乙二硫醇/乙烯基硅氮烷体系光聚合反应动力学的研究

采用傅立叶变换红外光谱法跟踪巯基和乙烯基吸光度的变化,跟踪测定了光聚合反应过程中巯基和乙烯基的转化率,研究了乙二硫醇/乙烯基硅氮烷体系的光聚合反应动力学.结果发现,巯基与乙烯基以化学计量比1∶1反应;在巯基和乙烯基的量之比相等和乙烯基过量的情况下,按照一级反应处理的动力学数据呈现较好的线性关系,且反应速率与巯基浓度的一次方成正比,与乙烯基浓度无关.     

巯基化合物／乙烯基聚硅氮烷光固化体系的研究

采用三种巯基化合物作为含乙烯基聚硅氮烷(PSN-1)的光固化剂,研究了三种巯基化合物与PSN-1的反应动力学,并对光固化产物进行了热重分析.结果表明:巯基化合物/ PSN-1体系的反应速率与巯基浓度的一次方成正比,与乙烯基浓度无关,均为一级反应;四元巯基化合物比二元巯基化合物的初始反应速率快,而转化率偏低;四巯基季戊烷/PSN-1体系的陶瓷产率高达89%,更适合作先驱体转化法制备陶瓷材料的陶瓷先驱体.     

巯基／乙烯基硅氮烷体系的紫外光聚合机理及动力学研究

乙烯基硅氮烷(VL20)是一种液态陶瓷前驱体,在光引发剂存在下与巯基化合物快速发生光聚合反应。文中利用先进的紫外光差示扫描量热(UV-DSC)实时跟踪和博里叶变换红外光谱(FTIR)原位跟踪等方法,研究了巯基-乙烯基硅氮烷VL20体系的光聚合反应机理和动力学特征。     

巯基/乙烯基硅氮烷紫外光固化的研究

利用原位红外跟踪技术和光-示差扫描量热技术研究了不同类型多官能巯基化合物与乙烯基硅氮烷的紫外光聚合动力学过程.结果表明,巯基化合物官能度越高,聚合反应速率越高,但最终转化率越低.巯基丙酸酯类化合物比烷基硫醇类化合物更易与乙烯基硅氮烷反应.在较低温度下,反应温度对聚合反应的影响较弱,反应活化能约为2.3kJ/mol,而较高反应温度下反应速率偏离Arrhenius方程.     

基于巯基-烯光点击聚合的抗菌有机硅涂层的制备与性能研究

有机硅聚合物常被作为医用材料,但现有的有机硅医用材料仍存在成型能耗高、细菌感染和生物污染等问题。本文合成了一种活性巯基聚硅氧烷,与乙烯基硅油混合后,在短时间内通过巯基-烯点击光聚合成有机硅涂层。此外,涂层中特有的硫元素带来了抗菌能力。结果表明,按照巯基-烯摩尔比1.5∶1充分混合后,在TPO光引发剂下,40 mW/cm³的紫外辐照强度可达到88%的反应转化率。另外,涂层样品对大肠杆菌和金黄色葡萄球菌都有明显的抑菌能力。     

LED封装用UV光固化硅树脂的制备及性能研究

通过水解-缩聚制备了不同分子结构的巯基硅树脂(MDT-SH),并将MDT-SH与乙烯基硅树脂和光引发剂配合,制备了紫外(UV)光固化硅树脂;然后对UV光固化树脂的光固化动力学进行了研究,对光固化制品的热稳定性、透光性和封装性能进行了详细分析。结果表明,当有机基团与硅的比值(R/Si)为1.88,巯基含量为0.34 mol/100 g时,MDT-SH硅树脂的相对分子质量分布较均匀且产率较高;当光引发剂2,4,6-三甲基苯甲酰基膦酸乙酯(TPO-L)的含量为1.0%、辐照强度为80 mW/cm^2、巯基与乙烯基摩尔比(SH/Vi)为1.5/1时,树脂可较快速交联成型;UV光固化树脂不仅具有优异的透光率和耐热性,且其封装发光二极管(LED)器件的性能明显优于市售道康宁封装胶OE-6550;有望替代传统热固型LED封装胶,实现规模化使用。     

超疏水硅烷化海绵的制备及其在油水分离中的应用

以四甲基四乙烯基环四硅氧烷与季戊四醇四-3-巯基丙酸酯作为光聚合体系反应物,通过简单浸涂和光固化巯基-烯点击反应制备了超疏水硅烷化海绵,并通过红外光谱、能谱和X射线光电子能谱等表征海绵表面光固化硅涂层结构。结果表明,所制备的硅烷化海绵具有良好的疏水性,表面静态水接触角可达(151.4±3.2)°;硅烷改性的海绵具有优异的吸附能力,吸附量可达自身质量的42.6~128.4倍。     

