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1.
自蔓延波聚合研究进展   总被引:2,自引:0,他引:2  
波聚合是指靠自身反应放热产生的热波维持反应进行而将单体转化为聚合物的聚合方法。由于波聚合不需要外界持续供热、无溶剂排放和反应设备简单,是一种节能无污染的低成本材料制备工艺,极具应用前景。本文综述了从发现波聚合至今已取得的研究成果,包括波聚合机理、聚合波产生并自蔓延的条件、波结构、传播速度、传播模式以及产物特征,并对波聚合工艺用于高分子材料的制备进行了评述。  相似文献   

2.
用光敏剂4,4′ 二(N,N′ 二甲基-氨基)苯甲酮(简称米氏酮,MK)、引发剂邻氯代六芳基双咪唑(o-Cl-HABI)和氢给体助引发剂十二烷基硫醇(SH)组成光敏引发体系。研究了在高压汞灯照射下,甲基丙烯酸甲酯(MMA)光聚合速率和该敏化体系每一个组分,包括MK、o-Cl-HABI、SH和MMA的关系,还研究了该体系在PS版材上的应用,并获得了很好的效果。  相似文献   

3.
胺类具有还原性, 可以与多种氧化剂构成氧化还原引发体系, 胺类可产生自由基, 引发乙烯基单体聚合。若乙烯基单体同时含有胺类基团, 则这类自身还原性引发型单体在氧化剂存在的情况下既参与链引发又参与链增长, 因此可以形成超支化聚合物。本文首先回顾了胺类氧化还原体系及其引发机理, 然后总结自身还原性引发型单体分别与过氧化物、二芳酮、高氧化态过渡金属盐类或超高价态过渡金属络合物等构成的可聚合的氧化还原引发体系。最后, 还比较了自身还原性引发型单体的氧化还原引发自由基聚合与自身氧化性引发型单体的自缩合原子转移自由基聚合在支化结构的形成与演化方式上的差别。  相似文献   

4.
等离子体引发聚合   总被引:7,自引:0,他引:7  
叙述了近下赤等离子体引发聚合反应的研究情况及其在表面改性与合成新型高分子材料等方面的应用。  相似文献   

5.
合成了一种可聚合双分子光引发体系——甲基丙烯酸-4-二苯酮甲酯(BPMM)光引发剂和甲基丙烯酸-3,4-亚甲基二氧基苯甲酯(MDBMM)助引发剂.采用含有水平样品支架的实时红外光谱仪(RTIR)监测光聚合动力学,动态力学分析仪(DMA)研究固化膜的机械性能.结果表明,聚合体系的聚合速率(Rp)和最终双键转化率(Pf)随MDBMM 浓度的增加而增加,但是,随BPMM的浓度变化出现一最佳值(0.8%);相同的聚合条件下,与传统引发体系相比,BPMM/MDBMM虽然引发活性较差,但是其固化膜的Pf和玻璃化转变温度以及在37℃左右的储能模量与传统引发体系相近,并且MDBMM作为天然可食用植物化学成分衍生物的特点使其有可能适宜于在生物相容性要求较高的领域中应用.  相似文献   

6.
香豆素酮染料;双咪唑;染料增感;长波长光敏引发聚合体系  相似文献   

7.
光聚合引发剂研究进展   总被引:4,自引:0,他引:4  
对最近几年光敏聚合引发体系的研究进展进行了评述,并就一些新型光敏引发体系及引发机理进行了介绍。  相似文献   

8.
原子转移自由基聚合(ATRP)作为一种有效的\"活性\"/可控聚合可对聚合物进行分子设计,制备结构和相对分子质量可控的各类聚合物,具有潜在而广泛的研究价值。本文综述了ATRP的研究进展,特别是对传统ATRP催化引发体系、RATRP催化引发体系、AGET ATRP催化引发体系、SR&NI ATRP催化引发体系、ICAR ATRP催化引发体系、ARGET ATRP催化引发体系、杂化或双金属催化体系等的催化引发机理进行了详细的介绍。并综述了ATRP聚合中各种实施方法如本体聚合法、溶液聚合法、悬浮聚合法、乳液聚合法等的研究现状。  相似文献   

