等离子体炭黑接枝聚合的研究

通过等离子体处理炭黑来引发乙烯基单体进行接枝聚合反应,并讨论了接枝反应的效果及影响因素。在炭黑颗粒上接枝不同的乙烯基单体会对炭黑体系的分散稳定性产生不同的影响。     

自炭黑表面开始的接枝聚合改性方法

系统介绍了在炭黑表面上引入活性质点,引发乙烯基单体和环状化合物等进行的自由基型和离子型接枝聚合改性方法。     

高吸水树脂的等离子体引发聚合反应制备研究进展

介绍了等离子体引发聚合反应的特点;综述了等离子体引发聚合反应在制备高吸水树脂领域的研究进展,包括等离子体引发乙烯基系列单体聚合制备高吸水树脂、等离子体引发乙烯基系列单体接枝共聚制备高吸水树脂、等离子体引发制备有机-无机复合高吸水树脂等;最后指出了等离子体引发制备高吸水树脂研究需要加强的几个方向:即加强对等离子体引发聚合制备高吸水树脂反应机理的研究;加强天然产物接枝系列、有机-无机复合系列高吸水树脂以及多功能高吸水树脂的等离子体引发聚合制备研究等。     

聚合物在炭黑表面的接枝反应

聚合物接枝炭黑的合成关于聚合物往炭黑表面上的接枝反应,已报导过多种方法,大体上可分为以下三类: ①在炭黑存在条件下,使用引发剂(游离基型或离子型),进行乙烯基单体的聚合,使系统内生成的增长聚合物链被炭黑表面捕获。     

聚合物表面光接枝改性研究进展

表面光接枝主要是用芳酮引发有机材料产生自由基，从而引发单体聚合产生表面接枝链。表面光接枝应用领域广泛．可用于聚合材料的表面改性以及表面功能化。综述了紫外光引发接枝改性聚合物表面的研究进展，包括光接枝聚合机理、改性方法、影响因素等，并对其应用前景及研究方向进行了介绍。     

离子液体中纤维素-甲基丙烯酸羟乙酯的均相聚合

在离子液体介质中利用原子转移自由基聚合方法合成了纤维素-甲基丙烯酸羟乙酯的接枝共聚物,采用甲基丙烯酸羟乙酯单体合成纤维素聚合物,并对聚合物进行结构测定与性质分析。通过FTIR、1HNMR和GPC对聚合物结构及相对分子质量(简称分子量,下同)进行分析,研究了不同溶剂对聚合条件、接枝效率的影响,以及在不同溶剂中聚合物的结构、分子量分布、热稳定性及形态有何变化。结果表明,在溶剂N,N-二甲基甲酰胺(DMF)中进行的反应聚合速率及终止速率均高于在丁酮中进行的反应。纤维素接枝甲基丙烯酸羟乙酯聚合物分子量分布约为1.81,该聚合物热稳定性较强;在DMF中呈球状颗粒,平均直径50 nm;在选择性溶剂丙酮中颗粒直径100 nm左右。     

炭黑表面聚合物接枝改性的研究进展

介绍了各种单体通过自由基聚合、阴离子聚合、阳离子聚合等机理在炭黑表面的接技改性及活性聚合物在炭黑表面的接枝反应的研究进展,归纳了改性炭黑的性能及其表征方法。     

离子液体中纤维素-甲基丙烯酸羟乙酯的均相聚合

在离子液体介质中利用原子转移自由基聚合方法合成了纤维素一甲基丙烯酸羟乙酯的接枝共聚物,采用甲基丙烯酸羟乙酯单体合成纤维素聚合物,并对聚合物进行结构测定与性质分析。通过FTIR,1H-NMR和GPC对聚合物结构及分子量进行分析,研究了不同溶剂对聚合条件与接枝效率的影响,以及亲水基团的引入聚合物的结构、分子量分布、热稳定性以及在不同溶剂中的形态有何变化。结果表明:在溶剂DMF中进行的反应聚合速率及终止速率均高于在丁酮中进行的反应。纤维素接枝甲基丙烯酸羟乙酯聚合物分子量分布在1.81左右,该聚合物热稳定性较强; 在DMF中呈球状颗粒, 平均直径50nm,在选择性溶剂丙酮中颗粒直径100nm左右     

