Ce(Ⅳ)盐引发丙烯腈在交联聚乙烯醇微球表面的接枝聚合

以戊二醛为交联剂,在反相悬浮体系中采用直接交联反应成球的方法,制备了聚乙烯醇(PVA)。以硫酸铈铵为引发剂,在酸性溶液聚合体系中实施了丙烯腈(AN)在交联微球CPVA表面的接枝聚合,制备了接枝微粒CPVA-g-PAN,考察了主要因素对交联成球反应与接枝聚合的影响规律。实验结果表明,在一定的搅拌速度下,分散剂用量及油水两相比是影响交联微球CPVA的主要因素。在Ce(Ⅳ)盐的氧化作用下,在含有大量羟基的CPVA微球表面会产生自由基,顺利地实现丙烯腈的自由基接枝聚合反应。反应温度、铈盐浓度和H+离子浓度是影响接枝聚合反应的主要因素。在适宜条件下,可制得PAN接枝度为27 g/100 g的接枝微球CPVA-g-PAN。     

聚酯纤维光接枝丙烯酸聚合反应动力学研究

实验考察了聚酯纤维接枝丙烯酸体系聚合温度、引发剂浓度、单体浓度与初始接枝聚合速率的依赖关系,结果表明光敏剂浓度与接枝率呈1.08次方关系,与单体浓度呈1.37次方关系。基于聚酯纤维光接枝聚合的终止反应主要是自由基单基终止反应的假设提出了相应的接枝聚合机理,并建立了聚合速率模型。聚合温度服从Arrhenius关系,得出了聚酯纤维接枝丙烯酸聚合反应表观活化能为29.33kJ/mol。     

LLDPE与甲基丙烯酸接枝共聚

采用溶液聚合和悬浮聚合法研究了线型低密度聚乙烯对甲基丙烯酸的接枝行为，发现溶液接枝法的产物有较高的接枝率，对铝箔的粘合力很强。     

季铵盐型抗菌纤维素纤维的辐射接枝聚合

固相表面接触抗菌材料应用于水的表面接触消毒是一项新的水处理技术,提高材料表面抗菌基团含量将有利于抗菌性能的提高。本研究采用直接辐射接枝和预辐射接枝两种方法,在纤维素纤维表面引入具有抗菌功能的季铵盐聚合物,详细探讨了两种辐射接枝聚合技术以及温度、时间、单体浓度、辐射剂量等具体辐射接枝聚合工艺参数对接枝聚合反应的影响。利用红外光谱（FTIR）、扫描电子显微镜（SEM）对接枝纤维素纤维进行了表征。结果表明,采用预辐射接枝技术可制得接枝率55%以上的高接枝率抗菌纤维素纤维。     

淀粉接枝丙烯酸聚合型絮凝剂的合成及絮凝性能研究

以可溶性淀粉为主要原料,以丙烯酸为接枝单体,硝酸铈铵和过硫酸钾为复合引发剂,采用溶液聚合的方法对糊化处理后的淀粉进行接枝聚合,合成出环保型淀粉衍生物水处理絮凝剂。通过对接枝聚合反应温度、反应时间、引发剂用量以及丙烯酸单体用量等因素对接枝率影响的研究,确定较佳的接枝产物合成条件：淀粉10g,单体丙烯酸用量10mL,硝酸铈铵和过硫酸钾（摩尔比1：1）复合引发体系用量2mmol,接枝反应温度50℃,接枝反应时间3h,接枝率达到43．2％。利用选煤后的废水对其产品絮凝性能进行实验研究,确定较佳的废水絮凝处理条件。     

聚丙烯无纺布预辐射法固相接枝甲基丙烯酸甲酯的研究

研究了以预辐射聚丙烯无纺布为基材,甲基丙烯酸甲酯为单体,采用固相接枝聚合的方法制备接枝共聚物的接枝反应过程。详细讨论了反应温度、反应时间、阻聚剂、单体浓度和交联剂等对接枝率的影响。结果表明,该接枝反应的最佳条件为:温度65℃、时间2 h、单体浓度20%、交联剂5%、阻聚剂(FeSO4.7H2O)0.3 g,在此条件下的接枝率为6.64%。     

