聚有机硅氧烷的研究——Ⅳ.碱对聚二甲基硅氧烷交联的影响

高分子量的线型聚二甲基硅氧烷,即硅橡胶,可用八甲基环四硅氧烷(简称D_4)在适当催化剂下进行开环聚合。工业上普遍采用的聚合催化剂是氫氧化鉀。为了使催化剂能够均匀地分散在D_4中,可将氫氧化鉀和适量的D_4先行反应,形成合碱量較大的低分子量的聚二甲基硅氧烷(简称碱胶),然后以这种碱胶作为催化剂使D_4聚合。     

聚硅氧烷空心胶囊的制备及Heck偶联催化应用

研究了空心聚硅氧烷纳米胶囊负载的钯复合物的制备。合成了胶囊负载的腈钯复合物并研究了它们在烯烃芳基化Heck偶联反应中的催化性能。在O/W型聚二甲基硅氧烷微乳模板核上,共聚一定比例的4-(三乙氧基硅基)-丁腈和二甲基二甲氧基硅烷的有机硅单体,,然后用溶剂溶解透析的方法去除模板核聚二甲基硅氧烷而得到空心纳米胶囊.与醋酸钯反应后用KBH4还原得到空心聚硅氧烷胶囊负载的钯复合物。TEM,AFM等结果显示空心聚硅氧烷纳米胶囊负载的钯复合物已得到制备。该复合物对Heck反应具有很高的催化活性和立体选择性。     

端环氧基聚硅氧烷对环氧模塑料的改性

引入端环氧基聚硅氧烷对环氧封装材料的低应力化作用，将聚硅氧烷直接与环氧树脂及固化剂共混，由于聚硅氧烷不能完全键事到脂基体上，模塑料出现表面渗油，将端环氧基聚二甲基硅氧烷首先与不环氧树脂首先与环氧树脂的固化剂－酚醛树脂预反应形成嵌段共聚物，然后再与环氧树脂混合，解决了渗油，使聚硅氧烷在环氧树脂中的分布更均匀，相区尺寸更小，在环氧树脂固化物中，聚硅氧烷微区尺寸依赖于预反应条件、聚硅氧烷嵌段链长和聚硅氧     

聚苯乙烯-b-聚硅氧烷-b-聚苯乙烯三嵌段共聚物的合成及表征

采用乙烯基封端的聚 (二甲基硅氧烷 )与溴化氢反应制得末端含有C Br的双官能聚 (二甲基硅氧烷 ) ,以此聚 (二甲基硅氧烷 )大分子为引发剂 ,CuCl为催化剂 ,4 ,4′ 二 (5 壬基 ) 2 ,2′ 联吡啶为配体 ,通过原子转移自由基聚合法 ,制得分子量和结构可控的聚苯乙烯 b 聚硅氧烷 b 聚苯乙烯 (PSt b PDMS b PSt)共聚物 .     

八甲基环四硅氧烷阴离子乳液聚合反应的研究

研究了八甲基环四硅氧烷(D_4)在十二烷基本磺酸(DBSA)及其钠盐(Na-DBSA)作用下的阴离子乳液聚合反应,讨论了温度、乳化剂和催化剂用量对反应速度及聚合物分子量的影响。认为该聚合反应包括D_4的水解开环、D_4和羟基硅氧烷的加成及羟基硅氧烷之间的缩合三类基本反应,乳液颗粒表面是主要反应区。     

紫外光固化聚二甲基硅氧烷脲撑氨基甲酸甲基丙烯酸酯的研究——Ⅱ亲水疏水共聚网络体系

本文以α、ω-二氨丙基封端的聚二甲基硅氧烷、甲苯二异氰酸酯、甲基两烯酸羟乙酯为原料,合成了甲基丙烯酸酯封端的聚二甲基硅氧烷聚氨酯。并以此作为反应性低聚物,以甲基丙烯酸羟乙酯为亲水性反应稀释剂,通过紫外光固化,合成了一系列聚硅氧烷含量不同的共聚网络。应用红外光谱、凝胶含量测定、热分析、动态力学性能、吸水性实验等方法,对它们的固化程度、亲水疏水性能进行了研究。结果表明:体系中存在着两相结构,增加稀释剂的含量,材料的吸水性增加。通过调节疏水性的聚二甲基硅氧烷和亲水性的甲基丙烯酸羟乙酯的含量可改变体系的亲水疏水平衡。     

大环聚硅氧烷分子

聚硅氧烷是一种重要的高分子材料,其优良的物理化学性能使其在化工、冶金、建筑等众多领域具有广泛的应用,由于缺少链端基,环状聚硅氧烷这种特殊的空间结构使其具有尤为特定的性质和应用性能.本文主要简述了环状聚硅氧烷相比一般线形聚硅氧烷所具有的本体、溶液和化学特性.因为聚二甲基硅氧烷是硅氧烷中最主要的一种,所以本文主要对大环聚二甲基硅氧烷的合成方法和基本性质进行了综述,并介绍了大环聚硅氧烷的应用方向,主要是在拓扑嵌入、形成索烃和聚轮烷等方面的应用.     

