哌嗪—二氧化硫电荷转移复合物引发的甲基丙烯酸甲酯光聚合

本文研究了哌嗪（PPZ）与二氧化硫（SO2）电荷转移复合（CTC）的制备及其作为光引发剂引发甲基丙烯酸甲酯（MMA）的聚合,发现PPZ／SO2摩尔比聚合速率影响甚大,当PPZ／SO2为1：2时,形成了具有潜在引发能力的复合物（Ⅰ）,Ⅰ引发MMA光聚合的动力学关系式为RP＝Kp[ Ⅰ]^0.34[MMA]^1.06,表观活化能为23．7kJ/mol,并对引发机理进行了探讨。     

等离子体引发聚合甲基丙烯酸甲酯

甲基丙烯酸甲酯由等离子体引发聚合，其聚合速率与引发放电的持续时间以及后聚合条件有关。转化率以及聚合物的相对分子质量随后聚合时间的延长而增加。在反应初始阶段，聚合物相对分子质量已达２．５７×１０＾６。借助这一方法，可获得超高相对分子质量的聚合物。     

甲基丙烯酸甲酯的RAFT聚合研究

在链转移剂(CTA)二硫代苯甲酸异丙苯酯(CDB)、二硫代苯甲酸异丁氰酯(CPDB)和S,S′-二(α,α′-二甲基-α″-乙酸)-三硫代碳酸酯(CMP)的存在下,以甲基丙烯酸甲酯(MMA)为单体,采用可逆加成-断裂链转移(RAFT)聚合法合成聚甲基丙烯酸甲酯(PMMA)。研究了引发剂的用量、链转移剂与引发剂的物质的量比以及链转移剂的性质对聚合过程的影响。结果表明,对于三种CTA而言,偶氮二异丁腈(AIBN)用量为0.2%时聚合效果均最好;CTA的用量决定了聚合物的聚合度,减小CTA与AIBN的物质的量比可以得到相对分子质量较大的聚合物;在m(AIBN)∶m(MMA)=0.2%,n(CTA)∶n(AIBN)=4∶1时,三种CTA中CDB对此聚合过程的可控性最佳(相对分子质量分布指数为1.16),CPDB聚合得到的产物产率最高(86.5%),CMP聚合得到的产物数均相对分子质量最大(Mn=14 767g/mol)。     

甲基丙烯酸甲酯本体聚合动力学研究

对甲基丙烯酸甲酯（MMA）本体聚合动力学进行了研究。发现采用不同活性的偶氮二异丁腈和过氧化新癸酸叔丁酯单独引发MMA本体聚合．在不同含量下均出现明显的自动加速现象;在相同含量下,采用高低活性复合引发剂引发的MMA聚合动力学行为介于分别采用单一引发剂的聚合,但仍难消除聚合自动加速;采用聚合初后期高温、中期降温的聚合工艺对削弱聚合自动加速的效果较好。     

提高甲基丙烯酸甲酯光聚合收率的研究

以甲基丙烯酸甲酯(MMA)为单体,Fe Cl3·6H2O为催化剂,六次甲基四胺(HTMA)为配体,维生素C为还原剂,无水乙醇为溶剂,在2-羟基-2-甲基-1-苯基丙酮(1173)和四氯化碳(CCl4)双引发剂共同存在下,利用光聚合的方法,研究了单因素条件下MMA光聚合收率的工艺参数,并进行了优化。目标产物经红外分析表明,得到的聚合物是聚甲基丙烯酸甲酯(PMMA)。     

水溶性光引发剂二苯甲酮氯化铵引发三丙二醇双丙烯酸酯光聚合动力学的研究

以4-羟基二苯甲酮、环氧氯丙烷和三甲胺盐酸盐为原料,通过2步反应,合成了一种水溶性光引发剂——氯化[2-羟基-3-(4-苯甲酰基苯氧基)-N,N,N-三甲基-1-丙铵](HBPCl)。其结构通过核磁共振氢谱(1H-NMR)和傅里叶红外光谱(FT-IR)得到了证实。研究了水溶性光引发剂HBPCl的紫外吸收和降解特性,并通过实时红外(RT-IR)研究了氢助剂含量、HBPCl浓度和光强对HBPCl引发的TPGDA光聚合动力学的影响。结果表明,HBPCl在285 nm处有最大紫外吸收峰,能够有效地引发单体聚合;另外,随着氢助剂含量、引发剂浓度和光强的增大,光聚合速率和单体最终转化率随之增大,诱导期被缩短。     

