紫外光固化超支化聚硅氧烷的合成及其光固化动力学研究

利用γ-甲基丙烯酰氧基丙基三甲基硅氧烷的受控水解反应即A2-B3单体对法来制备超支化聚硅氧烷,并对合成出的聚合物通过FT-IR、1H-NMR和多角度激光光散射技术(MALLS)进行了表征.结果表明,所得聚合物具有超支化结构且分子中含有大量活性官能团,从而可以实现紫外光引发固化.通过等温差示光量热实验(DPC)研究了聚合物结构、引发剂用量、光强度和聚合温度对聚合物光固化行为的影响规律,并得到了其中一种聚合物的光固化动力学参数,光固化反应总级数约为3,表观活化能为16.9kJ/mol.     

超支化聚硅氧烷的紫外光固化行为及固化动力学研究

采用等温差示光量热技术(DPC)研究了超支化聚硅氧烷的紫外光固化行为及固化动力学. 探索了引发剂浓度、 光强度、 聚合温度和环境气氛对固化行为的影响规律. 研究结果表明, 增加光引发剂浓度和光强度及提高环境温度均可提高其固化速率和双键最终转化率. 在空气中固化时存在氧阻聚现象, 增大光强度可以显著缩短诱导期. 运用带扩散因子的自催化固化动力学模型研究了其光固化动力学, 计算出特定条件下的光固化动力学参数, 反应总级数约为6—7, 表观活化能为9.95 kJ/mol. 通过超支化聚合物与两种结构类似的低官能度单体光固化行为的对比, 研究了超支化聚合物固化行为与其分子结构的关系, 发现由于超支化大分子的独特结构, 在固化初始阶段便产生凝胶, 因此双键的最终转化率偏低.     

可光固化超支化聚硅氧基硅烷的合成与表征

自20世纪80年代末期Kim和Webster首次采用AB2型单体合成超支化聚合物以来，超支化聚合物以其新颖的结构、独特的性能和广泛的应用前景受到了科学界和工业界的广泛关注．其中超支化有机硅聚合物，尤其是硅氧基聚合物，由于具有良好的高低温稳定性、耐腐蚀性、耐候性等，以及硅氯、硅氢等末端基团易于功能化改性的特点，使其在功能性涂层材料、催化剂以及液晶材料等领域具有重要的应用价值．到目前为止，有关超支化聚硅氧基硅烷的研究主要集中在AB2型单体（x≥2，A和B分别为硅氢基团和乙烯基、烯丙基等不饱和基团）的制备以及硅氢加成产物的功能化改性方面．     

特定乙烯基和硅氢键含量聚硅氧烷的可控制备

以1,3,5-三乙烯基-1,3,5-三甲基环三硅氧烷与六甲基环三硅氧烷为共聚单体,四氢呋喃为溶剂,在正丁基锂引发条件下实现可控阴离子开环共聚,制备特定乙烯基含量的聚硅氧烷;同时,以1,3,5,7-四甲基环四硅氧烷与六甲基环三硅氧烷为共聚单体,四氢呋喃为溶剂,在浓硫酸引发条件下实现可控阳离子开环共聚,制备特定硅氢键含量的聚硅氧烷,为制备具有特定乙烯基和硅氢键含量聚硅氧烷国防专用标准物质奠定了基础。     

超支化烯丙基聚硅氮烷-巯基化合物体系紫外光固化研究

采用等温差示光量热扫描技术(DPC)研究了超支化烯丙基聚硅氮烷-巯基化合物体系的紫外光固化.对比了超支化聚合物-巯基化合物体系、二官能烯丙基硅氮烷-巯基化合物体系和超支化自聚体系的紫外光固化特性,结果表明超支化-巯基化合物体系可在引发剂浓度低(0.1wt%)、辐照强度低(5mW/cm2)的情况下迅速发生光固化反应;与超支化自聚反应相比固化速率高、双键转化率高;而与低官能-巯基化合物体系相比,由于超支化分子结构的独特性,导致固化速率快,双键转化率偏低.对引发剂浓度、辐照强度和反应温度对固化行为的影响表明,在引发剂浓度不超过0.5wt%和辐照强度不大于30.50mW/cm2时,反应速率分别与引发剂浓度和辐照强度的1/2次方成线性关系.运用带扩散因子的自催化固化动力学模型研究了不同温度下的固化行为,计算出特定条件下的光固化动力学参数,表观总反应级数约为8.76,表观活化能为13.97kJ/mol.     

