ in feed increased, the degree of branching also increased.     

STUDY ON THE CATIONIC POLYMERIZATION OF 1, 3-PENTADIENE INITIATED BY AlCl_3/ALKYL HALIDE SYSTEMS

The cationic polymerizations of 1, 3-pentadiene were initiated by AlCl_3 in n-hexaneat 30℃ in the presence of alkyl halides, i.e., tert-butyl chloride, tert-butyl bromide andisobutyl chloride. The effects of these halides on the polymer yield, molecular weight,crosslinking reaction, cyclization and polymer microstructure, have been investigated. Twomain side reactions, crosslinking and cyclization, were suppressed and reduced by theaddition of the halides. The proportion of 1, 4 units of polymer chains was increasedby the presence of the halides, which reduced the polymer yield and the molecular weightof polymers.     

用钛系载体催化剂进行1-丁烯聚合的研究

研制不同组分的载体钛系高效催化剂,考察在不同聚合条件及外加芳酯的情况下对1-丁烯聚合的影响。用催化剂TiCl_4,Ti(OBu)_4/φ_2SiCI_2/苯甲酸乙酯(EB)/MSCl_2/AlEt_3进行1-丁烯聚合具有高的催化活性(3.2×10~4g·PB/g·Ti·h),外加对-甲基苯甲酸乙酯时可提高聚合物等规度(Ⅰ.Ⅰ％=93.3),分子量可用H_2调节。衰减聚合反应的动力学方程为R_1=R_5+(R_0-R_5)e~(βt)。用DSC、WAXD和~(13)C-NMR等方法表征聚合物。     

MeOH/BF_3体系引发异丁烯阳离子聚合反应中水含量及聚合温度的影响

研究了水含量和聚合反应温度Tp 对MeOH BF3体系引发异丁烯 (IB)阳离子聚合反应的转化率、产物的分子量及分子量分布的影响 ,求出在不同水含量条件下的Tp 对聚合物分子量影响的数学方程及相应的聚合度活化能Ep ,以期对体系中存在的微量水加以充分利用 .结果表明 ,[H2 O]和Tp 两者共同影响IB阳离子聚合反应过程及产物的分子参数 .当Tp 由 - 10 0℃升高至 - 5 0℃时 ,聚合转化率先增加到一定值后再减小 ,在- 80℃～ - 70℃范围内出现峰值 .在 [H2 O]较低时 ,Tp 明显影响着聚合产物的分子量及分子量分布 ,Tp 越低 ,分子量越高 ,分子量分布越窄 ;在 [H2 O]较高时 ,Tp 对分子量的影响程度较小 ,说明此时水对聚合反应的影响更为突出 .体系中水含量增大对IB阳离子聚合反应呈现不利作用 ,当 [H2 O]由 1 5× 10 - 3mol L增加至 4 6×10 - 3mol L时 ,Ep 由 - 4 0kJ mol增大至 - 17kJ mol ,说明随着 [H2 O]增大 ,水的负面效应更加明显 ,既促进副反应 ,又阻碍链增长反应 ,增长活化能增大 ,聚合物分子量降低 ,分子量分布变宽 .水的负面作用也随着Tp 升高而变得明显 .     

