三元巯基/乙烯基硅氮烷UV固化制备聚合物陶瓷前驱体

采用差光量热扫描研究了三元巯基化合物与乙烯基硅氮烷紫外光固化特性,结果表明,随着光引发剂浓度和辐照强度的增加,体系聚合速率增大,体系终止方式以自由基双基偶合终止为主。聚合反应为一级,且聚合速率与乙烯基浓度有关,而与巯基浓度无关。对制备的聚合物陶瓷前驱体的基本性能进行分析表明,玻璃化转变温度随巯基化合物用量的减少而降低,在巯基-乙烯基硅氮烷等摩尔比时,体系的固化度最大。     

聚合物先驱体的结构对氮化硅陶瓷性能的影响

以紫外光固化巯基/乙烯基硅氮烷共聚体系制备了不同结构的聚合物陶瓷先驱体,高温裂解后得到氮化硅陶瓷,用X射线衍射仪,场发射扫描电镜和能谱仪等手段对巯基官能度、巯基化合物分子尺寸、巯基/乙烯基硅氮烷配比以及惰性填料进行了表征,研究了聚合物先驱体的结构对氮化硅陶瓷的结晶度和晶粒尺寸的影响,结果表明:巯基单体官能度和分子尺寸的增加导致先驱体陶瓷的结晶度提高以及平均晶粒尺寸降低;巯基单体相对含量的增加导致先驱体陶瓷的结晶度增加,乙烯基与巯基摩尔比为1:0.5时平均晶粒尺寸出现峰值;β-Si3N4粉体惰性填料的加入能明显抑制先驱体陶瓷的尺寸收缩.     

巯基-乙烯基点击反应在紫外光固化过程中的应用

巯基-乙烯基反应是点击化学中的一类重要反应,在紫外光固化过程中通过添加巯基化合物可以克服自由基聚合过程中的氧阻聚、光引发剂小分子碎片等,因而近年来在紫外光固化过程中引入巯基-乙烯基点击反应成为紫外固化材料领域的前沿研究内容。文中综述了近年来巯基-乙烯基点击反应在紫外光固化过程中的研究成果,详细介绍了巯基-乙烯基反应在紫外光固化过程中的优缺点、反应机理、分子选择及分子设计原理,最后对巯基-乙烯基反应在紫外光固化过程中的进一步应用前景做了展望。     

以硅铝氧烷溶胶为种子的VAc无皂乳液聚合研究EI

研究了以硅铝氧烷溶胶为种子进行醋酸乙烯酯 (VAc)的无皂乳液聚合 ,聚合动力学研究结果表明 ,VAc的聚合速率随无皂乳液聚合体系的稳定性而提高 ,IR测试结果表明硅铝氧烷溶胶中的双键参与了共聚反应 ,扫描电子显微镜 (SEM)照片表明有机和无机物得以较好的复合。 DSC结果表明 ,硅铝氧烷溶胶的浓度对     

含乙烯基的聚硅氮烷先驱体纤维的制备

通过甲基乙烯基硅氮烷与聚硅氮烷共热聚反应,将乙烯基引入先驱体聚硅氦烷,分析了甲基乙烯基硅氦烷与降硅氮烷的结构。讨论了两者共热聚的反应过程,找到了适宜的制备方法。制得了几种不同乙烯基含量的聚硅氦烷,并经熔融纺丝制得的含乙烯基的聚硅氦烷纤维。     

巯基化合物的合成及巯基-乙烯基光固化工艺

合成出三种不同官能度的巯基化合物,在对其表征的基础上,利用傅立叶变换红外光谱原位跟踪和紫外光差示扫描量热实时跟踪方法,研究了巯基化合物官能度、巯基与乙烯基配比和辐照强度对巯基-VL20体系光固化反应的影响规律。结果表明:高官能度的巯基化合物,反应速率较快;光聚合反应速率约与光强的0.5次方成正比。     

含活性基有机硅氮烷的合成及紫外光固化与热裂解研究

通过甲基乙烯基二氯硅烷及甲基氢二氯硅烷氨解并以NH4C l催化制备了四种含活性基团的有机硅氮烷。对其紫外光(UV)固化性能、机理及热裂解行为进行了研究。结果表明,紫外光可以有效地引发含活性基的有机硅氮烷固化,固化时主要发生N-H、-CH=CH2间的反应;增大低聚物中S i-H含量和硅氮烷的分子量,均可提高其裂解后的陶瓷产率。     

