甲基乙烯基硅氧烷环体的气质分析

对甲基乙烯基硅氧烷环体样品进行了气质分析研究。结果发现,除三甲基三乙烯基环三硅氧烷和四甲基四乙烯基环四硅氧烷这两个主要组分外,还共检测出3个杂质组分;经质图谱解析,这3个组分被确定为三甲基二乙烯基乙基环三硅氧烷、四甲基三乙烯基乙基环四硅氧烷和五甲基三乙烯基环四硅氧烷。     

四甲基二乙烯基二硅氧烷脱水剂的选择

研究了四甲基二乙烯基二硅氧烷(VM)中的水分含量对乙烯基硅油产品质量的影响,比较了氯化钙(CaCl2)、3分子筛、4分子筛、5分子筛四种脱水剂对VM的脱水效果。结果表明,VM中的水分对乙烯基硅油的黏度及挥发分含量有显著影响;四种脱水剂中,4分子筛的脱水效果最好,不仅可以有效降低四甲基二乙烯基二硅氧烷中的水分含量,而且小幅提高了其纯度。     

MQ硅树脂的热稳定性研究

分别将六甲基二硅氧烷、二乙烯基四甲基二硅氧烷、二氢四甲基二硅氧烷与正硅酸酯进行共水解缩聚反应,合成出甲基MQ硅树脂、乙烯基MQ硅树脂和含氢MQ硅树脂。利用热失重分析对3种MQ硅树脂在氮气气氛下的热降解行为和空气气氛下的热氧化降解行为进行了研究,结果表明,在氮气和空气气氛下,乙烯基MQ硅树脂的热稳定性均最优,甲基MQ硅树脂次之,而含氢MQ硅树脂最差。     

高撕裂强度加成型医用液体硅橡胶的研制

以八甲环四硅氧烷(D_4)或二甲基环硅氧烷混合物(DMC)及四甲基四乙烯环四硅氧烷为原料、1,1,3,3-四甲基-1,3-二乙烯基硅氧烷或六甲基二硅氧烷为封端剂,经催化聚合制得不同乙烯基含量的乙烯基硅油;以酸催化合成了含氢硅油;以白炭黑为填料,六甲基二硅氮烷、四甲基二乙烯基二硅氮烷等为结构控制剂来进行密炼等工序制备实验所需要的基胶;以多乙烯基硅油为集中交联剂,制备了高撕裂强度的医用透明液体硅橡胶。探讨了白炭黑比表面积及用量、多乙烯基硅油的用量、四甲基二乙烯基二硅氮烷的添加量对液体硅橡胶撕裂强度的影响。结果表明,要制备高撕裂强度的医用液体硅橡胶,必须添加一定量的多乙烯基硅油,并且四甲基二乙烯基二硅氮烷的添加对促进撕裂强度的增长有很大的作用。当乙烯基硅油100份、比表面积为250 m~2的白炭黑29份、多乙烯基硅油4份、四甲基二乙烯基二硅氮烷用量为白炭黑质量的3%所制得的液体硅橡胶,其撕裂强度能达51 k N/m、邵尔A硬度61度、拉伸强度9.2 MPa、拉断伸长率500%。     

膜用高乙烯基含量硅橡胶的合成与表征

以八甲基环四硅氧烷(D4)和四甲基四乙烯基环四硅氧烷(Dvi4)为单体、四甲基二乙烯基二硅氧烷(Mmvi)为封端剂、氢氧化钾为催化剂,合成了乙烯基摩尔分数为5%的硅橡胶PVDMS.研究了反应时间、反应温度及Mmvi加入量对产物黏度的影响,得到的最佳合成条件为反应温度140℃、反应时间180～210 min、MMvi质量分数0.9%～1.8%.用傅里叶变换红外光谱和核磁共振氢谱对其结构进行了表征,并计算了产物中的乙烯基含量,得到的结果与预期值相一致.将产物与国外牌号为184和VP7660的产品进行了膜性能比较,结果表明所得PVDMS性能良好,可替代进口硅橡胶产品.     

铂催化加成型液体乙烯基硅橡胶性能

制备了两种铂催化剂：氯铂酸-二乙烯基四甲基二硅氧烷和氯铂酸-异丙醇,比较了其在加成型液体乙烯基硅橡胶的制备中的催化作用,并着重分析了氯铂酸-二乙烯基四甲基二硅氧烷（Karstedt型）催化荆加入量对硅橡胶性能的影响。结果表明,氯铂酸-二乙烯基四甲基二硅氧烷的活性比氯铂酸-异丙醇的活性大;在一定范围内,随着催化剂用量增加,硅橡胶硫化时间缩短,介电常数和介电损耗增加;当氯铂酸-二乙烯基四甲基二硅氧烷催化剂质量分数为1．15×10^-5时,硅橡胶固化良好,介电常数和介电损耗较小且随频率变化较稳定。     