超支化聚硅氧基硅烷的合成及其表征

基于线性聚硅氧烷在国防、能源和化工等领域的广泛应用,具有新颖拓扑结构和大量功能性端基的超支化聚硅氧烷引起了国内外科学工作者的广泛兴趣[1~7].到目前为止,主要是采用水解缩聚的方法合成超支化单体,在铂系催化剂存在下进行硅氢加成反应或者在碱催化剂存在下进行质子转移聚合制备超支化聚合物[8~12].然而,以上合成超支化聚硅氧烷的方法仍然存在一定的不足.例如,水解法步骤繁琐,通常在第一步反应结束后需要多次除水,并继续滴加单氯硅烷以得到完全取代的大单体;同时多官能度单体容易水解自缩聚,产生A2B4或A3B6等副产物,不仅不利于结构控…     

直接合成三烷氧基硅烷铜系催化剂的研究现状

三烷氧基硅烷(HSi(OR)3)既含有可水解的Si-OR键,又具有活泼的Si-H键.其中,Si-OR键通过水解缩合可转化成聚硅氧烷,与格氏试剂反应可生成烷氧基硅烷;Si-H键在铂系催化剂作用下,可与一系列含不饱和基的化合物发生氢硅化加成反应,得到各种碳官能硅烷、硅氧烷及硅基改性有机聚合物[1     

《高分子化学》课程中结合超支化聚硅氧烷的案例教学研究

超支化聚硅氧烷作为一种新型的超支化聚合物,兼具了超支化聚合物和硅氧聚合物的优点,是《高分子化学》课程教学中具有典型代表性的前沿教学案例.本文以超支化聚硅氧烷为案例教学对象,从单体选择、原料配比、聚合过程控制等方面进行讨论,重点讲授逐步聚合、缩聚反应、凝胶点的预测等相关知识点;在此基础上进一步延伸到高分子材料结构与性能的...     

新型双功能性超支化聚合物的制备及表征

首先以烯丙基缩水甘油醚与N-氨乙基哌嗪反应合成新型B3单体,然后分别以六亚甲基二异氰酸酯和1,6-己二硫醇为A2单体与上述B3单体反应,利用异氰酸-羟基以及巯基-烯的反应,合成了同时含有羟基和烯丙基的双功能性超支化聚(氨酯-胺)和聚(硫醚-胺)。研究了单体种类及投料比与合成的超支化聚合物的化学与拓扑结构的关系。通过红外吸收光谱、核磁共振氢谱和凝胶渗透色谱表征了超支化聚合物的分子结构和化学组成。结果表明:该B3单体同时带有3个羟基与3个烯丙基,当A2和B3单体投料比(物质的量之比)为0.825∶1时,可以成功制备较高分子量的双功能性超支化聚合物。     

含环三硅氮烷的星形聚硅氧烷的合成——环硅氮阴离子引发环硅氧烷开环聚合

以环三硅氮锂盐（ＤＮＬｉ３）为引发剂，成功地引发了环硅氧烷开环聚合．通过含氮量测定，利用１Ｈ、２９ＳｉＮＭＲ和ＩＲ谱以及分子量测定（ＧＰＣ）和特性粘度测试，并与模型化合物进行比较，证明所得聚合物是含环三硅氮烷的星形聚硅氧烷．研究了六甲基环三硅氮锂盐引发八甲基环四硅氧烷（Ｄ４）开环聚合的动力学，结果表明该聚合反应相对于Ｄ４为一级反应，同时也比较了不同促进剂对聚合速率的影响，ＤＭＦ对聚合速率的促进作用比ｄｉｇｌｙｍｅ大     

Synthesis and characterization of ultraviolet‐curable hyperbranched poly(siloxysilane)s

Two UV‐curable hyperbranched poly(siloxysilane)s ( I and III ) containing vinyl and allyl end groups were synthesized via polyhydrosilylation with methylbis(methylethylvinylsiloxy)silane and methylbis(dimethylallylsiloxy)silane monomers. A cationic UV‐curable hyperbranched polymer ( II‐Ep ) with epoxy end groups was prepared via the hydrosilylation of hyperbranched polymer II with Si? H terminated groups and glycidyl methacrylate, and II was also obtained via the polyhydrosilylation of AB₂‐type monomer methylvinylbis(methylethylsiloxy)silane. All hydrosilylation reactions were catalyzed by Pt/C or chloroplatinic acid. Three AB₂‐type monomers were synthesized via the hydrolysis of functional chlorosilane, which was prepared with Grignard reagents and dichlorosilane. The molecular structures of the polymers were characterized with ¹H NMR, Fourier transform infrared, and gel permeation chromatography, and the UV‐curing behaviors of the polymers under different atmospheres and with different photoaccelerators were also investigated. The thermostability of uncured and cured polymers was examined with thermogravimetric analysis, and the data indicated that the orders of the onset decomposition temperatures for the cured polymers and the residue weights were as follows: III (380 °C) > I (320 °C) > II‐Ep (280 °C) and I (70.4%) > III (64.1%) > II‐Ep (60.9%), respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1883–1894, 2005     

Hyperbranched Polyurethane Acrylate Applied to UV Curable Flame Retardant Coatings

UV curable hyperbranched prepolymers based on amine-ester, ester-amide and ether-amide started with AB_2-type monomers have been prepared by the authors. A series of work on allyl ether maleate hyperbranched polyesters for UV curing coatings by Hult and his colleagues has been reported. However, the UV cured films from those materials are all flammable when attached to fire without addition of flame retardants. In this work, a new kind of hyperbranched polyurethane acrylate containing phosphorus     