聚醋酸乙烯酯和共聚物大分子引发剂引发异丁烯正离子接枝共聚合反应

以AIBN为引发剂,通过自由基聚合方法先合成一定分子量(Mn=1.9×104g mol)和分子量分布(MWD,Mw Mn<2.5)的聚醋酸乙烯酯(PVAc)和醋酸乙烯酯(VAc)与醋酸异丙烯酯(IPAc)的无规共聚物聚(PVIPA).再以PVAc或PVIPA作为大分子引发剂,与共引发剂TiCl4配合,引发异丁烯进行正离子接枝共聚反应,并分别考察大分子引发剂用量、TiCl4浓度以及添加剂2,6二叔丁基吡啶(DtBP)或2甲基吡啶(MPY)对异丁烯聚合转化率和PVIPA或PVAc引发效率的影响,并进一步表征接枝共聚物的微观结构与组成含量.实验结果表明,PVIPA和PVAc可引发异丁烯进行正离子接枝共聚反应,前者的引发效率高于后者.加入适量DtBP或MPY时,可不同程度地提高引发效率.DtBP对减少聚合体系中微量水的引发和提高PVAc引发效率的作用更为明显,引发效率可达90%以上,加入适量添加剂MPY时,PVIPA引发效率可达60%左右.适当增加大分子引发剂用量和TiCl4浓度,也可提高PVIPA的引发效率至接近70%.在合适的实验条件下,可以得到极性主链为PVIPA与非极性支链为聚异丁烯(35.2%mol)的接枝共聚物PVIPA g PIB,该接枝共聚物的Mn为3.7×104g mol,分布指数MWD为2.52,且PIB支链平均分子量约为5.4×103g mol.     

含氮试剂对P-DCC／AICl3引发异丁烯正离子聚合的影响。

以对-二枯基氯（DCC），Alcl，体系引发异丁烯在二氯甲烷（CH2C12）正己烷（Hex）（40／60，V／V）混合溶剂中进行正离子聚合，探讨了DCC用量、含氮试剂2，6-二叔丁基吡啶（DtBP）和三苯胺（TPA）对异丁烯正离子聚合转化率、产物分子量及其分布的影响．结果表明，DCC和体系中微量水均可与A1C1，产生竞争络合，形成两种活性中心并引起相继的竞争引发，聚合产物的GPC谱图呈双峰分布，分子量分布宽；增加DCC用量有利于DCC与A1C1，的络合，致使链增长反应主要通过DCC与A1C1，络合形成的活性中心引发，但聚合产物分子量相对较低，分子量分布较宽；使用DtBP，可有效地抑制微量水引发及活性链向单体的转移反应，使分子量分布明显变窄，基本实现DCC的控制引发；采用DtBP与TPA共同调节聚合反应，可使聚合产物分子量分布变窄的同时，进一步提高分子量，从而得到相对较高分子量（Mw=103200）和单峰分子量分布（Mw／Mn=2．09）的聚异丁烯产物．     

含氮试剂对p-DCC/AlCl_3引发异丁烯正离子聚合的影响

以对-二枯基氯(DCC)/AlCl3体系引发异丁烯在二氯甲烷(CH2Cl2)正己烷(Hex)(40/60,V/V)混合溶剂中进行正离子聚合,探讨了DCC用量、含氮试剂2,6-二叔丁基吡啶(DtBP)和三苯胺(TPA)对异丁烯正离子聚合转化率、产物分子量及其分布的影响.结果表明,DCC和体系中微量水均可与AlCl3产生竞争络合,形成两种活性中心并引起相继的竞争引发,聚合产物的GPC谱图呈双峰分布,分子量分布宽;增加DCC用量有利于DCC与AlCl3的络合,致使链增长反应主要通过DCC与AlCl3络合形成的活性中心引发,但聚合产物分子量相对较低,分子量分布较宽;使用DtBP,可有效地抑制微量水引发及活性链向单体的转移反应,使分子量分布明显变窄,基本实现DCC的控制引发;采用DtBP与TPA共同调节聚合反应,可使聚合产物分子量分布变窄的同时,进一步提高分子量,从而得到相对较高分子量(Mw=103200)和单峰分子量分布(Mw/Mn=2.09)的聚异丁烯产物.     