聚丙烯无纺布预辐射固相接枝丙烯酸的研究

以聚丙烯(PP)无纺布为基材,以丙烯酸为单体,进行预辐射固相接枝聚合,考察了外部环境、辐射剂量、温度、反应时间、单体用量、介质、阻聚剂、交联剂对接枝率的影响。结果表明,通过预辐射固相接枝聚合方法,可将丙烯酸单体接枝在PP无纺布上,辐射剂量增大可提高接枝率;反应时间对接枝率的影响在低、高温阶段有所不同。最佳反应条件为:氮气环境,辐射剂量大于50 kGy,反应温度65℃,反应时间3 h,单体浓度30%,反应介质为水,阻聚剂0.8 g,交联剂用量为5 mL。     

淀粉-丙烯酰胺-甲基丙烯酰氧乙基三甲基氯化铵接枝共聚研究

采用氧化还原引发体系,在水溶液中接枝聚合制备了淀粉、丙烯酰胺(AM)与甲基丙烯酰氧乙基三甲基氯化铵(DMC)接枝共聚物。考察了反应温度、反应时间、引发剂浓度、单体质量比对接枝率、接枝效率及阳离子度的影响,确定了最佳反应条件:淀粉7.5g,AM15g,引发剂浓度0.4mmol/L,反应温度45℃,反应时间5h,m(DMC):m(AM)为1:3,所得接枝共聚物的接枝率为136.18%,接枝效率为79.8%,阳离子度为19.2%。     

原位分散聚合制备聚甲基丙烯酸甲酯/超细碳酸钙复合粒子

为了提高聚合物在超细碳酸钙粒子表面的接枝和包覆,对超细碳酸钙锚固偶氮引发剂及甲基丙烯酸甲酯(MMA)/改性碳酸钙原位分散聚合进行了研究. 碳酸钙粒子经氨基硅烷偶联剂处理后能与偶氮二氰基戊酸反应而实现锚固化,由红外光谱和元素分析证明了偶联和锚固反应.通过锚固在碳酸钙上的偶氮引发剂的引发作用,由MMA分散聚合制备了聚甲基丙烯酸甲酯(PMMA)接枝率高的PMMA/超细碳酸钙复合粒子,PMMA接枝率随聚合转化率增加而增加,而接枝效率随之降低;接枝PMMA的碳酸钙粒子在四氢呋喃和MMA中的分散稳定性明显优于未改性碳酸钙.     

K2S2O8-Na2S2O3引发淀粉与丙烯酸接枝产物吸水性能的主要影响因素

以玉米淀粉和丙烯酸为主要原料,采用溶液聚合的方法,制备了淀粉与丙烯酸接枝共聚物,用FTIR等方法对共聚产物结构进行了表征。研究了在过硫酸钾-硫代硫酸钠组成的氧化-还原引发体系中,引发剂、交联剂不同浓度及丙烯酸不同中和度等因素对共聚产物吸水性能的影响。实验结果表明采用K2S2O8-Na2S2O3引发体系,通过控制引发剂、交联剂浓度,接枝产物吸去离子水可达920 g/g;采用玉米粉代替玉米淀粉与丙烯酸接枝共聚,产物吸去离子水可达870 g/g;这些实验结果进一步提高了吸水树脂的吸水能力。     

A comparative study on effects of two kinds of polymerization methods on grafting of polymer onto silica surface

In this article we present the result of a comparative study of two kinds of polymerization methods—solution polymerization (sol. poly.) and dispersion polymerization (dis. poly.) for grafting polymer onto silica. As a model for the grafting polymerization reaction, styrene was chosen as the monomer and azo diisobutyronitrile (AIBN) as the initiator. The study aims at supplying theoretical reference for better selecting polymerization method to graft polymer on the silica particle surface. First, monolayers of 3‐methacryloylpropyl trimethoxysilane were chemically bonded onto the surfaces of micrometer‐sized silica gel particles, and so double bonds were immobilized onto the silica surface. Second, the copolymerizations between the immobilized double bonds and the monomer styrene were carried out, homopolymerizations of styrene followed, and finally polystyrene was grafted to the silica surfaces. Two kinds of polymerization methods, sol. poly. and dis. poly., were adopted respectively, and the effects of polymerization methods on grafting process were examined mainly. At the same time, the effects of different polymerization conditions on the grafting degree were researched. It was found that in the dis. poly. system the grafting degree is obviously higher than that in the sol. poly. system under the same polymerization conditions, and the grafting degree can go up to 47%, i.e. 47g/100g. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5808–5817, 2006     

‘Graft from’ polymerization on colloidal silica particles: elaboration of alkoxyamine grafted surface by in situ trapping of carbon radicals