9.
A sequential photoinitiation. phenomenon was found in the benzophenone/triethylamine/ MMA radical photopolymerization system, which leads to increase of molecular weight, amine content of polymer formed with progressive irradiation time. The results, obtained demonstrate that the sequential photoinitiation originates from the photoreaction of active amine groups at the polymer chains with excited benzophenones producing a polymer radicals, which induce sequential polymerization. The effects of benzophenone and amine concentrations,oxygen co-ntent and chain requlator were studied. Reaction mechanism was also discussed.  相似文献   

10.
过去,作者曾发表了多种光敏引发体系引发烯类单体光聚合的工作,在研究2,2-二甲氧基苯乙酮在氧存在下引发甲基丙烯酸甲酯光聚合时,结合在聚合物链端的引发剂碎片具有光化学活性,在光聚合反应中产生高分子自由基,发生再次聚合,出现高分子量  相似文献   

11.
The emulsion polymerization of vinyl acetate (VAc) was carried out by using redox initiation systems of different persulfate cations such as potassium persulfate (PPS), sodium persulfate (SPS), and ammonium persulfate (APS); each of them was coupled with developed acetone sodium bisulfite adduct (AcSBS) as a reducing agent. The rate of polymerization was found to be dependent on the initiator concentration to the powers 1.04, 1.02, and 0.34, respectively. The effect of the different cations of the oxidizing agents upon the stability of the prepared emulsion lattices was studied by using the sedimentation method. The effect of the different cations on the morphological characteristics of some of the produced lattices was also studied. Finally, the activation energies of these reactions for potassium, sodium, and ammonium persulfate were found to be 0.84 × 104, 1.92 × 104, and 6.68 × 104 J/mol, respectively. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3141–3149, 1997  相似文献   

12.
    
Chemical systems that remain kinetically dormant until activated have numerous applications in materials science. Herein we present a method for the control of gelation that exploits an inbuilt switch: the increase in pH after an induction period in the urease‐catalyzed hydrolysis of urea was used to trigger the base‐catalyzed Michael addition of a water‐soluble trithiol to a polyethylene glycol diacrylate. The time to gelation (minutes to hours) was either preset through the initial concentrations or the reaction was initiated locally by a base, thus resulting in polymerization fronts that converted the mixture from a liquid into a gel (ca. 0.1 mm min?1). The rate of hydrolytic degradation of the hydrogel depended on the initial concentrations, thus resulting in a gel lifetime of hours to months. In this way, temporal programming of gelation was possible under mild conditions by using the output of an autocatalytic enzyme reaction to drive both the polymerization and subsequent degradation of a hydrogel.  相似文献   

13.
<正> 有机过氧化二苯甲酰(BPO)与N,N-二甲基苯胺(DMA)组成的引发体系称为有机氧化还原引发体系.为了提高聚合速度和聚合物的颜色稳定性,发展了BPO-DMT(N,N-二甲基对甲苯胺)引发体系,并已应用于医用高分子的齿科材料和骨水泥中.文献[3]曾简单提到N,N-二2-羟乙基苯胺(DHEA)作为促进剂,其活性与DMA相似;另外BPO可分别与N,N-二(2-羟乙基)对甲苯胺(DHET)和N,N-二(2-羟丙基)对甲苯胺(DHPT)组成引发体系,作为烯类自由基聚合的室温固化剂,但对聚合速度和聚合动力学报道甚少.由于DHPT熔点较高又无刺激味道,因而很适用于自凝齿科林  相似文献   

14.
    
Thermal frontal polymerization is a process in which a localized reaction propagates through an unstirred system by the coupling of the thermal diffusion and the Arrhenius kinetics of an exothermic polymerization. A trithiol was found to affect the front velocity and the time for inducing a front upon exposure to UV light for trimethylolpropane triacrylate polymerization fronts with either kaolin or calcium carbonate filler present. The addition of trithiol and filler both decreased the front velocity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8091–8096, 2008  相似文献   

15.
以铈离子和酰苯胺引发体系进行丙烯酰胺的聚合,研究了不同结构酰苯胺对聚合的影响。在H_2O-CH_3CN(3∶1)介质中聚合时,乙酰对甲苯胺对聚合的促进作用最为明显,聚合速度可提高一个数量级。测定了聚合反应的表观活化能和聚合动力学方程、由聚合物的原子发射光谱,UV光谱和端基测定,提出了聚合反应机理。  相似文献   

16.
    