加成型双组分苯基硅树脂在功率型LED中的应用

以苯基三甲氧基硅烷、二苯基二甲氧基硅、二甲基二乙氧基硅烷、二乙烯基四甲基二硅氧烷、二氢基四甲基二硅氧烷、六甲基二硅氧烷等为原料,制备了高折射率加成型双组分甲基苯基乙烯基硅树脂;并将其用于功率型（1～3 W）发光二极管（LED）5050的封装,然后进行常温点亮试验、高温点亮试验、回流焊试验、-40～100℃冷热冲击试验和墨水渗透试验。结果表明,各项指标均合格,其性能可与国外同类产品相近。     

双端乙烯基氟硅油的研制

以1,3,5-三甲基-1,3,5-三(3,3,3-三氟丙基)环三硅氧烷为原料、四甲基二乙烯基二硅氧烷为封端剂、硫酸为催化剂制得双端乙烯基氟硅油,研究了反应时间、催化剂用量、反应温度对产物黏度和挥发分质量分数的影响;采用红外光谱和核磁共振波谱表征了产物结构.结果表明,产物为双端乙烯基氟硅油.较佳的制备条件为反应时间1 h...     

低黏度自交联氟氢乙烯基硅油的合成及应用

采用阳离子交换树脂催化八甲基环四硅氧烷(D4)、四甲基四氢环四硅氧烷(D4H)和三氟丙基三甲基环三硅氧烷(D3F)开环共聚,以四甲基二乙烯基二硅氧烷(D2Vi)为封端剂,制备了低黏度自交联氟氢乙烯基硅油(F-PMHS).探讨了聚合温度、聚合时间、催化剂用量、催化剂循环等因素对聚合反应的影响.通过FTIR、1HNMR、TGA对共聚物进行分析.结果表明,当聚合温度为60℃、反应时间为6 h、催化剂用量为总单体质量5％时,得到的F-PMHS产率为88.69％,黏度为32.7 mPa·s.将硅油进行涂膜测试,所得涂膜固化性好,剥离力低至7 g/25 mm,水滴静态接触角达114.9°.     

发泡硅橡胶的制备及应用性能研究

以D_4(八甲基环四硅氧烷)、D_4~(Vi)(四甲基四乙烯基环四硅氧烷)和D_2~(Vi)(四甲基二乙烯基二硅氧烷)为原料,THMA(四甲基氢氧化铵)为催化剂,制备得到生胶,通过添加其他组分得到发泡硅橡胶。研究结果表明:合成甲基乙烯基生胶的反应温度应为110℃,反应时间应为5 h;以100 g甲基乙烯基生胶为基胶,当补强剂、发泡剂、硫化剂、结构化控制剂以及发泡助剂的用量分别为40份、8份、2.5份、5份、0.2～0.3份时制得的发泡硅橡胶孔致密均匀,发泡倍率大,力学性能最佳。     

Synthesis of surface-active quaternary amino polyfluorosiloxanes

We report synthesis of surface-active quaternary amino polyfluorosiloxanes. Hydrosilation of silanic hydrogen containing polyfluorosiloxanes with olefinic epoxides, in the presence of a platinum–divinyltetramethyldisiloxane complex gave epoxy polyfluorosiloxanes. These, on further reaction with various amines followed by quaternization, gave quaternary amino polyfluorosiloxanes. The quaternary amino polyfluorosiloxanes reduce surface tension of water to 25 mN/m² at a 25-millimolar concentration. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1700–1708, 2000     

New routes to phenylsilicones

Two alternative nonhalogen routes for the synthesis of phenylsilanes have been explored. In the first method, 2,3-dimethylbutadiene is reacted with divinyltetramethyldisiloxane via a Diels–Alder reaction. The product can then be aromatized. In the second method, cyclohexadiene undergoes hydrosilylation and the resultant product can be aromatized using palladium on carbon with nitrobenzene as an electron accepter. Phenylsilicones can be prepared in a single step in which a silicone hydride fluid and cyclohexadiene are refluxed in the presence of Pt/C (platinum on carbon) and nitrobenzene. © 1994 John Wiley & Sons, Inc.     

Mechanistic studies of platinum-catalyzed hydrosilylation

The results of competitive and relative rate studies for various silicon hydrides and vinylmethylsiloxane compounds are presented. For example, the competitive reaction of bis(trimethylsiloxy)methylsilane with vinylpentamethyldisiloxane (A) and divinyltetramethyldisiloxane (B) show that B reacts preferentially; however, the relative rate of reaction is greater for A than B. Mechanistic aspects of hydrosilylation are also discussed.This paper is from the Second International Topical Workshop, Advances in Silicon-Based Polymer Science.     