相转移催化法合成3-巯基丙酸(4-乙烯基苯基)甲酯

对氯甲基苯乙烯(CMS)在相转移催化剂(PTC)催化下,与3-巯基丙酸钾进行亲核取代反应,制备了标题化合物。研究了溶剂、催化剂及反应温度对反应的影响,实验结果表明:以二甲苯为溶剂,以三乙胺为相转移催化剂,催化剂与CMS的物质的量之比为1∶10,80℃下反应8 h,3-巯基丙酸(4-乙烯基苯基)甲酯的产率达60.7%,HPLC分析得到产物纯度>98%,1HNMR分析确证了产物结构。     

Synthesis of 4-vinylbenzyi-3-mercaptopropionate by phase transfer catalysis

对氯甲基苯乙烯(CMS)在相转移催化剂(PTC)催化下,与3-巯基丙酸钾进行亲核取代反应,制备了标题化合物.研究了溶剂、催化剂及反应温度对反应的影响,实验结果表明:以二甲苯为溶剂,以三乙胺为相转移催化剂,催化剂与CMS的物质的量之比为1∶10,80℃下反应8h,3-巯基丙酸(4-乙烯基苯基)甲酯的产率达60.7％,HPLC分析得到产物纯度＞98％,1HNMR分析确证了产物结构.     

多乙氧基POSS的合成及在RTV硅橡胶中的应用

以乙烯基三甲氧基硅烷为原料,制备了八乙烯基笼型倍半硅氧烷（OvPOSS）;再与γ-巯丙基三乙氧基硅烷（KH580）进行巯基-烯点击反应,合成八聚（三乙氧基硅丙巯基二亚甲基）笼型倍半硅氧烷（POSS—TEOST）;将POSS—TEOST加入室温硫化（RTV）硅橡胶中,考察了其用量对RTV硅橡胶性能的影响。采用^1H／^13C／^29Si NMR、FT-IR等对POSS—TEOST进行了表征,并研究了POSS—TEOST用量对RTV硅橡胶热性能、力学性能、硬度的影响。结果表明,在OvPOSS与KH580的量之比为1：8时,OvPOSS上8个乙烯基全部与巯基进行了反应;随着POSS—TEOST用量的增加,硅橡胶的热性能大幅度提升,氮气氛围中最大分解温度提高了75℃,在空气氛围中最大分解温度提高了124℃;此外,硅橡胶的拉伸强度和硬度分别提高了78％和55％。     

Photocuring of a thiol‐ene system based on an unsaturated polyester

To produce a photocurable thiol‐ene system, unsaturated polyester was prepared from the condensation reaction of ethylene glycol, diethylene glycol, and fumaric acid. Diallyl groups were introduced into the ends of the unsaturated polyester by a sequential condensation reaction. The coating formulation studied contained an equimolar ratio of thiol and vinyl groups of the prepared unsaturated polyester, including 1 wt % Irgacure 184. The curing behaviors of the unsaturated polyester with multifunctional thiols were investigated using real‐time FTIR spectroscopy. The rates of disappearance of thiol and vinyl groups of the unsaturated polyester were similar, demonstrating that there was little free‐radical homopolymerization of the internal fumaric group or the end‐capped vinyl ether group during the photocuring process and that the thiol‐ene reaction is the dominant process. The kinetics of the model compounds demonstrated that the reaction of the terminal allyl double bond with the thiyl radical is faster than that of the internal fumaric double bond in the UV curing of the unsaturated polyester. The storage stability of the thiol‐ene system based on unsaturated polyester was effectively increased by the addition of N‐PAL. The Raman spectra revealed that the presence of a multifunctional thiol (penta 3‐MP4) in the coating formulation increased the degree of surface curing due to the chain‐transfer ability of the thiyl radical. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 342–350, 2005     

高收率美罗培南侧链中间体的合成

针对现有美罗培南侧链中间体（硫醇内酯）制备工艺成本较高、反应路线复杂、副反应多、收率及粗品纯度较低等缺点，研究了一种简便制备硫醇内酯的方法，通过将M1[(2S，4R)-2-羧基-1-(4-硝基苄氧羰基)吡咯烷)]羧基活化、羟基活化和硫化成环合为一锅法以及添加相转移催化剂法制备硫醇内酯，再进行开环反应得到美罗培南侧链。研究了氯甲酸异丙酯、甲基磺酰氯（MsCl）、三乙胺（TEA）、Na₂S·9H₂O和三类相转移催化剂[聚乙二醇类（PEG）、季铵盐类和冠醚类]的投料摩尔比对制备硫醇内酯收率和纯度的影响。制备硫醇内酯时加入相转移催化剂既可以加快反应的速率，又可以提高产品纯度及收率。n_M1∶n_{氯甲酸异丙酯}∶n_MsCl∶n_{\mathrm{N}{\mathrm{a}}_{\mathrm{2}}\mathrm{S}·\mathrm{9}{\mathrm{H}}_{\mathrm{2}}\mathrm{O}}∶n_{CTEA（羧基活化时所加TEA）}∶n_{HTEA（羟基活化时所加TEA）}∶n_催化剂为1∶1∶1.3∶1.3∶1.3∶1.2∶(0.07～0.16)，羧基活化和羟基活化反应温度均为-30～-17℃，羧基活化和羟基活化反应时间分别为15min、30min；硫化成环从-30～-17℃升温到0℃，升温反应时间为30min；回流温度为40℃，回流时间165min。硫醇内酯收率为98.4%，纯度为98.3%。     