丙烯腈光聚合研究

研究偶氮二异丁腈(AIBN)作光引发剂引发丙烯腈(AN)的光聚合,探讨了单体浓度、引发剂浓度、光照时间和环境温度对单体转化率、聚合物黏均相对分子质量的影响。总结出光引发剂C60-(SR)n(C60负载引发-转移-终止剂)与常规光引发剂AIBN引发AN光聚合的区别。     

双官能团引发剂引发甲基丙烯酸甲酯的聚合速率

研究了双官能团引发剂2,5-双(2-乙基己酰过氧化)-2,5-二甲基己烷（TX-141）引发甲基丙烯酸甲酯（MMA）的自由基聚合动力学,考察了引发剂浓度、聚合温度对聚合动力学的影响.结果表明：该体系的聚合活化能为91 kJ•mol^-1左右,计算得到TX-141引发剂的分解活化能为140 kJ•mol^-1左右,与实验值接近;TX-141引发剂的反应级数约为0.72,说明MMA聚合终止基元反应中单基和双基终止并存.同时与相似半衰期的过氧化二苯甲酰（BPO）比较,发现当TX-141引发剂浓度为BPO的1/2时,两者在各个聚合温度下的聚合动力学曲线几乎相同;但相对分子质量有明显增加,随聚合转化率增加,TX-141与BPO引发的聚合物数均分子量之比从1.2变化到1.33;由TX-141引发的聚合物低转化率时DSC曲线出现放热峰,而高转化率以及BPO引发的聚合物则没有.说明双官能团引发剂TX-141引发聚合时,在低转化率下TX-141引发剂的2个过氧键没有全部断裂,随聚合进行,断裂程度加深.     

新型有机盐光引发剂的双光子聚合特性研究

本文运用激光微细加工技术，通过对不同浓度引发剂的甲基丙烯酸类树脂的聚合行为进行评价，研究了1-甲基-2-[2-（9-戊基-咔唑-3-基）-乙烯基]-3，3-二甲基吲哚碘盐（Ⅰ）作为双光子光引发剂的聚合特性，结果表明该化合物在扫描速度为44μm／s时，双光子聚合阈值为139kJ／cm%2；当激光能量密度为286kJ／cm^2时，引发聚合的曝光时间阈值为0．7ms．实验结果为进一步作为双光子聚合三维结构的微细加工提供了可靠依据．     

巯基/烯紫外光聚合反应体系的研究及其应用

简要介绍了巯基/烯光聚合反应的机理,对该体系可降低氧阻聚作用和延迟凝胶的机理进行了讨论,介绍了巯基/烯体系在材料方面的应用,最后对该体系的研发趋势作了展望。     

4-乙烯基-4’-甲氧基二苯甲酮的光聚合性能研究

用萃取法研究了4-乙烯基-4’-甲氧基二苯甲酮(4-VMBP)和二苯甲酮(BP)在固化膜中的残留量;用实时红外法研究了4-VMBP的光聚合动力学,考察了胺浓度、引发剂浓度、灯距、氧阻、固化方式对氨基丙烯酸酯6116固化时间的影响。结果表明4,-VCBP固化残留量比BP小一个数量级;4-VMBP和三乙醇胺(TEOA)匹配性最好;固化体系中4-VMBP和TEOA质量分数均为4%时较为合适;隔绝空气条件下,固化时间缩短;灯距从10 cm调到20 cm,固化时间延长2倍多;间歇固化时间是连续固化的2倍多。     

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。     

Study of the cationic photopolymerization kinetics of cyclic acetals

Summary Photocationic polymerization for three cyclic acetals, namely 1,3-dioxolane, 1,3-dioxepane and 1,3,6-trioxocane, respectively, has been studied. Several cationic photo-initiators (diaryliodonium or triarylsulfonium salts, and one arene-metal complex) have been used. Differential scanning photo-calorimetry (DPC) has been employed to record the dependence conversion versus time. DPC thermogrames, in turn, have been utilized to calculate the propagation reaction constants as well as the corresponding activation energies. The values for the propagation constants at 30°C are 1.6·10² L/mol·s for 1,3-dioxolane, using a diaryliodonium salt as photoinitiator, 1.6·10³ L/mol·s for 1,3-dioxepane and 6.1·10³ L/mol·s for 1,3,6-trioxocane, respectively, in the presence of a triarylsulfonium salt as photoinitiator. The activation energies are in the range of 9.6÷19.6 kcal/mole. Received: 19 July 2000/Revised version: 8 November 2001/ Accepted: 8 November 2001     