水相悬浮接枝改性PP的研究进展

综述了化学接枝改性聚丙烯(PP)的方法。通过水相悬浮接枝法改性PP,不仅能够保持PP原有的性能,还能增加一些新的优异性能。PP的接枝多采用自由基引发,通过引发剂分解产生的初级自由基在PP分子链上夺氢,从而形成PP大分子自由基。PP大分子自由基与接枝单体接触,引发单体聚合,形成接枝链,反应遵循自由基聚合。对于水相悬浮接枝而言,单体的亲水性会影响接枝率,此外,不同单体的反应活性也不相同,对接枝效果也有着根本性的影响,还有一些其他因素(如引发剂、反应时间和温度)也会对接枝率造成影响。化学接枝改性PP的方法简单、反应条件温和、PP降解程度低、反应易控制、产物后处理简单、相对环保,具有良好的发展前景。     

碳化硅/炭黑悬浮体中丙烯酰胺单体自由基聚合的研究

采用2种引发体系引发碳化硅／炭黑悬浮体中丙烯酰胺单体的自由基聚合，通过测定单体聚合的热效应对丙烯酰胺单体的自由基聚合过程进行了表征，并分析了丙烯酰胺单体在碳化硅／炭黑悬浮体中的聚合机理。发现炭黑的存在不仅可以加速过硫酸铵分解，而且对丙烯酰胺单体的自由基聚合具有较强的阻聚作用，造成碳化硅／炭黑悬浮体聚合诱导期过短和单体聚合转化率较低。采用氧化还原引发体系可以提高单体转化率并实现单体聚合，但无法延长单体聚合的诱导期。通过在碳化硅／炭黑悬浮体中添加不同用量的缓聚剂乙酰丙酮，可以显著改善单体的聚合特性，不仅可以随意控制单体聚合的诱导期，而且还可以提高单体聚合的转化率，从而保证了碳化硅／炭黑悬浮体的凝胶注模工艺的实施。     

Plasma‐graft polymerization of a monomer with double bonds onto the surface of carbon fiber and its adhesion to a vinyl ester resin

Double bonds reactive with active radical species were introduced onto the surface of carbon yarn by the plasma‐graft polymerization of adipic acid divinyl ester and ethylene glycol dimethacrylate monomers to increase the adhesive strength in the interface between the carbon yarn and a vinyl ester resin. The degree of grafting increased with increasing polymerization time and polymerization temperature. The degree of grafting depended on both the solvent and the monomer species used in the polymerization, and a high degree was obtained with ethylene glycol dimethacrylate as the conjugated monomer and in a mixture of methyl isobutyrate and water. The grafted yarn, whose surface layer contained double bonds, was reacted with a vinyl ester resin containing benzoyl peroxide and N,N‐dimethylaniline. The pull‐out force of the yarn embedded in the resin increased with increasing degree of grafting. The failure in pulling out the yarn was cohesive. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2415–2419, 2003     

Grafting of methyl methacrylate onto cellulose nitrate initiated by benzoyl peroxide

It has been observed that grafting of vinyl monomers onto cellulose nitrate in solution takes place using benzoyl peroxode. The graft copolymer was isolated from the unreacted backbone and homopolymer by selective solvent extraction. The effect of variables, such as the initiator concentration, the monomer concentration and the reaction time on the percent grafting and the grafting efficiency, were discussed. A probable mechanism for grafting of vinyl monomers to cellulose nitrate in solution has been proposed.     

