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。     

ATRP法合成甲基丙烯酸羟丙酯

以2-溴丙酰溴为溴化剂,在离子液体([Amim]Cl)中与纤维素反应制备大分子引发剂,以溴化亚铜/五甲基二乙烯三胺(CuBr/PMDETA)为引发体系,N,N-二甲基甲酰胺(DMF)及丁酮(Butanone)为溶剂,研究了甲基丙烯酸羟丙酯的原子转移自由基聚合(ATRP)。通过FT-IR,1HNMR和GPC对聚合物进行了分析,考察了聚合反应的活性特征,反应时间、催化体系、溶剂对聚合物分子量及分子量分布的影响。结果表明,反应转换率随时间呈线性增加,且合成反应是可控活性聚合。     

纤维素-甲基丙烯酸丁酯的原子转移自由基聚合

以2-溴异丁酰溴为溴化剂,在离子液体([Amim]Cl)中与纤维素反应制备溴化纤维素大分子引发剂,以溴化纤维素/CuBr/N,N',N',N″,N″-五甲基二乙烯基三胺(PMDETA)为引发体系,N,N-二甲基甲酰胺(DMF)为溶剂,研究了甲基丙烯酸丁酯(BMA)的原子转移自由基聚合反应(ATRP)。合成了结构明晰的以纤维素为主链,聚甲基丙烯酸丁酯为支链的接枝共聚物Cellulose-g-PBMA。通过FTIR、1HNMR和GPC分别对大分子引发剂和接枝聚合物进行了分析。考察了聚合反应的活性特征,反应时间、催化体系、溶剂对聚合物相对分子质量(简称分子量,下同)及分子量分布的影响。结果表明,聚合反应转换率随时间呈线性增加,反应过程是活性可控聚合,催化剂和溶剂分别选用PMDETA/CuBr和DMF使反应更高效。     

巯基链转移聚合法制备超支化聚甲基丙烯酸-β-羟乙酯

设计并合成新型含被保护巯基的苯乙烯型AB单体,并以其为支化单体,甲基丙烯酸-β-羟乙酯(HEMA)为聚合主单体,DMSO为聚合溶剂,AIBN为引发剂,自由基聚合法制备可溶于水的超支化聚甲基丙烯酸-β-羟乙酯(PHEMA),同时建立一种新型超支化聚合法——巯基链转移超支化聚合法。用凝胶渗透色谱、1HNMR、DSC等对AB支化单体、PHEMA进行一系列结构和性能表征。实验结果表明,随着AB支化单体加入量的增加,聚合物的重均分子量Mw逐渐增加,而其Tg则呈下降趋势,在水中溶解度增加,说明聚合物发生超支化。     

[AMIM]Cl离子液体中纤维素接枝PDEAEMA分子刷的均相可控聚合

在氯化1-烯丙基-3-甲基咪唑([AMIM]Cl)离子液体中,采用原子转移自由基(ATRP) 法接枝改性微晶纤维素,合成了微晶纤维素-g-甲基丙烯酸二乙氨基乙酯(MCC-g-PDEAEMA)聚合物分子刷。通过加入助溶剂形成均相反应体系,解决了功能性单体甲基丙烯酸二乙氨基乙酯(DEAEMA)在[AMIM]Cl离子液体中的溶解问题。分别研究了离子液体中均相与非均相的反应机理,结果表明:在均相体系中,生成的反应副产物PDEAEMA较少,聚合物分子刷的接枝效率较高,分子量分布窄,ATRP反应可控性好。实验确定了均相体系最佳反应条件:CuBr/PMDETA/DEAEMA/乙醇的摩尔比为1:15:150:300, MCC-g-PDEAEMA的接枝效率可达78.1%。通过红外、核磁和GPC对聚合物表征发现,侧链PDEAEMA成功地接枝到微晶纤维素骨架上,生成的聚合物分子刷的分子量分布均匀。     

一种亲水性硅橡胶及其制备方法

正由枣阳市华威硅氟材料有限公司申请的专利(公开号CN110218453A,公开日期2019-09-10)"一种亲水性硅橡胶及其制备方法",涉及的亲水性硅橡胶配方为:硅橡胶90～100,甲基丙烯酸羟乙酯接枝聚合炭黑4～10,偶联剂2～5,硫化剂0. 5～1。该发明在炭黑表面接枝甲基丙烯酸羟乙酯,亲水性分子链增大了炭黑在硅橡胶中的分散性,且甲基丙烯酸羟乙酯接枝聚合炭黑与硅橡胶     

生物基多支化聚合物制备与表征(摘要)

<正>以纤维素、蓖麻油等可再生资源为原料,将甲基丙烯酸羟乙酯等石油基单体以及来源于可再生资源的松香基单体、油脂基单体以多种形式分别接枝到纤维素、蓖麻油骨干上,合成了具有刷状结构的纤维素基聚合物以及类似星状结构蓖麻油基聚合物,可制备出全生物基的新型高分子材料。通过采用傅里叶红外光谱(FT-IR)、核磁共振氢谱     