光聚合陶瓷先驱体裂解制备陶瓷涂层及其抗氧化性能

炭材应用广泛,但在高于500℃的有氧气氛中氧化迅速,其结构和性能受到严重影响.为此,采用光聚合巯基/乙烯基聚硅氮烷(PSN-1)陶瓷先驱体在炭材料表面裂解制备抗氧化陶瓷涂层,采用偏光显微镜和X射线衍射技术探讨了涂层对炭材抗氧化性能的影响.结果表明:先驱体溶液浓度为30%时浸渍效果最好;加入质量比(Ti/PSN-1)为1/10～1/5的钛粉时,制备的涂层抗氧化性能最佳,恒温氧化120 min后,失重率仅为18%;最佳的浸渍/裂解循环次数为3次,恒温氧化120 min,失重率为15%;聚硅氮烷经高温裂解后最终生成氮化硅陶瓷.     

含乙烯基的聚碳硅烷的合成

利用聚碳硅烷与甲基乙烯基硅氮烷共混热聚反应 ,制得了含乙烯基的聚碳硅烷。分析了甲基乙烯基硅氮烷的结构 ,讨论了两者共热聚的反应过程 ,研究了制备条件对产物性能的影响。通过熔融纺丝制得了含不同乙烯基的适于电子束辐照的聚碳硅烷纤维。     

不同分子量的陶瓷前驱体聚硅氮烷的结构与性能的研究

以甲基氢二氯硅烷、甲基乙烯基二氯硅烷为原料,采用氨解反应以及热聚合反应合成了一系列乙烯基氢基甲基聚硅氮烷(PSZ135-170),其数均分子量(Mn)在2.9×103~1.9×105之间,单位浓度聚合物的粘度(ηred)在0.06~0.49mL/g之间。通过FTIR和1H NMR对聚硅氮烷结构进行了表征,该系列聚硅氮烷具有无定型结构,可溶解于正己烷、甲苯、乙酸乙酯、二氯甲烷和N,N-二甲基甲酰胺等常用有机溶剂中,通过TGA分析了该系列聚硅氮烷的热性能,发现随着聚硅氮烷分子量的增加,在N2中25~700℃热解后剩余物的百分含量逐渐升高,最高可达72.58%。     

Improvement of thermal stability of UV curable pressure sensitive adhesive by surface modified silica nanoparticles

Pressure sensitive adhesives (PSAs) with higher thermal stability were successfully prepared by forming composite with the silica nanoparticles modified via reaction with 3-methacryloxypropyltrimethoxysilane. The acrylic copolymer was synthesized as a base resin for PSAs by solution polymerization of 2-EHA, EA, and AA with AIBN as an initiator. The acrylic copolymer was further modified with GMA to have the vinyl groups available for UV curing. The peel strength decreased with the increase of gel content which was dependent on both silica content and UV dose. Thermal stability of the composite PSAs was improved noticeably with increasing silica content and UV dose mainly due to the strong and extensive interfacial bonding between the organic polymer matrix and silica.     

Role of precursor chemistry on synthesis of Si–O–C and Si–O–C–N ceramics by polymer pyrolysis

In this study, the role played by polymer precursor chemistry on the nature of the pyrolyzed product was examined. Variables examined included extent of conjugation of the precursor, differences between a homopolymer and co-polymer, linear and cyclic structures, siloxanes and silazanes and between vinyl and phenyl containing silanes. Results indicate increasing the vinyl content of the precursor increases the amount of free carbon in the pyrolyzed product. The introduction of an aryl group in the silane decreased yield and lastly there was no change in the yield when a silazane was used instead of a silane, however, the composition of the silazane precursor ceramic is rich in nitrogen while a silane precursor ceramic is rich in carbon.     