Temperature‐sensitive membranes prepared by the plasma‐induced graft polymerization of N‐Isopropylacrylamide into porous polyethylene membranes

A temperature‐responsive polymer, poly(N‐isopropylacrylamide) (PNIPAAm), was grafted onto porous polyethylene membranes by a plasma‐induced graft polymerization technique. A wide range of grafting was achieved through variations in the grafting conditions, including the postpolymerization temperature, time, monomer concentration, and graft‐reaction medium. The active species induced by plasma treatment was proven to be long‐living via a postpolymerization time of 95 h. Different solvent compositions, that is, water, methanol, benzene, and water/methanol, were used as reaction media, and water showed a much higher polymerization rate than the organic solvents. Based on the hydrophilicity of the active species, a mechanism explaining the solvent effect in plasma‐induced graft polymerization was examined. Characterizations by scanning electron microscopy, X‐ray photoelectron spectroscopy (XPS), and micro Fourier transform infrared showed that the grafted polymers were located on both the outer surface and inside pores of the membranes. The XPS analysis also confirmed that the polar amide groups tended to distribute more outward when grafted PNIPAAm was in its expanding state than when it was in its shrinking state. Water permeation experiments showed that the permeability of the grafted membranes varied dramatically with a slight temperature change in the vicinity of the lower critical solution temperature (LCST) of PNIPAAm. The effective pore radii of the grafted membranes above and below the LCST could be depicted by Hagen‐Poiseuille's law. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3180–3187, 2003     

Surface photografting polymerization of vinyl acetate,maleic anhydride,and their charge‐transfer complex. VIII. Charge‐transfer complex (4)

In view of the complexity of surface photografting polymerization of vinyl acetate/maleic anhydride (VAC/MAH) binary monomer systems, a novel method was adopted in the present article to obtain insight into the relevant grafting copolymerization mechanism. This method includes two steps: semibenzopinacol dormant groups were first introduced onto LDPE film by UV‐irradiation and then thermally reactivated to produce LDPE macromolecular free radicals, which initiated the grafting copolymerization of VAC and MAH. It was demonstrated that, in the first step, the solvent used to introduce benzophenone (BP) to LDPE film largely affected the subsequent grafting copolymerization, which was closely related to the affinity of the solvent toward the substrate. The monomer feed composition had considerable influence on both the grafting and nongrafting copolymerization; however, the maximum copolymerization rates did not appear in the polymerization system with [VAC]/[MAH] being 1 : 1, but, in the system with a bit more VAC than MAH, as the total monomer concentration was raised, the maximum copolymerization rates tended to appear in the system with [VAC] equal to [MAH]. The relationship between the total copolymerization rate (RP) and monomer concentration was determined to be LnRP ∝ [VAC + MAH]^1.83. All of these results indicated that both charge transfer (CT) complex formed by VAC and MAH and free monomers took part in grafting copolymerization. This feature differentiated the surface grafting copolymerization of VAC/MAH from the well‐studied thermally induced alternating copolymerization of VAC/MAH. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

侧基官能性乙烯基醚阳离子活性聚合与乙烯基醚阳离子光固化体系

本文着重介绍阳离子聚合单体的结构、溶剂及引发体系对活性阳离子聚合技术的影响以及近几年来采用活性阳离子聚合技术制备侧基官能性乙烯基醚聚合物的方法,尤其是应用较广泛的羟基、羧基、氨基等侧基官能化聚合物的合成。研究乙烯基醚阳离子活性聚合,将对乙烯基醚阳离子光固化体系的应用研究具有重要的指导意义。     

An example of free radical graft polymerization where the mechanism from-to applies

Free-radical grafting on natural and synthetic polymers is a method widely used to modify these polymers chemically. A number of these chemical systems show an unexpected behaviour of the polymerization rate when the monomer concentration is sufficiently high: it decreases and sometimes it increases afterwards. Here, the effect of varying the monomer concentration on the graft yield when grafting methyl acrylate, vinyl acetate and a mixture of both monomers onto cellulose initiated by ceric ions is discussed, considering a three-component mechanism of grafting (mechanisms from, onto and from-to). It is suggested that the unexpected behaviour indicated above is accounted for by the presence of the grafting mechanism from-to. Some knowledge about the copolymer structure can be reached by using this mechanistic approach.     

