在大孔硅基囊泡材料孔道内原位接枝有机聚合物

以聚环氧乙烷-聚环氧丙烷-聚环氧乙烷三嵌段共聚物(P123)为模板剂、正硅酸甲酯(TMOS)为硅源,采用水热法合成出孔径大于100 nm的硅基囊泡材料。同时采用两步法合成出带有硅烷偶联基团的有机自由基引发剂2-溴-2-甲基丙酸丁酯基三乙氧基硅烷(BPE)和2-溴-2甲基丙酸丁酯基二甲基氯硅烷(BPCM)。再利用偶联基团与囊泡材料孔道内表面的硅羟基偶联反应将自由基引发剂BPE和BPCM分别接枝到囊泡内表面,元素分析发现BPCM具有更高的接枝效率。然后在囊泡孔道内分别引发烯烃单体甲基丙烯酸甲酯(MMA)和甲基丙烯酸丁酯(BMA)的原子转移自由基聚合(ATRP)反应,使单体在表面自由基上逐一反应形成聚合物刷。透射电镜(TEM)表征结果表明,孔道内表面接枝上了聚合物后囊泡保持较为完好。通过化学方法将聚合物切割下来,凝胶渗透色谱(GPC)分析发现接枝的PMMA和PBMA的数均分子量(Mn)分别为7600和11400,分子量分布指数(PDI)均为1.25。     

正反向同时引发ATRP制备凹凸棒土/聚苯乙烯杂化粒子

通过脱醇法在凹凸棒土（ATP）表面接枝γ-氨丙基三乙氧基硅烷（APTES）实现氨基化（ATP-APTES）,再经酰胺化反应接枝α-溴代异丁酰溴,从而在ATP表面固载ATRP引发基团（ATP-Br）;最后以2,2-偶氮二异丁腈（AIBN）和ATP-Br为双组分引发体系进行正反向同时引发原子转移自由基聚合（SR&NI ATRP）制备ATP接枝聚苯乙烯杂化粒子（ATP@PS）。结果表明AIBN结合ATP-Br引发体系进行SR&NI ATRP具有活性/可控聚合的特征,随催化剂用量增大,体系过早偏离一级动力学行为。聚合温度在80℃,投料比为单体/催化剂/AIBN/ATP-Br=200/0.3/0.05/0.5的条件下,接枝聚合物和游离聚合物分子量差异随转化率（c）增大逐渐增加,转化率为31.1%时,两者分子量分布（PDI）均保持在1.54以下,ATP-Br表面ATRP引发基团的引发效率为6.3%。杂化粒子在PS基体中分散得到明显改善。     

硅橡胶表面亲水改性及其性质研究

采用等离子体处理硅橡胶表面,引入活性基团,然后将引发剂2-溴代异丁酰溴（BIBB）通过亲核取代接枝在含有活性基团的硅橡胶表面,最后采用表面引发原子转移自由基聚合（SI-ATRP）将聚乙烯基吡咯烷酮（PVP）接枝在硅橡胶表面。通过傅里叶变换红外光谱分析、X射线光电子能谱分析和场发射扫描电子显微镜分析证明,BIBB和PVP成功接枝到硅橡胶表面;通过水接触角测试发现,硅橡胶的水接触角由改性前的110.7°最大幅度下降至PVP接枝后的36°,PVP接枝改性硅橡胶的表面亲水性能得到明显改善。     

正反向同时引发ATRP制备凹凸棒土/聚苯乙烯杂化粒子

通过脱醇法在凹凸棒土(ATP)表面接枝γ-氨丙基三乙氧基硅烷(APTES)实现氨基化(ATP-APTES),再经酰胺化反应接枝α-溴代异丁酰溴,从而在ATP表面固载ATRP引发基团(ATP-Br);最后以2,2-偶氮二异丁腈(AIBN)和ATP-Br为双组分引发体系进行正反向同时引发原子转移自由基聚合(SRNI ATRP)制备ATP接枝聚苯乙烯杂化粒子(ATP@PS)。结果表明AIBN结合ATP-Br引发体系进行SRNI ATRP具有活性/可控聚合的特征,随催化剂用量增大,体系过早偏离一级动力学行为。聚合温度在80℃,投料比为单体/催化剂/AIBN/ATPBr=200/0.3/0.05/0.5的条件下,接枝聚合物和游离聚合物分子量差异随转化率(c)增大逐渐增加,转化率为31.1%时,两者分子量分布(PDI)均保持在1.54以下,ATP-Br表面ATRP引发基团的引发效率为6.3%。杂化粒子在PS基体中分散得到明显改善。     