Study of in-situ photopolymerization of chiral liquid crystal acrylate

The effect of the smectic and isotropic phase on the photo-polymerization of the chiral liquid crystalline 4-acryloxy-undecanyloxy-4′-[S(?)-2-methylbutyloxy]-biphenyl (monomer ( I )) was studied using FTIR. The effect of temperature on the birefringence of surface-oriented monomer ( I ) and its polymer obtained by in-situ photopolymerization was also investigated. The results show that photopolymerization in the isotropic phase proceeds at a higher rate than in the smectic phase, when monomer conversion is less than 60%; however, when monomer conversion is above 60%, the photopolymerization rate is independent of the initial phase state of monomer ( I ), and a highly oriented liquid crystalline polyacrylate film can be prepared by in-situ photopolymerization of the surface-oriented chiral acrylate ( I ).     

季戊四醇四(3-巯基丙酸)酯/乙烯基硅氮烷体系光聚合反应动力学红外光谱法研究

用傅立叶变换红外光谱法研究了季戊四醇四(3-巯基丙酸)酯/乙烯基硅氮烷体系光聚合反应动力学,跟踪检测了巯基和乙烯基吸光度的变化,测定了光聚合反应过程的巯基和乙烯基的转化率,发现巯基与乙烯基以化学计量比1∶1反应。在巯基和乙烯基物质的量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都得到较好的线性关系,且反应速率与巯基浓度的一次方成正比。     

Study on the structure and properties of Poly(methylmethacrylate)/Polypyrrole-Graphene Oxide nanocomposites

In this paper Poly(methylmethacrylate)/Polypyrrole-Graphene Oxide (PMMA/PPy-GO) nanocomposites were prepared using in-situ chemical polymerization method and its structure and properties were studied. Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis confirmed that PPy nanopraticles covered the GO nanosheets surface and PMMA/PPy-GO nanocomposite were prepared successfully. The mechanical, electrical and thermal stability of the PMMA nanocomposites were also investigated using Tensile, Impact, Thermogravimetric analysis (TGA) and four-point probe methods. Correlation between direct morphological observation and final properties demonstrated that network structure formed by PPy-GOs in PMMA matrix. Tensile analysis showed that the addition of 0.4 wt % PPy-GO hybrids lead to 24.4 % enhancement in the Young’s modulus of PMMA compared to 5.0 % improvement that achieved at the same loading level of GO. Electrical conductivity measurement showed that dispersion of PPy-GO in PMMA matrix increased AC conductivity in the range of 8 orders of magnitude compared to PMMA. TGA analysis showed that the thermal stability of the PMMA nanocomposites improved over 20 ?C.     

Architecture with photopolymerization

A brief summary of three-dimensional photopolymerization using visible light photoinitiators and polyfunctional acrylates is presented. The work is directed by an effort to build actual models, in real time, using laser-initiated photopolymerization in x, y layers of dimensional depth z.     

Triethylamine-sensitized photopolymerization of styrene

The photopolymerization of styrene in cyclohexane was accelerated by addition of triethylamine. The determination of the degree of polymerization of the polymer formed showed the acceleration was due to a concurrent sensitized initiation. Further kinetic studies revealed that the sensitization mechanism was analogous to that of the methyl methacrylate case reported earlier, in which an excited monomer and an amine formed an exciplex and gave an initiating radical species. The fluorescence of styrene was quenched effectively by addition of triethylamine in accordance with the kinetic argument.     

Adiabatic photopolymerization of acrylamide

Although the adiabatic polymerization of acrylamide using photoinitiation was first described over 30 years ago, it still offers convenient opportunities for innovation. In the present work, the effect of EDTA (ethylenediaminetetraacetic acid, tetrasodium salt) as a reducing agent with two photosensitizers is described. With riboflavin-5'-phosphate sodium, the rate of polymerization rises with the ? power of the EDTA concentration. With a new photosensitizer, 4-benzoyl-N,N,N-trimethylbenzenemethanaminium chloride, the rate rises with the ½ power of the EDTA concentration. Adiabatic temperature rise is used as the measure of conversion in the early stages of polymerization.