Vinyl polymerization: 414. Polymerization of vinyl monomer initiated by poly(N,N,N-trimethyl-N-2-methacryloxyethyl)ammonium chloride

The polymerization of vinyl monomer initiated by an aqueous solution of poly(N,N,N-trimethyl-N-2-methacryloxyethyl)ammonium chloride (poly(Q-DMAEM-CI) has been carried out at 85°C. The effects of the amounts of vinyl monomer, poly(Q-DMAEM-CI) and water on the conversion of vinyl monomer have been studied. The overall activation energy in the polymerization of MMA is estimated as 41.9 kJ mol^?1. The polymerization proceeds through a radical mechanism. The location in which the polymerization occurs is discussed. The selectivity for vinyl monomer is explained by ‘the concept of hard and soft hydrophobic areas and monomers’.     

Pervaporation of ethanol-water mixtures through poly(vinyl alcohol-g-acrylic acid) membranes prepared by use of Fenton's reagent in grafting

Ionic crosslinking of the ferric ions and the carboxylic groups in the poly(vinyl alcohol-g-acrylic acid) (poly(VA-g-AA)) membranes improves the size screening effect in the pervaporation of ethanol-water separation. In the grafting polymerization of acrylic acid monomer onto poly(vinyl alcohol) (PVA), ferric ions are remained in the polymer membranes as the Fenton's reagent(Fe²⁺-H₂O₂) is used to initiate the reaction. Completely reversed trends in terms of the degree of swelling, the pervaporation selectivity, and the flux of permeates are obtained depending on that the ferric ions are present or absent in the membranes. The degree of swelling decreases, the pervaporation selectivity increases, and the flux decreases as the grafting percentage increases for the membranes containing ferric ions. The degree of swelling and the flux of permeates increase but the pervaporation selectivity is reduced as the grafting percentage increases for the membranes which were washed with acid to remove ferric ions.     

Self‐driven graft polymerization of vinyl monomers on poultry chicken feathers in the absence of initiator/catalyst

An efficient and simple method for graft copolymerization of powdered chicken feather (CF) with vinyl monomers without any free radical initiator is reported. Various vinyl monomers such as glycidyl methacrylate (GMA), styrene (S), and methyl methacrylate (MMA); (20–60 wt % with respect to CF) were successfully grafted to chicken feather (CF) by using sodium dodecyl sulfate (SDS, 0.086–0.5 mmol) in the absence of any catalyst or initiator. Most likely, the hydrophilicity, hydrophobicity, and complex forming properties of chicken feather keratin with surfactant molecules were responsible for efficient grafting of polymers on CF surface. The effect of polymerization conditions, such as monomer concentration, temperature, and time of reaction, on the grafting parameters such as monomer conversion, grafting efficiency, and molar grafting ratio were studied. The described method showed a good potential of using low cost, easily accessible poultry chicken feathers as grafting material and self catalyzing agent for graft copolymerization with vinyl monomers to produce low cost commodity plastic for various end uses. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44645.     

Modification of polyolefin surfaces by plasma-induced grafting

Polar monomers have been grafted onto polyolefin surfaces with the aid of inert gas plasma. In the first stage, an inert gas plasma (argon plasma) was used to generate free radicals on the polyolefin surface. In the second stage, the plasma generator was turned off and a vinyl monomer introduced as a vapor. Monomer was surface grafted by free radical polymerization. After cleaning and drying, the samples were analyzed by XPS, IR, and contact angle. LD–PE was successfully grafted with acrylic acid, glycidyl methacrylate, methyl acrylate, and 2-hydroxy ethylacrylate. The grafting of acrylic acid was studied in more detail, and the rate of grafting was observed to increase with increasing monomer pressure and to decrease with time. The increasing of grafting temperature was found to reduce the degree of grafting. This last factor can be explained by the reduced concentration of monomer at the polymer surface or by a deactivation of surface radicals. © 1996 John Wiley & Sons, Inc.