We report in this paper an original method for the synthesis of polybutylacrylate grafted on silica particles. First, we use the Stoeber method to synthesize silica particles with a narrow size distribution. An initiator for radical-chain controlled polymerization is then grafted on the silica surface in two steps. Trimethoxysilylpropyl methacrylate (TPM) is first grafted on silica by simple condensation. Then, a alkoxyamine initiator N-tert-butyl-N-1-diethylphosphono2,2-dimethylpropyl-0,1-methoxycarbonyl ethylhydroxylamine (MONAMS) reacts with the CC double bond of the TPM to form the grafted initiator of radical polymerization. The last step is the grafting of butylacrylate. For this, we use living free radical polymerization that allows to control the molecular weight and the polydispersity of the polybutylacrylate chains. We show that this synthesis method makes it possible to obtain a colloidal suspension of silica particles having a mean size of about 88 nm, a weak polydispersity and an important grafting density of polybutylacrylate (PBA).     

原位聚合制备尼龙6/纳米SiO2复合材料研究

对原位聚合制备尼龙6／纳米SiO2进行研究。结果表明，无论是否对纳米SiO2复合材料进行偶联化处理，其表面均将在原位聚合过程中与尼龙6产生接枝；SiO2表面接枝物的生成，可在某种程度上造成体系结晶程度的降低，但复合体系的力学性能主要由SiO2粒子的分散程度、粒子和其体之间的相界面性质等因素决定；采用经偶联剂处理并具有较小粒径和较大比表面积的SiO2对尼龙6进行复合，可使复合体系的力学性能指标达到较高的水平，且硅烷偶联剂的最佳用是为SiO2的3％左右。     

Preparation and dispersibility of poly(L‐lactide)‐grafted silica nanoparticle

To improve dispersibility of silica nanoparticle in organic solvents, the grafting of poly(L ‐lactide) (PLLA) onto silica nanoparticle surface by ring‐opening polymerization of L‐lactide (LA) was investigated in the presence of an amidine base catalyst. The ring‐opening polymerization of LA successfully initiated in the presence of silica having amino groups (silica‐NH₂) and an amidine base catalyst to give PLLA‐grafted silica, but not in the presence of untreated silica (silica‐OH). In the absence of the amidine base catalyst no ring‐opening polymerization of LA even in the presence of silica‐NH₂ and no grafting of PLLA onto silica were observed. It became apparent that the amidine base catalyst acts as an effective catalyst for the ring‐opening graft polymerization of LA from the surface of silica‐NH₂. In addition, it was found that the percentage of PLLA grafting onto silica could be controlled according to the reaction conditions. The average particle size of PLLA‐grafted silica was smaller than that of silica‐NH₂. Therefore, it was considered that the aggregation structure of silica nanoparticles was considerably destroyed by grafting of PLLA onto the surface. The PLLA‐grafted silica gave a stable dispersion in polar solvents, which are good solvents for PLLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Studies on preparation of PGMA/Al2O3 and its effect on impact strength of epoxy resin

In this article, two kinds of methods for grafting polyglycidyl methacrylate (PGMA) onto Al₂O₃ surface by the radical polymerization initiated by peroxide groups and double bond groups, respectively, were investigated. In the first method, peroxide groups, as initiators, were immobilized onto the Al₂O₃ surface. Then, GMA was polymerized on Al₂O₃ under the radicals decomposed by peroxide groups, and PGMA was grafted onto Al₂O₃. But in the second method, 3‐methacryloylpropyl trimethoxysilane was chemically bonded onto the Al₂O₃ surfaces firstly to introduce double bonds. Secondly, the copolymerizations between the immobilized double bonds and the monomer GMA were performed, homopolymerizations of GMA followed, and finally PGMA was grafted to the Al₂O₃ surfaces. The effects of grafting methods on grafting degree were examined mainly. At the same time, the effects of different grafting conditions on the grafting degree were researched. Furthermore, the effect of the grafted particles PGMA/Al₂O₃ on impact strength of the epoxy composites was studied. It was found that the grafting degree achieved by the first method was much higher than that by the second, and the grafting degree can reach about 54%. Moreover, the impact strength of epoxy composites containing PGMA/Al₂O₃ particles were improved largely, and which increased with the grafting degree. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of tall oil fatty acids-based alkyd resins and alkyd–acrylate copolymers

The polymerization and properties of environmentally friendly waterborne binders for wood coatings were studied. Conjugated and non-conjugated tall oil fatty acids-based alkyd resins were synthesized and further copolymerized via miniemulsion polymerization with acrylates (butyl acrylate and methyl methacrylate). The ratio between alkyd resin and acrylate monomers was varied and the effect on copolymerization and the copolymer binder properties, such as particle size, molecular weight, grafting of acrylate to alkyd resin and reaction of double bonds, were studied. It was observed that the use of MMA influenced on the degree of grafting of acrylate and monomer conversion because the steric hindrances prevent MMA to react with alkyd double bonds as eagerly as BA. The increasing amount of alkyd resin was noticed to decrease the polymerization rate. The research showed that it was possible to prepare stable hybrids, alkyd–acrylate copolymers, with varied chemical composition.     