光/潮气双重固化聚氨酯涂层的制备及性能研究

以甲苯-2,4-二异氰酸酯(TDI)和二乙醇胺(DEOA)为原料一步法合成了超支化聚氨酯,对其改性制备了光固化超支化聚氨酯丙烯酸酯(HPUA)和一系列双重固化(UV/潮气)超支化聚氨酯丙烯酸酯(DHPUA),使用傅立叶红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)和碳谱(13C-NMR)以及凝胶色谱(GPC)对其分子结构进行了表征.并以其为预聚物制备光固化涂层,通过对双重固化涂层的表面形貌、热性能和物理性能的研究,结果表明,超支化双重固化涂层经过潮气固化后,涂层表面的粗糙度随着树脂中硅氧烷端基的含量的增加先下降后上升;超支化双重固化涂层的物理性能和热稳定性都随着树脂中硅氧烷端基的含量的增加而提升.     

超支化聚碳硅氮烷的合成与表征

聚碳硅氮烷是一种新型含硅有机金属聚合物,其主链由硅氮碳连接而成,侧链为有机基团;与其它含硅聚合物(聚硅氮烷、聚碳硅烷等)类似,聚碳硅氮烷适于用做力学性能极佳且耐高温氧化的氮化硅(Si3N4)和氮化硅/碳化硅(Si3N4/SiC)复相陶瓷的前驱体.[1]超支化聚合物具有溶解性好、粘度低     

含有联苯和肉桂酸酯基团的侧链液晶共聚物的合成与表征

合成了两种含有联苯刚性基元的甲基丙烯酸酯单体M1和M2,其中M1为含有可光交联的肉桂酸酯端基的单体.通过溶液自由基聚合,得到一系列含不同比例M1和M2单体单元的聚丙烯酸酯类侧链液晶共聚物.采用1H-NMR、FT-IR等方法对单体和聚合物的结构进行了详细表征.用示差扫描量热法、偏光显微镜以及广角和小角X-射线衍射对单体和聚合物的液晶性进行了研究.结果表明,末端为肉桂酸酯基团的单体M1无液晶性,其均聚物P1有微弱的液晶性,而端基为正丁基的单体M2及其均聚物P9则表现出近晶相液晶行为.共聚物P2~P5均为向列型液晶,P6~P9则为近晶型液晶.随在聚合物中M2单体含量的增加,共聚物的玻璃化转变温度、熔点及清亮点温度均呈现增加趋势.     

Synthesis and Characterization of PEG Polymer Brushes via Cyclopolymerization of 1,2,3-Triazole Tethered Diacrylates

Poly(ethylene glycol) (PEG) macromolecular brushes were synthesized directly via re-versible addition-fragmentation chain transfer polymerization cyclopolymerization of diacry-late monomers bearing PEG functional groups through the formation of 11-member rings. The diacrylate monomers bearing PEG functional groups are the 1,2,3-triazole-tethered di-acrylate macromolecular monomers with different PEG lengths synthesized via the so-called “click” chemistry. The bulky hindrance of PEG chains affected the polymerization behavior of the diacrylate macromolecular monomers, and the diacrylate monomers showed strong tendency to cyclopolymerization rather than crosslinking. NMR analysis and gel perme-ation chromatography profiles proved the high e ciency of cyclopolymerization without sidereactions. The aqueous solutions of the obtained PEG macromolecular brushes were fluores-cent under UV excitation. The uorescence depended dramatically on the concentration of brush-like polymers due to the aggregation of cyclopolymer in water, and could be quenched by the addition of DNA.     

Ring-opening metathesis polymerization of cis-5-norbornene-endo-2,3-dicarboxylic anhydride derivatives using the grubbs third generation catalyst

A series of cis-5-norbornene-endo-2,3-dicarboxylic anhydride(NDCA,M1) derivatives(M2-M4) with different types of nonpolar substituted groups were synthesized and characterized by ~1H/~(13)C-NMR and mass spectrometry(MS). Ringopening metathesis polymerization(ROMP) of these monomers using the Grubbs third generation catalyst(G3) generated high molecular weight polymers with much improved solubility compared with the NDCA's homopolymer. It was found that the solubility of these polymers increased with increased substituent's steric hindrance. The living polymerization of NDCA derivative containing the bulkiest substituent(M4) catalyzed by G3 in tetrahydrofuran was confirmed by the kinetic studies with low polydispersity indices(PDI)( 1.30). By using sequential ROMP, well-defined diblock copolymers containing anhydride groups were synthesized.     

SYNTHESIS AND CHARACTERIZATION OF NEWLY DESIGNED POLY[DI(ALKYL) VINYLTEREPHTHALATE]S

A series of newly designed monomers of 2-vinylterephthalates (VT) were synthesized. The monomers contain onephenylene group connected with two alkyl groups (carbon number varying from 1 to 6) via ester linkage. Their chemicalstructures were confirmed by mass spectroscopy (MS), ~1-H-NMR, and elemental analysis (EA). The corresponding polymers,poly[di(alkyl) vinylterephthalate]s (PDAVTs), were obtained using convenional free redical polymerization. The polymerswere found to be able to develop inio liquid crystalline phase when the size of the alkyl group in the side-chain increases tobe larger than the ethyl group.