羟化含氟嵌段共聚物的合成

用α-溴代丙酸乙酯(EPN-B)/氯化亚铜(CuCl)/联二吡啶(bpy)作为ATRP催化引发体系,环己酮为溶剂,进行甲基丙烯酸2,2,2-三氟乙酯(TFEMA)的原子转移自由基聚合(ATRP),得到单分散PTFEMA-X预聚体。并以此预聚体为大分子引发剂引发甲基丙烯酸-β-羟乙酯聚合,得到分子质量可控、分子质量分布窄的聚甲基丙烯酸2,2,2-三氟乙酯-b-聚甲基丙烯酸-β-羟乙酯嵌段共聚物,用FTTR、~1H-NMR、GPC等对产物的结构与性能进行了表征。     

超细纤维素胶体和丙烯酰胺的接枝共聚

本文用纤维素材料经酸分解制备具有平衡聚合度（LODP）的微晶纤维素，再分散成超细纤维素胶体（准均相纤维素体系）。用扫描电镜（SEM）观察处理前后的纤维素颗粒尺寸，并比较它们和丙烯酰胺接枝共聚的反应速率、聚合转化率、接枝率、接技效率、聚丙烯酰胺支链的分子量及其分布的情况。     

RITP合成含氟两亲性嵌段共聚物PTFEMA-b-HEMA及其表征

使用可逆碘转移聚合(RITP)的方法,以I2作为链转移剂,合成了第一段为甲基丙烯酸2,2,2-三氟乙酯(TFEMA),第二段为甲基丙烯酸羟乙酯(HEMA)的两亲性嵌段共聚物TFEMA-b-HEMA,并对聚合物进行了FT-IR、1H NMR、GPC的表征。结果表明成功合成嵌段共聚物,并且分子量分散系数在1.4~1.6之间,达到活性聚合的效果。     

丙烯酸单体接枝纳米纤维素晶须的研究

以K2S2O8为引发剂,在纳米纤维素晶须(NCW)上接枝丙烯酸单体(AA),制备出丙烯酸接枝改性的纳米纤维素晶须.通过傅立叶变换红外光谱(FTIR)、透射电镜(TEM)、热重分析(TGA)等测试方法对接枝产物的性能进行了分析,并采用电导滴定的方法计算了接枝率以及表面取代基团含量.研究了反应条件对接枝率和接枝效率的影响.结果表明,在引发剂浓度为4 mmol/L,引发时间为5 min,纳米纤维素晶须与丙烯酸单体摩尔比为1: 1.5,反应时间为6 h的条件下,得到了接枝率为14.09%的丙烯酸接枝纳米纤维素晶须.实验证明,在NCW上可以接枝上丙烯酸,接枝率为14.09%的产物与NCW具有相似的表面形貌和热性能;TEM分析可知,接枝产物的分散性得到了提高;表面取代基团含量测试表明,接枝产物表面上的亲水性分散基团含量比NCW增加了5倍以上.     

Coil-to-rod conformational transition and single chain structure of graft copolymer by tuning the graft density

The chain conformation and individual chain structures of the graft copolymers ethyl cellulose grafting poly (acrylic acid) (EC-g-PAA) were investigated by laser light scattering (LLS) and atom force microscopy (AFM). The EC-g-PAA graft copolymers with two different side chain lengths and side chain grafting densities were synthesized via atom transfer radical polymerization (ATRP) from ethyl cellulose as the backbone. The graft copolymer molecules are adsorbed on the mica surface, and the observed single molecule structures by AFM reflect the molecular conformation in solution. An increase of the graft density of the graft copolymer induces the conformational transition due to the repulsion between side chains from coil to rod conformation. The observed disclike and rodlike single chain structures response to the coil and rod conformations, respectively. The results provide a direct visual experimental evidence of chain conformational and single chain structural transitions for graft copolymers in common solvents induced by graft density.     

Drag-reduction efficiency,shear stability,and biodegradation resistance of carboxymethyl cellulose-based and starch-based graft copolymers

Graft copolymers of carboxymethyl cellulose and starch with polyacrylamide have been synthesized by grafting acrylamide onto carboxymethyl cellulose and starch, respectively, using a ceric-ion-initiated solution polymerization technique. These graft copolymers have been tested for their drag-reduction effectiveness, shear stability, and biodegradability. It has been shown that grafting enhances the drag-reduction effectiveness and shear stability and also that these factors are very much dependent on the length and number of grafts in the molecule. None of the graft copolymer solutions shows any microbial degradation up to 10 days.     