Preparation of acrylate polymer/silica nanocomposite particles with high silica encapsulation efficiency via miniemulsion polymerization

Acrylate polymer/silica nanocomposite particles were prepared through miniemulsion polymerization by using methyl methacrylate/butyl acrylate mixture containing the well-dispersed nano-sized silica particles coupling treated with 3-(trimethoxysilyl)propyl methacrylate (MPS). The encapsulation efficiency of silica particles was determined through the elution and hydrofluoride acid etching experiments, and the size distribution and the morphology of the composite latex particles were characterized by dynamic light scattering and transmission electron microscopy. The coupling treatment of silica with MPS can improve the encapsulation efficiency of silica and the degree of grafting of polymer onto silica. When 0.10 g MPS/g silica was used to modify silica, the encapsulation efficiency of silica was greater than 95%, and the degree of grafting of acrylate polymer onto silica was about 60%. Although the average size and the size distribution index of the composite latex particles increased as the weight fraction of silica increased, the stable latex containing the ‘guava-like’ composite particles was obtained. The grafting of polymer onto silica particles improved the dispersion of silica particles in the solvents for acrylate polymer and in the polymer matrix.     

Synthesis and characterization of poly(butyl acrylate)/silica and poly(butyl acrylate)/silica/poly(methyl methacrylate) composite particles

Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006     

Synthesis of hybrid free and nanoporous silica aerogel‐anchored polystyrene chains via in situ atom transfer radical polymerization

Polystyrene nanocomposite with mixed free and anchored chains was synthesized by atom transfer radical polymerization. Attachment of 3‐(trimethoxysilyl)propyl methacrylate with a double bond on the nanoporous silica aerogel surface results in a double bond grafted silica aerogel which could be incorporated into the polystyrene chains by a grafting‐through process. Conversion and molecular weight evaluation was carried out using gas chromatography and gel permeation chromatography, respectively. Double bond containing silica aerogel has an inconsiderable effect on conversion. There is no considerable discrepancy between the molecular weights of the free and anchored chains. Addition of silica aerogel with pendant CC bonds leads to increase of apparent rate constant of polymerization and also molecular weights. This is mainly because of initiator trapping in silica aerogel pores. Every percent of double bond containing silica aerogel with respect to styrene results in trapping of about 0.08 mol of ethyl alpha‐bromoisobutyrate among the silica pores. POLYM. COMPOS., 34:1648–1654, 2013. © 2013 Society of Plastics Engineers     

Dispersion of “guava-like” silica/polyacrylate nanocomposite particles in polyacrylate matrix

A series of “guava-like” silica/polyacrylate nanocomposite particles with close silica content and different grafting degrees were prepared via mini-emulsion polymerization using 3-(trimethoxysilyl)propyl methacrylate (TSPM) modified silica/acrylate dispersion. The silica/polyacrylate composite particles were melt-mixed with unfilled polyacrylate (PA) resin to prepare corresponding silica/polyacrylate molded composites and the dispersion mechanism of these silica particles from the “guava-like” composite particles into polyacrylate matrix was studied. It was calculated that about 110 silica particles were accumulated in the bulk of every silica/polyacrylate composite latex particle. Both the solubility tests of silica/polyacrylate composite latex particles in tetrahydrofuran (THF) and the section transmission electron microscope (TEM) micrographs of silica/polyacrylate molded composites indicated that the grafting degree of silica particles played a crucial role in the dispersion of silica/polyacrylate composite particles into the polyacrylate matrix. When the grafting degree of polyacrylate onto silica was in a moderate range (ca. 20%–70%), almost all of silica particles in these “guava-like” composite particles were dispersed into the polyacrylate matrix in a primary-particle-level. However, at a lower grafting degree, massive silica aggregations were found in molded composites because of the lack of steric protection. At a greater grafting degree (i.e., 200%), a cross-linked network was formed in the silica/polyacrylate composite particles, which prevented the dispersion of composite particles in THF and polyacrylate matrix as primary particles.