High‐speed photocrosslinking of thermoplastic styrene–butadiene elastomers

Photoinitiated thiol/ene polymerization was used to crosslink a triblock styrene/butadiene/styrene (SBS) polymer of low vinyl content (8%). The crosslinking process was followed by infrared spectroscopy (loss of unsaturation), insolubilization, swelling, and hardness measurements. The photogenerated thiyl radicals react with both the vinyl and the 2‐butene double bonds of the copolymer. Concentrations of less than 1 wt % in the trifunctional thiol crosslinker and in the acylphosphine oxide photoinitiator proved to be sufficient to create, within 0.5 s, a permanent chemical network in the elastomeric phase. This UV‐curing technology was successfully applied to crosslink rapidly commercial SBS–Kraton® thermoplastic elastomers. It proved also effective in the case of the much less reactive triblock styrene/isoprene/styrene (SIS) polymer which contains no vinyl double bonds. The thiol/ene polymerization was shown to be a much more efficient process to crosslink SBS and SIS thermoplastic elastomers than was the copolymerization of the rubber double bonds with a diacrylate monomer. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1902–1912, 2000     

Novel thermal curing of cycloaliphatic resins by thiol–epoxy click process with several multifunctional thiols

Novel thermosets were prepared by the base‐catalysed reaction between a cycloaliphatic resin (ECC) and various thiol crosslinkers. 4‐(N,N‐Dimethylaminopyridine) (DMAP) was used as base catalyst for the thiol–epoxy reaction. A commercial tetrathiol (PETMP) and three different thiols synthesized by us, 6SH‐SQ, 3SH‐EU and 3SH‐ISO, were tested. 6SH‐SQ and 3SH‐EU were prepared from vinyl or allyl compounds from renewable resources such as squalene and eugenol, respectively. Thiol 3SH‐ISO was prepared starting from commercially available triallyl isocyanurate. A kinetic study of the mixtures was performed using differential scanning calorimetry. Stoichiometric ECC/thiol/DMAP formulations were cured at 120 °C for 1 h, at 150 °C for 1 h and post‐cured for 30 min at 200 °C. The materials were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis and dynamic mechanical thermal analysis. The results revealed that the materials obtained from the synthesized thiols had higher thermal stability and glass transition temperatures than those obtained from the commercial PETMP. In addition, all the materials obtained exhibited very good transparency. This study proves the ability of multifunctional thiols to crosslink cycloaliphatic epoxy resins, leading to more flexible materials than those obtained by cationic homopolymerization of ECC or base‐catalysed ECC–anhydride copolymerization. © 2017 Society of Chemical Industry     

有机硅接枝聚合法制备超疏水棉织物

以硝酸铈铵(CAN)为引发剂,含有乙烯基的聚二甲基硅氧烷(VPDMS)和八乙烯基八硅倍半氧烷(VPOSS)为原料,对棉布进行接枝聚合疏水改性;在此基础上,利用体系内残留的乙烯基与巯基单体进行点击反应,引入长链烷基单体和含氟单体。采用FTIR、XPS和SEM对改性后纤维表面化学结构、形貌进行了表征。结果表明,VPDMS、VPOSS成功接枝到纤维表面,且通过点击反应法实现了纤维的二次改性。通过接触角测量仪对改性后棉布的疏水性能进行测定,发现当使用多乙烯基聚二甲基硅氧烷(MVPDMS10%,10%指与硅原子相连的乙烯基物质的量占硅原子总物质的量的百分比为10%)与VPOSS共聚接枝改性时,改性棉布的水接触角可达153°,使用全氟癸硫醇(PFDCMC)进行二次改性后,改性棉布的水接触角可达164°。通过磨耗、耐水洗和耐酸实验发现PFDCMC二次改性棉布疏水性能最优,且具有自修复特性。     

Effect of poly(vinyl acetate/vinyl alcohol) copolymer with a thiol end group as a steric stabilizer on dispersion polymerization of styrene

In dispersion polymerization of styrene in ethanol, effects of a reactive steric stabilizer, poly(vinyl acetate/vinyl alcohol) copolymer with a thiol end group (P(VAc/VA)-SH), were investigated. In the absence of the thiol end group, the dispersion coagulated at the middle stage of the polymerization, while in the presence of the thiol end group, the polymerization proceeded successfully to result in close to monodisperse particles. The reactive thiol group acts as a site of formation of the block copolymer, that is, polystyrene-b-P(VAc/VA), which is utilized as an effective dispersant. From the measurement on molecular weights during the course of polymerization, two polymerization loci were realized. Addition of butyl methacrylate to styrene affected markedly not only rate of polymerization but also particle size. © 1996 John Wiley & Sons, Inc.     

