反应介质对催化链转移聚合反应的影响探究

采用催化链转移聚合法制备得到了端基带双键的聚甲基丙烯酸甲酯(PMMA)大分子单体,通过红外吸收光谱(FT-IR)、核磁共振氢谱(1HNMR)对大分子单体的结构进行了表征,并用凝胶渗透色谱法(GPC)测定了大分子单体的分子量及分子量分布;首次利用碘值法测定了大分子单体的双键含量。实验过程中考察了反应介质及其含量对大分子单体的分子量的影响,结果表明由于催化链转移剂与反应溶剂的络合作用,大分子单体的数均分子量随溶剂含量的增加而变大。     

聚氨酯-丙烯酸酯共聚物动力学的研究

以偶氮二异丁腈为引发剂,合成了以丙烯酸丁酯和甲基丙烯酸甲酯为主链,以聚氨酯为侧链的共聚物,考察了聚合温度、引发剂用量、溶剂含量及大分子单体用量对聚合速率的影响。结果表明,丙烯酸酯封端的聚氨酯预聚体的加入对自由基溶液聚合有一定的影响,共聚体系的表观活化能为39．93kJ／mol,聚合速率同引发剂质量分数的0．278次方成正比,聚合速率在20％溶剂含量时最大。     

双键单封端聚氨酯丙烯酸酯大分子单体的合成及表征

以异佛尔二酮异氰酸酯(IPDI)和聚醚二元醇(PEG)为单体、(甲基)丙烯酸羟乙酯和正丁醇为共封端剂,合成了以双键单封端为主的聚氨酯丙烯酸酯大分子单体.考察了反应条件的影响,对聚氨酯大分子单体进行了表征.结果表明反应温度越高、催化剂用皱越大、封端剂的羟基活性越强,预聚反应和封端反应所需时间越短;聚氨酯人分子单体中双键含量随IPDI与PEG摩尔比的增加而增加.     

聚甲基丙烯酸甲酯非水分散体的合成

以聚醚马来酸酯大分子单体作为分散剂,采用半连续工艺研究了甲基丙烯酯甲酯在120＃汽油／二甲苯溶剂中的分散聚合,制备了粒径0．5－1．5μm、固含量为40％的聚甲基丙烯酸甲酯微粒子分散体。考察了溶剂配比、大分子单体的结构和用量及共聚单体及对该分散体稳定性的影响。     

可聚合助稳定剂聚氨酯-丙烯酸酯复合细乳液的制备

以异佛尔酮二异氰酸酯、聚醚多元醇、1,4-丁二醇、丙烯酸羟乙酯为主要原料制得两端含C=C双键的非离子型聚氨酯预聚体大分子,然后经细乳液聚合法与甲基丙烯酸甲酯和丙烯酸丁酯共聚得到聚氨酯-丙烯酸酯(PUA)复合乳液。通过FT-IR、1H-NMR、TEM、SEM等方法对制备的PUA复合物进行了表征和分析。结果表明:在细乳液聚合中,聚氨酯预聚体大分子具有一定的助稳定作用,单体转化率随其用量的增加而减少;选用油溶性的引发剂制备的复合物PUA的胶粒粒径分布较窄。     

聚三烯丙基异氰尿酸酯的合成研究

采用卤代烃为溶剂和调聚剂,在引发剂存在下,使三烯丙基异氰尿酸酯(TAIC)预聚,制备了一种新型的热固性树脂聚三烯丙基异氰尿酸酯(P-TAIC),其溴值为100g～140g/g,软化点大于200℃。讨论了引发剂、溶剂、单体浓度对预聚反应的影响,测定了预聚反应的平均转化率约为40%,考察了未聚合单体的循环使用情况。     

非离子型聚氨酯-丙烯酸酯复合细乳液的研究

首先通过异佛尔酮二异氰酸酯与聚醚多元醇缩聚,以1,4-丁二醇为扩链剂制得—NCO为端基的非离子型聚氨酯(PU)预聚体大分子,然后分别用乙醇和丙烯酸羟乙酯(HEA)对其封端。经细乳液聚合法与甲基丙烯酸甲酯和丙烯酸丁酯共聚得到聚氨酯-丙烯酸酯(PUA)复合乳液。结果显示:当细乳化时间为5min、细乳化转速为14000r/min以上时,制备出的细乳液较为稳定;随着PU预聚体用量和分子量的增加,聚合反应速率和最终单体转化率都有所下降;并且HEA封端的PU预聚体与MMA和BA形成了交联网络结构。     

专利文摘

一种剥离涂料用聚氨酯乳液的制备方法 本发明涉及一种剥离涂料用聚氯酯乳液的制备方法,该方法包括以下步骤：将大分子多元醇真空脱水后加入二异氰酸酯反应得到小分子预聚体,再加入亲水性扩链剂进行扩链及小分子扩链剂反应,得到大分子树脂,降温后加入中和剂中和,然后加入去离子水进行剪切乳化,最后经真空减压脱除溶剂,得到聚氨酯乳液。     