Frontal copolymerization is a process in which a spatially localized reaction zone propagates into a mixture of two monomers, converting them into a copolymer. In the simplest case of free‐radical copolymerization, a mixture of monomers and initiator is placed into a test tube. Reaction is initiated at one end of the tube, and a self‐sustained thermal wave, in which chemical conversion occurs, develops and propagates through the tube. We develop a mathematical model of the frontal copolymerization process and analytically determine the structure of the polymerization wave, the propagation velocity, maximum temperature, and degree of conversion of the monomers. Specifically, we examine their dependence on reactivity ratios as well as other kinetic parameters, monomer feed composition, and exothermicity of the reactions. Our analytic results are in good quantitative agreement with both direct numerical simulations of the model and experimental data, which are also presented in the paper.

Dependence of front velocity on monomer feed composition for different heat release parameters.  相似文献   


17.
    
Studies of the onium salt photoinitiated cationic ring‐opening polymerizations of various 3,3‐disubstituted oxetane monomers have been conducted with real‐time infrared spectroscopy and optical pyrometry. The polymerizations of these monomers are typified by an extended induction period that has been attributed to the presence of a long‐lived tertiary oxonium ion intermediate formed by the reaction of the initially formed secondary oxonium ion with the cyclic ether monomer. Because the extended induction period in the photopolymerization of these monomers renders oxetane monomers of limited value for many applications, methods have been sought for its minimization or elimination. Three general methods have been found effective in markedly shortening the induction period: (1) carrying out the photopolymerizations at higher temperatures, (2) copolymerizing with more reactive epoxide monomers, and (3) using free‐radical photoinitiators as synergists. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3205–3220, 2005  相似文献   

18.
    
Frontal polymerization of deep eutectic solvents (DESs) made with acrylic or methacrylic acid as the monomer and hydrogen bond donor was studied. Fronts with acrylic acid and choline chloride propagated more uniformly than with pure acrylic acid, so an exploration into how the DES affected frontal polymerization was performed. The hydrogen bond acceptor of the DES was replaced by several analogs to determine the effect on the DES front behavior. The analogs used were talc, DMSO, lauric acid, and stearic acid, which acted as a heat sink, inert diluent, hydrogen bonding diluent, and inert phase change material, respectively. None of the methacrylic acid‐analog systems were able to sustain a front. While the acrylic acid‐analog systems did sustain a front (with the exception of stearic acid), none of the fronts replicated the acrylic acid DES behavior. The acrylic acid–talc sample behaved more violently—like pure acrylic acid polymerization—than the acrylic acid DES, and the DMSO and lauric acid samples produced slower fronts than that of the acrylic acid DES. We propose that the reactivity of the acrylic acid and methacrylic acid is enhanced in the DES. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 4046–4050  相似文献   

19.
简要介绍含二苯酮基的大分子光敏引发剂的合成制备、引发聚合机理及应用方面的研究进展情况。  相似文献   

20.
    
In an effort to create frontal polymerization systems with a “fail‐safe” curing mechanism, we studied the effects of thiols on the thermal frontal polymerization velocity and pot life of a mixture of a multifunctional acrylate, kaolin clay (filler), and cumene hydroperoxide with either trimethylolpropane tris(3‐mercaptopropionate) or 1‐dodecanethiol (DDT). The acrylates were trimethylolpropane triacrylate, trimethylolpropane ethoxylate triacrylate, 1,6‐hexanediol diacrylate, and di(ethylene glycol) diacrylate. Without a thiol, frontal polymerization did not occur. The front velocity increased with the concentration of either thiol, which has not been observed with peroxide initiators. The use of DDT yielded longer pot lives than the trithiol. The front velocities were inversely related to the pot lives. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3850–3855  相似文献   

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