Preparation of MT-type polysiloxane containing active vinyl groups with low hydroxyl group content

MT-type polysiloxanes containing active vinyl group were prepared under acid conditions initiated from divinyltetramethyldisiloxane and methyltrimethoxysilane by one-pot method, co-hydrolysis method, and reaction-rectification coupling method, respectively. The influence of different methods on molecular weight, molecular weight distribution, and ratios of each kind of segment in the MT-type polysiloxane containing active vinyl group were discussed in detail. The results indicated that with the reaction-rectification coupling method, the residual hydroxyl segment in the prepared MT-type polysiloxane could be lower than 0.5 wt%. For MT-type polysiloxanes with high hydroxyl group content, the hydroxyl content could be reduced when treated with hexamethyldisilazane, trimethylchlorosilane, zinc naphthalate, or tetramethylammonium hydroxide under suitable conditions. Hexamethyldisilazane was the most convenient and effective regents among these four compounds, the residual hydroxyl content contained in the prepared MT-type polysiloxanes could be reduced from 13.4 to 0.9 wt% when MT-type polysiloxane sample was treated with hexamethyldisilazane.     

有机硅压敏胶用VMDQ型硅树脂的制备与性能

以四甲基二乙烯基二硅氧烷、二甲基二甲氧基硅烷和四甲氧基硅烷为反应原料,氢氧化钾(KOH)为催化剂,采用碱催化水解共聚法制备VMDQ型硅树脂,并采用FT-IR(红外光谱)法、1H-NMR(核磁共振氢谱)法和29Si-NMR(核磁共振硅谱)法证实了产物的结构与目标分子结构相吻合;然后以VMDQ型硅树脂作为基体树脂,制备相应的SPSA(有机硅压敏胶)。研究结果表明:采用单因素试验法优选出制备SPSA的最佳工艺条件是n(硅树脂中乙烯基)∶n(硅树脂)=0.003 2∶100、M/Q值为0.7和n(含氢硅油中SiH)∶n(硅树脂中SiCH=CH2)=0.4∶1,此时SPSA的持粘力为26 526 s、180°剥离强度为0.58 kN/m且拉伸剪切强度为14.5 MPa。     

Acyclic diene metathesis (ADMET) oligomerization of divinyltetramethyldisiloxane in the presence of rhodium and ruthenium complexes

Acyclic diene metathesis (ADMET) polymerization of divinyltetramethyldisiloxane in the presence of rhodium [RhCl(COD)]₂ and ruthenium RuCl₂(PPh₃)₃ catalysts led predominantly to linear oligomers [M _n=1815,M _w/M _n=1.16] if the rhodium catalyst was used or to mixtures of dimeric and trimeric oligomers if the ruthenium complex was applied. The rhodium complex appeared to be the first effective catalyst for ADMET polymerization of divinyldisubstituted organosilicon compounds.Part 14 in the series Metathesis of Silicon-Containing Olefins: for Part 13, see Ref. 8.     

Ruthenium catalyzed regioselective copolymerization of acetophenone and α,ω-dienes

Summary This paper reports a novel ruthenium catalyzed regioselective copolymerization reaction between acetophenone and ,-dienes such as divinyltetramethyldisiloxane and divinyldimethylsilane which leads respectively to copoly(3,3,5,5-tetramethyl-4-oxa-3,5-disila-1,7-heptanylene/2-acetyl-1,3-phenylene) and copoly(3,3-dimethyl-3-sila-1,5-pentanylene/2-acetyl-1,3-phenylene). This reaction involves the ruthenium catalyzed insertion of the carbon-carbon double bonds of ,-dienes into the aromatic C–H bondsortho to the acetyl group of acetophenone. Similar ruthenium catalyzed reactions between acetophenone and alkenes to yield monomericortho alkyl substituted acetophenones have been recently reported.¹     

Novel fluorescence method for cure monitoring of hydrosilation‐curable silicones

This study aimed to evaluate a reactive fluorescent probe, 9,10‐bis‐(phenylethynyl) anthracene (BPEA), for cure monitoring of hydrosilation‐curable silicones. The hydrosilation‐curable silicones consisted of a vinyl‐terminated polydimethylsiloxane prepolymer, a methylhydrosiloxane‐dimethylsiloxane copolymer, and an inhibitor, 1,3‐divinyltetramethyldisiloxane. The hydrosilation reaction was catalyzed with the solution of a platinum catalyst in the prepolymer. The catalyst solution also contained a trace amount of the reactive fluorescent probe. Three hydrosilation‐curable silicones, with the prepolymer of varying molar mass, were investigated. Each of the hydrosilation‐curable silicones was mixed with the catalyst solution at the mass ratio of 1 : 1 to initiate the cure. During the cure of each mixture at 22°C, the elastic modulus of the mixture and the fluorescence spectrum of the probe at the excitation wavelength of 360 nm were measured. Initially, the elastic modulus changed slowly, but then increased rapidly as a result of the increase in molar mass. The elastic modulus leveled off and reached a plateau value at the setting time. The ratio of the fluorescence intensities at 422 and 466 nm increased steadily, and then leveled off and reached a plateau value at the setting time, in agreement with the setting time determined from the change in elastic modulus. The reactive fluorescent probe, BPEA, can therefore be used for nondestructive fluorescence monitoring of hydrosilation‐curable silicones. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009