异氰酸酯预聚体合成工艺的研究

采用H_(12)MDI和IPDI为异氰酸酯单体,聚四氢呋喃为聚醚多元醇,醋酸丁酯为溶剂,配制成异氰酸酯预聚体。讨论了反应原材料、反应温度以及溶剂含水量对反应过程和异氰酸酯预聚体性能的影响。分析了原材料配比与异氰酸酯基含量(—NCO%)和体系黏度的关系,最终确定了异氰酸酯预聚体的最佳合成工艺条件。     

MMA—BA—MAA树脂自由基共聚合成的研究

以过氧化二苯甲酰为引发剂,采用溶液聚合合成了甲基丙烯酸甲酯（MMA）．丙烯酸丁酯（BA）＋甲基丙烯酸（MAA）树脂,通过实验确定了自由基共聚合适宜的单体配比、单体浓度、引发剂浓度、溶剂以及反应的升温速度。该改性后的丙烯酸树脂可作为胶粘剂的大分子固化剂,能提高粘接强度和透明性。     

Polymerization of macromers

Summary The possibility of group transfer polymerization of methyl methacrylate-terminated polystyrene macromer (MA-PSt) was explored by using 1-methoxy-1-(trimethylsiloxy)-2-methyl-1-propene and tris(dimethylamino)sulfonium difluorotrimethylsilicate as initiator and catalyst, respectively. The results obtained at the polymerization temperature of 0°C were undesirable. However, the oligomerization at -78°C gave almost quantitatively oligo(MA-PSt) of which the degree of polymerization was in good agreement with the mole ratio of macromer to initiator. The GPC curve of oligo(MA-PSt) was sharp and symmetrical. In addition, it was shown by the copolymerization with methyl methacrylate that the polymerizability of the macromer was markedly enhanced in the presence of methyl methacrylate comonomer.     

Syntheses and polymerizations of macromers

Summary Living poly(tetrahydrofuran) (PTHF) was coupled with sodium p-vinylbenzyloxide quantitatively to prepare a macromer of p-vinylbenzyloxyl poly(tetrahydrofuran) (VBO-PTHF). The radical polymerization of the macromer with AIBN was performed. From the GPC measurement the conversion of the macromer to poly-macromer was shown to be high percentage, but the degree of polymerization of poly-macromer was much lower than that expected in the case of regular monomers such as styrene.     

含规整PMMA支链的共聚物及其离聚体的力学性能

研究了用聚甲基丙烯酸甲酯（ＰＭＭＡ）大单体与丙烯酸丁酯（ＢＡ）共聚制得的接枝共聚物及其与ＢＡ及丙烯酸（ＡＡ）共聚并中和制得的离聚体的力学性能与支链分子量、支链含量、共聚物分子量、羧基含量、中和度及离子种类的关系．结果表明这二种产物均呈现较好的热塑性弹性体行为，而离聚体的性能更为优越。     

Effect of methyl methacrylate content on coatings’ properties of palm oleic acid-based macromer

The macromer was synthesized using medium oil length oleic acid, phthalic anhydride, and glycerol. The synthesized macromer and methyl methacrylate (MMA) were copolymerized by free radical polymerization in toluene. The ratio between the macromer and MMA changed, and the effects on different properties of the copolymers, such as glass transition temperature (T _g) and film properties, were studied. The macromer and copolymer structures were characterized by FTIR and ¹H NMR spectroscopies. The coatings prepared with the highest ratio of MMA exhibited better overall physico-chemical properties. Alternatively, Tafel polarization curves showed that the corrosion rate value in NaCl solution decreases significantly when the MMA content is increased. Dynamic mechanical analysis results revealed that the increasing amounts of MMA lead to increasing T _g values of copolymers.     

核壳聚合物负载茂金属催化剂及乙烯聚合

采用半连续种子乳液聚合法,得到了粒径为280 nm左右的以聚甲基丙烯酸甲酯 (PMMA)为核、聚苯乙烯(PS)为壳的PMMA/ PS核壳结构聚合物和以PS为核、PMMA为壳的PS/PMMA核壳结构聚合物.并分别以上述二种核壳聚合物为载体,超临界CO2为溶剂,采用超临界流体浸渍法负载二氯二茂钛(Cp2TiCl2)催化剂,得到PMMA/PS-Cp2TiCl2和PS/PMMA-Cp2TiCl2两种负载型的茂金属催化剂颗粒.通过对二种催化剂颗粒的乙烯淤浆聚合动力学的研究发现,PMMA/PS-Cp2TiCl2催化剂颗粒的聚合反应速度有很大的滞后效应,聚合最大反应速率出现在第9 min,而PS/PMMA-Cp2TiCl2催化剂颗粒动力学行为与Cp2TiCl2催化剂均相聚合相似.     