阳离子聚合合成聚苯乙烯大分子单体

<正> 近十年来,对大分子单体的合成和表征进行了较广泛的研究,其中尤以聚苯乙烯大分子单体研究得更多。Milkovich等用阴离子聚合合成了一系列具有不同端基的大分子单体。本文采用实验要求比阴离子简单的阳离子聚合方法,用对-氯甲基-β-溴乙苯和三     

(CH_3)_3SiOSO_2CF_3/SbCl_3阳离子引发体系引发1,3-戊二烯聚合

研究了三氟甲基磺酸三甲基硅酯／三氯化锑（（ＣＨ３）３ＳｉＯＳＯ２ＣＦ３／ＳｂＣｌ３）复合引发体系对１,３ 戊二烯的聚合行为．在（ＣＨ３）３ＳｉＯＳＯ２ＣＦ３引发剂中加入ＳｂＣｌ３后,使聚合反应速率提高了２４倍,产率从（ＣＨ３）３ＳｉＯＳＯ２ＣＦ３引发的５５％提高到８０％以上,分子量提高１７倍．在聚合体系中加入酮类后,产率和分子量相对于（ＣＨ３）３ＳｉＯＳＯ２ＣＦ３／ＳｂＣｌ３配比为０２：１时引发所得聚合物均呈下降趋势;但对不同的酮来说,随着酮的位阻的增大,聚合物的产率和分子量均增大．聚合物的１Ｈ ＮＭＲ图和红外谱图数据均证明该聚合反应是通过（ＣＨ３）３ＳｉＯＳＯ２ＣＦ３与体系中残存的水水解所形成的质子酸ＨＯＳＯ２ＣＦ３与ＳｂＣｌ３反应所形成的复合体系引发进行的．     

CATIONIC POLYMERIZATION OF 1, 3—PENTADIENE INITIATED BY ORGANIC AZIDE/Et2AlCl

The cationic polymerization of 1, 3-pentadiene was initiated by the organic azide/Et_2 AlClinitiating system in CH_2Cl_2 and n-hexane. The polymerizations were also carried out in parallelwith organic chloride/Et_2AlCl and Et_2 AlCl alone for comparison. The Et_2 AlCl- induced polymer-ization gives a low yield while the polymerization initiated by organic chloride/Et_2 AlCl producesmainly insoluble product. In contrast, the polymerization with azide/Et,AlCl has a high conver-sion and the resulting polymer having a high molecular weight is totally soluble. The SEC spectraof the polymers have clearly shown the differences between these initiating systems.     

STUDY ON THE MECHANISM OF 1-OCTENE ZIEGLER-NATTA POLYMERIZATION BASED ON THE NUMBER OF ACTIVE CENTERS

The number of active centers (C_p)-t and k_p-t profiles of Solvay type TiCl_3 - AlR_3 (R=C_2H_5, i-C_4H_9) or Stauffer AA TiCl_3-Al (C_2H_5)_3 catalyzed 1-octene polymerization were determined by using an acetyl chloride quenching method as well as kinetic data. The results show that in the studied systems k_p decreases when C_p increases, indicating the presence of two or more types of different active centers. The C_(p~(-t)) plots of the Solvay TiCl_3-AlR_3 systems show the presence of both stable active centers and unstable centers which decay in the polymerization process. The phenomena are explained based on a model of active center plurality. The increases of C_p in the induction periods are also discussed.     

(CH3)3SiCl/TiCl4 INITIATING SYSTEM FOR CATIONIC POLYMERIZATION OF 1,3-PENTADIENE

Cationic polymerizations of 1,3-pentadiene (PD) initiated by trimethylsilyl chloride (TMSCl) incombination with TiCl_4 were carried out in n-hexane at 30℃. The yield of polymer was greatly increased bythe addition of TMSCl, indicating that the TMSCl/TiCl_4 combination is an efficient initiating system for PDcationic polymerization. However, the introduction of TMSCl gave rise to a drop in the molecular weight ofthe polymer. Kinetic results demonstrated that the polymerization initiated by TMSCl/TiCl_4 is 4.5 times fasterthan that induced by TiCl_4 alone. Various ethers were used to mediate the TMSCl/TiCl_4 initiating system.Adding diphenyl ether could increase both the yield and molecular weight of the polymer. Structural evidenceillustrates that the polymerization is indeed initiated by TiCl_4 in combination with HCl resulting fromhydrolysis by adventitious water.     