含苯并氮杂15-冠-5侧基的线型聚硅氧烷促进液膜离子传输性能

N-十一碳烯和N-烯丙基苯并氮杂15-冠-5和甲基二氯硅烷硅氢加成后, 再与端羟基聚二甲基硅氧烷反应, 用三甲基氯硅烷封端, 合成了两种含苯并氮杂15-冠-5侧基的线型聚硅氧烷。分别以两种聚合物为液膜离子传输载体, 研究了载体种类、阴离子、阳离子种类及载体浓度和盐浓度对离子传输速率的影响, 并考察了膜的稳定性。     

氨基聚硅氧烷对改性环氧树脂的形态与性能的影响

将带有Ｎ－（β－氨乙基）－γ－氨丙基侧基的聚二甲基硅氧烷与环氧树脂共混,制备了聚硅氧烷改性环氧树脂固化物。研究了氨基聚硅氧烷的氨基含量对改性环氧树脂的形态和性能的影响。结果表明,改性环氧树脂固化物的形态与性能主要依赖于氨基聚硅氧烷的氨基含量,在环氧树脂中引入适宜氨基含量的氨基聚硅氧烷,可在一定程度上降低其模量,提高其柔性,并可明显改善环氧树脂的表面性能。     

六甲基环三硅氧烷非平衡聚合的研究

六甲基环三硅氧烷(D_3)在为催化剂,二甲亚砜为促进剂的情况下聚合,得到了分子量分布窄且没有大环体的聚二甲基硅氧烷。本文指出了反应溶液中溶解的氧会降低催化剂的活性。在除去了溶液中的氧以后,聚合反应速度大为加快,D_3转化率几乎达100％,而且得到的聚合物是活性高分子,可以继续进行聚合。同时还研究了在除氧以后D_3非平衡聚合反应的特点。     

硅氧烷乳液聚合的研究Ⅲ.八甲基环四硅氧烷在阳离子乳液聚合过程中乳液颗粒的形成

八甲基环四硅氧烷(D_4)在阳离子乳液聚合过程中,首先被乳化成颗粒较大的“过渡粒子”,在这里以D_4的水解开环和加聚反应为主,然后转变为颗粒较小的稳定乳液粒子。聚合物端基≡SiOH的缩合反应主要在乳液粒子中进行。     

硅氧烷乳液聚合的研究——Ⅰ.环硅氧烷在阳离子乳化剂存在下的乳化与聚合

<正> 有机硅乳液早已得到广泛应用,但关于有机硅乳液聚合以及反应机理的文献却很少。我们对此做了较为系统的研究,本文首先讨论了单体转化率的测定方法,探讨了乳液的形成过程,比较了不同的环硅氧烷向水相扩散及聚合的速度。     

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。     

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.     

杯芳烃交联聚硅氧烷热稳定性能研究

聚有机硅氧烷是一类主链由硅-氧键连接而成,侧链为有机基团的聚合物,兼具有机聚合物和无机聚合物的特性,性能优异,尤以卓越的耐高温性能而著称,在大气中于-50~250℃可以长期使用[1].为了进一步提高聚有机硅氧烷的热稳定性,主要有以下几种方法,(1)添加各种耐热性添加剂,或可与聚     

From monomeric to polymeric ferroelectric liquid crystals A comparative study of ferroelectric properties

Two new ferroelectric oligosiloxanes, a cyclic tetramer and a twin, have been synthesized. By a comparative study with their corresponding monomer and side chain polysiloxanes, the influence of oligo- and polymerization on the liquid crystalline and ferroelectric properties have been investigated. Polymerization leads to a stabilization of LC phases through increase of the clearing temperatures and suppression of crystallization. Oligomerization also leads to mesophase broadening, but, due to the low degree of polymerization, the effect is inferior to the linear polysiloxanes. The low viscosity of the oligosiloxanes ensures response times in the microsecond region, thus being comparable with their monomer and conventional LMWFLCs. It is found that polymerization increases the spontaneous polarization P_s. This is attributed to the density increase after polymerization, enhancing the inter-mesogenic interactions. The collective and local dynamics of the OFLCs are influenced differently with respect to their molecular structures. Each oligomer is already a good model for its corresponding polymer concerning the soft mode dynamics. For the local β-relaxation a similar temperature dependence of the relaxation times τ for the cyclic tetramer and for the side chain polysiloxanes is observed. The long axial rotation of the twin, having a very efficient decoupling, is significantly faster, thus resembling the monomer.     