PMMA-g-PS对CPE/PS共混体系性能的影响

采用大单体技术合成聚苯乙烯和甲基丙烯酸甲酯的规整接枝共聚物PMMA-g-PS。研究了共聚合反应条件聚苯乙烯大单体的投料质量分数、引发剂用量、反应温度对接枝效率的影响;研究PMMA-g-PS作为CPE/PS体系的共混增容剂时,共混物的组成、接枝物的用量、接枝物的组成对共混物物理机械性能的影响。用SEM,DSC表征共混物的变化,结果表明,接枝共聚物能促进两组分相容,起到增容剂的作用。     

聚苯乙烯大单体和丙烯酸辛酯的规整接枝共聚物

采用聚苯乙烯大单体和丙烯酸辛酯进行自由基溶液共聚合反应，得到规整接枝共聚物。产物通过萃取法提纯后，用IR表征其结构。研究了共聚合反应条件：聚苯乙烯大单体的投料质量分数，引发剂用量，反应温度对接枝效率的影响；并测定了丙烯酸辛酯在不同反应时间的竞聚率，接枝共聚物的稀溶液性质以及物理机械性能。结果表明，当聚苯乙烯大单体的投料质量分数在40％左右时，此接枝共聚物是一种性能良好的热塑性弹性体。     

Effect of the lateral substituent on the mesomorphic behavior of side-chain liquid-crystalline polymers containing a Schiff base ester

New polymerizable macromers containing a Schiff base ester linkage have been synthesized. These macromers were used to synthesize side-chain liquid-crystalline polymers (SCLCPs) by radical polymerization. The chemical structures of the macromers and polymers were characterized by spectroscopic techniques (FTIR, ¹H NMR, and ¹³C NMR). The mesomorphic properties of the macromers as well as the polymers were studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) and confirmed by powder X-ray diffraction (PXRD). POM and DSC studies revealed that all of the macromers and polymers showed liquid crystal behavior, with their nematic phases occurring in different mesophase ranges. The macromer without a lateral unit in the mesogen (M1) showed a thermal transition at a relatively high temperature (181.4 °C), whereas the macromer with a lateral unit in the mesogen (M2) showed a thermal transition at a relatively low temperature (101.8 °C). The SCLCP from macromer M1 (HPM1) also showed a comparatively high-temperature thermal transition compared to that of the polymer from macromer M2 (HPM2). The thermal properties of the polymers were studied by thermogravimetric analysis (TGA). The polymer from the macromer with a lateral unit in the mesogen (M2) showed higher thermal stability than the polymer from the macromer without a lateral unit (M1).     

Effect of talc/MMA in situ polymerization on mechanical properties of PVC‐matrix composites

In this study, polymethyl methacrylate (PMMA)‐coated talc was produced by the in situ polymerization of methyl methacrylate on the talc surface. The polymerization reaction was performed by both batch and semicontinuous emulsion processes. The polymerization kinetics, particle size and distribution, grafting efficiency, and coated‐talc morphology were systematically investigated. It was found that the talc particles have no effect on the polymerization of PMMA. The PMMA produced was found to cover the talc surface well. However, only a small amount can be grafted onto the talc. The size distribution of talc particles treated by semicontinuous emulsion polymerization is more uniform than by batch polymerization. The treated talc was subsequently used as filler in a poly(vinyl chloride) (PVC) matrix, and mechanical properties of the PMMA‐coated‐talc/PVC composites were studied. Morphological structure of PVC‐matrix composites revealed that the PMMA coating on talc improved the dispersion of talc in the PVC matrix and enhanced the interfacial adhesion between the talc and PVC. The mechanical properties of the composites, especially the impact strength, were found to be improved. There appears to be a critical covering thickness of PMMA on the talc surface for optimum toughening. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2105–2112, 2001     

Preparation of raspberry‐like poly(methyl methacrylate) particles by seeded dispersion polymerization

The facile preparation of nonspherical raspberry‐like poly(methyl methacrylate) (PMMA) particles by seeded dispersion polymerization of methyl methacrylate (MMA) on micron‐sized PMMA seed particles was described. Various polymerization parameters influencing the particle morphology, as well as the polymerization kinetic and morphological stability, were investigated in detail. It was found that the following polymerization conditions were necessary to prepare this kind of nonspherical particles: a relatively low temperature, an appropriate ratio of seed/MMA, an initiator with a relatively low decomposition rate, and a relatively low initiator concentration. These particles showed very good morphological stability at room temperature, but they changed to the spherical ones when heat treated at 60°C in methanol solution of MMA. The experimental results suggest that the prepared PMMA particles were kinetically favored and the localized polymerization of the MMA monomer on PMMA seed particle surface was responsible for the formation of the raspberry‐like particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011