ROLE AND IMPORTANCE OF RADIUS OF GYRATION OF CHAINS IN THE MELT IN THE CRYSTALIZATION OF POLY(1-BUTENE)

Crystallization in polymer systems actually is a process that transfers the entangled melts into a semi-crystallinelayered structure. Whether or not a chain disentangles may result in different crystallization mechanism. When compared tothe crystal thickness (d_c), the volume occupied by the chain in the melt, i.e., the radius of gyration (R_g), plays a veryimportant role in polymer crystallization. When d_c≤R_g, crystallization does not necessitate a chain disentangling. Theentanglements are just shifted into the amorphous regions. However, as d_c>R_g, i.e., as the crystal thickness ges larger thanthe radius of gyration of the chain in the melt, it becomes necessary for a chain to disentangle. Then a change ofcrystallization mechanism occurs. Such change has been experimentally observed in the crystallization of poly(1-butene). Achange in the crystal morphologies from spherulite to quadrangle, is seen via PLM, as crystalliation temperatures increase.Even more, such a change is molecular weigh dependent and shifts to lower temperature as molecular weigh decreases.There exists a jump of crystal thickness and crystallinity associated with morphological change, as seen via SAXS. A changeof crystallization kinetics and crystallinity is further evidenced via dilatometry. The unique feature of P1b crystallization hasbeen discussed based on the radius of gyration of chain in the melt (R_g), and very good agreement is obtained.     

STUDY ON CATIONIC RING-OPENING COPOLYMERIZATION OF 1,4-ANHYDRO-2,3-DI-O-BENZYL-α-D-RIBOPYRANOSE WITH 1,4-ANHYDRO-2,3-O-ISOPROPYLIDENE-α-D-RIBOPYRANOSE

Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization using SbCl_5 or BF_3 OEt_2 as catalyst atlow temperature gave stereoregular (1→4)β-D-ribofuranan (C-1 and C-4 ring cleavagesee Scheme 1) or (1→5) α-D-ribofuranan (C-1 and C-5 ring cleavage) respectively. Theeffects of catalysts, reaction time and temperatures on yield and stereoregularity of the ob-tained polymers were studied. Polymers were characterized by molecular weight, ~1HNMR,~(13)CNMR and optical rotation.     

2-位取代的4-亚甲基-1,3-二氧环戊烷开环聚合反应研究

合成了两种新单体，４ 亚甲基 ２ 苯乙烯基 １，３ 二氧环戊烷和４ 亚甲基 ２ 苯乙烯基 ２ 甲基 １，３ 二氧环戊烷．研究了这两种单体的自由基和阳离子聚合反应．根据聚合物的红外光谱和核磁共振碳、氢谱，确定了聚合物的结构，讨论了聚合反应机理，特别对２ 位取代基对聚合反应和产物的影响作了初步的探讨．     

NH-1分离5''-核苷酸的研究

针对4种5’-核苷酸(AMP、GMP、CMP和LIMP)的理化特性，合成了一种新的阳离子交换树脂NH-1．研究了4种5’-核苷酸在NH-1树脂上的分离度，优化了工艺条件．实验结果发现：当上柱液pH为2．2、上柱量0．02g／ml-resin，上柱及洗脱线速度0．5m／h，高径比15：l时，4种物质间的分离度均大于10，分离总收率大于93％，UMP的纯度为80％左右，其余3种纯度均在95％以上．     

紫外光引发丙烯酰胺分散聚合研究

以聚丙烯酸接枝壬基酚聚氧乙烯(PAA -g -NPEO)作分散剂,紫外光(UV)引发丙烯酰胺(AM )在叔丁醇 水(TBA /H2 O)体系中进行了分散聚合.考察了聚合反应特征以及醇水比、初始单体浓度、引发剂浓度、分散剂浓度、表面入射光强、反应温度、液层厚度等参数对聚合产物粒径及分子量的影响.结果表明该聚合体系不存在诱导期,反应速度快,光照4 0min转化率可达到90 % ,产物分子量达6 . 5×10 6 .透射电镜(TEM)观察显示所得聚合物粒子基本为球形,粒径分布较为均匀.