From monomeric to polymeric ferroelectric liquid crystals A comparative study of ferroelectric properties

Abstract

Two new ferroelectric oligosiloxanes, a cyclic tetramer and a twin, have been synthesized. By a comparative study with their corresponding monomer and side chain polysiloxanes, the influence of oligo- and polymerization on the liquid crystalline and ferroelectric properties have been investigated. Polymerization leads to a stabilization of LC phases through increase of the clearing temperatures and suppression of crystallization. Oligomerization also leads to mesophase broadening, but, due to the low degree of polymerization, the effect is inferior to the linear polysiloxanes. The low viscosity of the oligosiloxanes ensures response times in the microsecond region, thus being comparable with their monomer and conventional LMWFLCs. It is found that polymerization increases the spontaneous polarization P _s. This is attributed to the density increase after polymerization, enhancing the inter-mesogenic interactions. The collective and local dynamics of the OFLCs are influenced differently with respect to their molecular structures. Each oligomer is already a good model for its corresponding polymer concerning the soft mode dynamics. For the local β-relaxation a similar temperature dependence of the relaxation times τ for the cyclic tetramer and for the side chain polysiloxanes is observed. The long axial rotation of the twin, having a very efficient decoupling, is significantly faster, thus resembling the monomer.     

聚硅氧烷聚丙烯酸酯改性聚氨酯三元复合乳液中偶联剂丙烯酸羟乙酯的作用

用异佛尔酮二异氰酸酯与仲羟基封端的聚硅氧烷( PMTS)反应在PMTS分子链端引入异氰酸酯基团,然后将其与聚丙二醇反应制得聚硅氧烷改性聚氨酯( PSU)预聚体,最后加入丙烯酸酯单体(AC)通过乳液聚合制备了非偶联型聚硅氧烷聚丙烯酸酯改性聚氨酯( PSU-AC)三元复合乳液.在PSU与AC聚合时加入丙烯酸羟乙酯(HEA)...     

Modification of epoxy-novolac resins with polysiloxane containing nitrile functional groups: synthesis and characterization

Synthesis of the statistical epoxidized polycyanopropylmethylsiloxane-co-polydimethylsiloxanes (PCPMS-co-PDMS) has been demonstrated. The modified polysiloxanes were prepared via a two-step method; (1) the ring-opening polymerization of octamethylcyclotetrasiloxane (D₄) and tetramethylcyclotetrasiloxane (D₄H), (2) hydrosilylation reaction of the polysiloxane prepolymers with allyl cyanide and allyl glycidyl ether. Molar ratios of D₄H and D₄ were varied to produce the modified polysiloxanes with differences in polarity. ¹H-NMR, ²⁹Si-NMR, ¹³C-NMR and FTIR were used to monitor the formation of the modified polysiloxanes and DSC was used to study their thermal behaviors (T_g, −118 to −68 °C). The use of the modified polysiloxanes as an elastomeric component in epoxy-novolac networks was also investigated. TEM and their transition temperatures suggested that the epoxy-novolac networks with high content of PDMS modifiers exhibited microphase separation. The fracture toughness properties of the networks with the polysiloxane modifiers were improved over the controls without polysiloxanes.     

Polymers and cyclic compounds based on a side‐opening type cage silsesquioxane

Polymers having polyhedral oligomeric silsesquioxane (POSS) in the main chains are an important class of organic–inorganic hybrid materials. Despite the increasing attention to the POSS polymers, variation of the monomers is still limited. Herein, we have proposed side‐opening POSS (SO‐POSS) monomers. Platinum‐catalyzed hydrosilylation polymerization proceeded to produce polysiloxanes having SO‐POSS in the main chains. The obtained polysiloxanes showed good solubility, high thermal stability, high transparency, and tunable reflective index. In addition, cyclic compounds were obtained during the investigation of the polymerization, and were synthesized with high selectivity under the slightly diluted conditions. The obtained cyclic compounds showed high thermal stability due to the silsesquioxane backbone, and the high dispersibility as a filler in poly(methyl methacrylate) was demonstrated. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2243–2250