MAA存在下VAc／BA核壳乳液聚合动力学研究

研究了功能性单体MAA的加入方式,乳化剂量和单体的加料速率等因素对MAA存在下VAc/BA核壳乳液聚合动力学的影响,同时探讨了动力学对胶粒形态变化和羧基分布的影响,研究表明,功能性单体MAA的加入方式不同会影响到壳层聚合阶段的溶胀、因而,使形成壳层的机理不同,乳化剂量和加料速率分别通过影响胶粒数和总体反应速率系数而对胶粒溶胀和壳层聚合反应产生影响。由于胶粒内聚合物浓度高、粘度大、因而胶粒形态变化受动力学影响甚大,羧基分布主要是由动力学确定的。     

聚硅氧烷的紫外光固化特性及热解机理研究

通过调聚法合成了不同乙烯基含量的聚硅氧烷,利用红外光谱和凝胶渗透色谱对聚合物进行了表征.研究了光引发剂、固化氛围、乙烯基团含量对所制备聚硅氧烷紫外光固化行为的影响;并利用热失重分析仪对固化物的热解机理进行了探讨.实验表明在氮气气氛下,以IHT-PI-185为光引发剂,随着聚合物中乙烯基团含量增加,固化速率加快,且固化后聚合物的耐热性能提高.     

On the UV-induced polymeric behavior of Chinese lacquer

To dry Chinese lacquer rapidly for the protection and restoration of archeological findings coated by lacquer or excavated lacquer wares and the development of new application of this lacquer, we carried out UV curing technology to improve its curing rate using a high-pressure mercury lamp as a UV source in the absence of any additional photoinitiator. The effects of mainly specific components in Chinese lacquer sap and the role of each reactive group of urushiol, namely hydroxyl groups, hydrogen on the phenyl ring, and olefins in the side chain, in the course of UV exposure were well-investigated. The UV-cured Chinese lacquer films were also characterized by FT-IR, (1)H NMR, SEM, TGA, and Py-GC/MS. The results showed that urushiol was the main component to form Chinese lacquer films, and decomposed to generate the urushiol semiquinone radicals, which sequentially induced the polymerization of Chinese lacquer by radical polymerization, as well as radical substitution under UV irradiation. In addition, the TG analysis suggested that polysaccharide and glycoproteins were integrated with the UV-cured films by covalent bonding. Furthermore, this method could be suitable to fast cure other phenol bearing long aliphatic unsaturated chain, such as CNSL.     

反相悬浮淀粉接枝共聚微球反应的动力学

以K<,2>S<,2>O<,8>-Na<,2>SO<,3>氧化还原体系为引发剂,研究了可溶性淀粉与N,N'-亚甲基双丙烯酰胺在反相悬浮体系中的接校共聚动力学.考察了引发剂、交联剂、淀粉、分散剂浓度和反应温度对聚合速率的影响规律.结果表明,在实验考察范围内的动力学关系式为R<,p>oc[I]<'0.89>[M]<'1.4...     

Thermal analysis,Raman spectroscopy and scanning electron microscopy of new polymeric material containing in-chain ruthenium complex: Poly-{trans-[RuCl2(vpy)4]-co-styrene} and poly-{trans-[RuCl2(vpy)4]-4 vinylpyridine-styrene}

This work reports the preparation and characterization of the binary copolymer poly-{trans-[RuCl₂(vpy)₄]-co-styrene} and the terpolymer poly-{trans-[RuCl₂(vpy)₄]-4 vinylpyridine-styrene}, obtained through the chemical reaction between trans-[RuCl₂(vpy)₄] (vpy is 4-vinylpyridine), 4-vinylpyridine and styrene (ST) using benzoyl peroxide. The synthesis was controlled by thin layer chromatography (TLC) and by monitoring the viscosity of the reaction medium. The resulting copolymers are characterized by means of UV–vis. spectroscopy, thermal analysis, Raman spectroscopy and scanning electron microscopy (SEM). The thermal properties of the copolymer were reported by differential scanning calorimetry (DSC), thermogravimetric and differential thermal analysis (TG/DTA) and dynamic–thermal–mechanical analysis (DTMA). Raman spectroscopy results showed that the polymerization takes place from both the vinyl group of the metal complex monomer and the vinyl group of the vinyl monomer, demonstrating the complex incorporation in the polymer matrix. Additionally, the Raman results showed that the redox polymer structure of the copolymer is very similar to that of the monomer. The properties of both materials are discussed.