Photocrosslinking of functionalized rubbers. X. Butadiene–acrylonitrile copolymers

The photocrosslinking of polyacrylonitrile‐block‐polybutadiene‐block‐polyacrylonitrile (ABA) was shown to proceed within seconds at ambient temperature upon UV exposure in the presence of an acylphosphine oxide photoinitiator. The curing process was followed by infrared spectroscopy, insolubilization, and hardness measurements. Complete insolubilization could not be achieved with the neat ABA rubber because of the poor reactivity of the 2‐butene double bond and the low vinyl content of the polybutadiene chain. The addition of multifunctional acrylate monomers (20 wt %) causes a substantial increase of both the reaction rate and the crosslink density of the polymer, which becomes completely insoluble in toluene in less than 1 s upon UV irradiation. An even greater effect was observed by using small amounts (1 wt %) of a trifunctional thiol crosslinker. Both the thiol and the photoinitiator concentrations were shown to affect the kinetics of the thiol–ene polymerization and the polymer network crosslink density. A direct relationship was found to exist between the swelling degree of the UV‐cured rubber and the interchain molecular weight of the network. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2204–2216, 2001     

Photopolymerization kinetics,photorheology and photoplasticity of thiol–ene–allylic sulfide networks

BACKGROUND: Thiol–ene networks are of interest due to their facile photopolymerization and their open network structure. In this work, an allylic disulphide divinyl ether monomer is reacted with tetrathiol and divinyl ether monomers, which allows the network structure to permanently change in shape if stressed while under irradiation. We also study the photo‐differential scanning calorimetry (DSC) kinetics and photorheology during cure and the dynamic mechanical properties after cure. RESULTS: The heat of polymerization is similar for the thiol–ene systems and suggests ca 80% conversion of the vinyl ether groups. An increase in the initiator concentration increases the photocure rate as expected. The activation energy for photopolymerization is 7.6 kJ mol^?1. DSC and rheometry studies show that the polymerization kinetics is slowed by the addition of the allylic disulfide divinyl possibly due to the formation of less reactive radicals. However, as shown by dynamic mechanical thermal analysis, the network structure is not changed very much by addition of this monomer. If radicals are generated by irradiation of a photoinitiator in the network while a stress is being applied, the polymer will permanently deform depending on the fraction of 2‐methylenepropane‐1,3‐di(thioethyl vinyl ether) in the network, due to a bond interchange reaction. CONCLUSION: The rate of thiol–ene reaction is slowed by the addition of the allylic disulfide divinyl ether. Photoplasticity is observed in the networks containing the allylic disulfide groups. Further work is required to optimize the extent of photoplasticity in these systems. Copyright © 2007 Society of Chemical Industry     

Copolymerization of vinyl chloride with 1-olefins. III. An investigation of the copolymerization reaction of vinyl chloride with 1-butene and 1-pentene

Series of suspension copolymerization of vinyl chloride with various contents of 1-butene and 1-pentene (5–30 mass%) were carried out under the same reaction conditions. By applying a method which utilizes periodic sampling of heterogeneous reaction mixture from the reactor during the reaction and a gas chromatographic determination of unreacted vinyl chloride in the sample, the conversion curves of vinyl chloride were determined and the initial reaction rates were compared.     

Kinetics of UV curable alkyl 3-mercaptopropionate-vinyl silizane

Photopolymerization of vinyl-containing liquid silizane preceramic monomers copolymerized with thiol monomers, based on a step-growth radical polymerization mechanism, is a novel, rapid, inexpensive and simple technique for producing preceramic structures from liquid precursors. The kinetics of alkyl 3-mercptopropionate-vinyl silizane under UV irradiation is investigated by using real-time Fourier transform infrared (FT-IR) and photo-differential scanning calorimetry (photo-DSC). The experimental results show preliminarily that: (1) about 80% conversion of vinyl group has been achieved in the presence of a low concentration photoinitiator under UV irradiation; (2) by increasing the functionalities of the thiol group, the peak rate of copolymerization increases and the final conversion of the vinyl group decreases; (3) the copolymerization is primarily a bimolecular radical termination process; (4) the copolymerization is first-order, i.e., its rate is proportional to the vinyl group concentration and independent of the concentration of thiol group.