Preparation,characterization, and properties of cellulose–polyacrylamide graft copolymers

Graft copolymers of acrylamide on cellulose materials (α‐cellulose 55.8%, DP 287.3) obtained from Terminalia superba wood meal and its carboxymethylated derivative (DS 0.438) were prepared using a ceric ion initiator and batch polymerization and modified batch polymerization processes. The extent of graft polymer formation was measured in graft level, grafting efficiency, molecular weight of grafted polymer chains, frequency of grafting as a function of the polymerization medium, and initiator and monomer concentrations. It was found that the modified batch polymerization process yielded greater graft polymer formation and that graft copolymerization in aqueous alcohol medium resulted in enhanced levels of grafting and formation of many short grafted polymer chains. Viscosity measurements in aqueous solutions of carboxymethyl cellulose‐g‐polyacrylamide copolymer samples showed that interpositioning of polyacrylamide chains markedly increased the specific viscosity and resistance to biodegradation of the graft copolymers. The flocculation characteristics of the graft copolymers were determined with kaolin suspension. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 913–923, 2003     

Synthesis and characterization of microcrystalline cellulose‐graft‐poly(methyl methacrylate) copolymers and their application as rubber reinforcements

In this study, redox‐initiated free radical graft copolymerization of microcrystalline cellulose (MCC) and methyl methacrylate (MMA) has been carried out in aqueous media to develop a novel cellulose‐based copolymer. Cerium ammonium nitrate was used as the initiator in the presence of nitric acid. Effects of monomer concentration, initiator concentration, polymerization time, and polymerization temperature on the graft parameters of copolymers were studied. The successful grafting copolymerization between MCC and MMA was validated through attenuated total reflection, wide‐angle X‐ray diffraction, field‐emission scanning electron microscopy, and thermal gravimetric analysis. In comparison to native MCC, the resultant copolymers exhibited enhanced thermal stability and better compatibility with natural rubber, suggesting its potential application as reinforcement material in rubber industry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42666.     

超声-微波共辐射法合成纤维素-MMA接枝共聚物

引言纤维素作为一种天然的可再生高分子材料,存在于丰富的绿色植物中,是自然界取之不尽用之不竭的清洁资源。因此,在煤、石油、天然气的储量日益减少的今天,纤维素可作为一种可持续发展的绿色资源来研究和开发。而且天然植物纤维资源丰富、价格低廉,并且具有较好的生物可降解性,在     

Synthesis of graft copolymers based on polyphenylene xylylene and fullerene grafted polystyrene

Graft copolymers containing poly(phenylene xylyene) (PPX) backbone and polystyrene fullerene (PSFu) grafting chains (PPX‐g‐PSFu) were prepared by using a purposed synthetic route comprising a combination of reaction mechanisms namely the modified Wessling route, an iniferter polymerization, and an atom transfer radical addition (ATRA). The monomer was first prepared by reacting dichloroxylene with tetrahydrothiophene. After that the monomer was polymerized in a sodium hydroxide solution to provide a polymer precursor. Subsequently, the polymer precursor was modified by reacting it with a dithiocarbamate (DTC) compound. The macroiniferter was obtained and then copolymerized with styrene and chloromethylstyrene via an iniferter polymerization. Finally, the graft copolymer was reacted with fullerene through an ATRA technique to attach the C60 groups onto the graft copolymer molecule. The products obtained from each of the steps were characterized by using various techniques including Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry, UV–visible spectroscopy, and thermal gravimetric analysis. The aforementioned results suggest that the graft copolymers were prepared. The grafting yield and grafting efficiency were found to increase with the monomers concentration and the amount of DTC used. Some homopolymer contaminants also occurred but those could be minimized and subsequently removed by extraction with selective solvents. These graft copolymer products might be used for the development of a bulk heterojunction polymer solar cell. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of ultra‐low molecular weight poly(vinyl alcohol) graft copolymer

Graft reaction of acrylamide (AM) and 4‐vinyl pyridine (4‐VP) onto ultra‐low molecular weight poly(vinyl alcohol) by ceric (IV) ion initiation had been systematically investigated; and the graft conditions were optimized by studying the effect of monomer/initiator concentration, solvents composition, reaction time and temperature. At optimized conditions, the maximum grafting efficiency and grafting ratio was ～ 50% and 51%, respectively with the presence of AM, whereas they decreased to 19% and 23%, respectively, without the presence of AM. Thermogravimetric analysis showed that as‐resulted graft copolymer had a lower thermal stability than homopolymer PVA. FTIR and ¹H‐NMR confirmed chemical structure of as‐synthesized graft copolymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

机械活化甘蔗渣与丙烯[BF]酸(钠)的接枝共聚反应

采用搅拌球磨对甘蔗渣进行机械活化,以不同活化时间的甘蔗渣为原料,过硫酸铵和亚硫酸钠为引发剂,在水溶液中与部分中和的丙烯酸进行接枝共聚反应。以接枝率和接枝效率为评价指标,考察了活化时间、丙烯酸与甘蔗渣的用量比、反应时间和反应温度等因素对接枝反应的影响。并采用SEM、FT-IR对甘蔗渣和产物进行表征。结果表明：机械活化明显强化了甘蔗渣与丙烯酸的接枝共聚反应,接枝率和接枝效率随着活化时间的延长而增大,主要是由于机械活化破坏了甘蔗渣中木质素对纤维素的包裹作用,降低纤维素的结晶度,提高了其反应活性。以活化1.5 h的甘蔗渣为原料进行接枝共聚反应,在反应时间为3 h、丙烯酸（体积,ml）与甘蔗渣（质量,g）的用量比为6、反应温度为60℃的条件下,制得接枝率和接枝效率分别为165.29%和82.70%的接枝共聚产物。