功能性甲基丙烯酸甲酯-甲基丙烯酸缩水甘油酯嵌段聚合物ATRP合成

以2-溴代丙酸乙酯(EPN-Br)为引发剂,CuCl和2,2’-联二吡啶(BPY)为催化剂,以甲基丙烯酸甲酯(MMA)为原料,用原子转移自由基(ATRP)的方法,在80℃下合成带有卤原子的聚甲基丙烯酸甲酯大分子引发剂,在20～50℃下,以丁酮和正丙醇的混合液为溶剂,引发甲基丙烯酸缩水甘油酯(GMA)聚合,制得侧链含有环氧基团的PMMA-b-PGMA嵌段共聚物,分子量分布较窄,聚合物的分子量可通过单体与引发剂的比例进行控制。     

两个ATRP大分子引发剂的合成与表征

以十二醇为引发剂,通过开环聚合反应合成单端羟基的聚己内酯(PCL),将PCL进一步与α-溴丙酰溴反应,合成了原子转移自由基聚合(ATRP)的大分子引发剂-α-溴代丙酸聚己内酯。通过α-溴丙酰溴与聚乙二醇(PEG)的反应合成了另一种ATRP大分子引发剂-α-溴代丙酸聚乙二醇酯。用1H NMR和IR证实了这两种大分子引发剂的结构。     

基于点击化学和可逆加成-断裂链转移自由基聚合合成极性链接枝聚丁二烯

以1-硫代甘油作为改性剂、聚丁二烯为主链,通过热引发和光引发合成了侧基含有羟基的聚丁二烯,以S-1-十二烷基-S′（α-α′-二甲基-α′′乙酸）-三硫代碳酸酯作为可逆加成-断裂链转移自由基聚合试剂、偶氮二异丁腈为引发剂,合成了端羧基聚N,N-二甲基丙烯酰胺,然后将两种官能化的聚合物进行酯化反应制得聚N,N-二甲基丙烯酰胺接枝聚丁二烯。结果表明,采用光引发可以显著提高点击化学的反应效率。用核磁共振氢谱证实了产物含羟基聚丁二烯和端羧基聚N,N-二甲基丙烯酰胺以及接枝聚合物的结构,并显示通过这种方法所制备接枝聚合物的接枝链数目和长度均可控。     

利用原子转移自由基聚合法制备SiO_2/PAM纳米复合材料

为了改善二氧化硅(SiO_2)纳米粒子在聚合物基体中的分散性,采用原子转移自由基聚合(ATRP)法将聚合物接枝到纳米SiO_2表面。用甲苯-2,4-二异氰酸酯(TDI)对纳米SiO_2表面进行改性,然后与2-羟基-2′-乙基-2′-溴丙酸乙酯(HMB)反应,在表面引入ATRP引发剂,合成纳米二氧化硅颗粒(SiO_2-Br)。红外光谱(FT-IR)分析、热失重分析(TGA)和X-射线光电子能谱(XPS)结果表明,成功制备了SiO_2-Br引发剂,并通过ATRP法将聚丙烯酰胺(PAM)接枝到纳米SiO_2表面。通过凝胶渗透色谱(GPC)和分散性实验对改性后的样品进行了表征,结果表明,改性后的纳米SiO_2在甲苯中具有良好的分散性。     

新型有机硅表面施胶剂的合成及性能研究

采用自由基聚合法,使用过硫酸钾作为引发剂,以丙烯酰胺(AM)、八甲基四硅环氧烷(D4)为反应单体,制备一种施胶性能优异的有机硅-阴离子聚丙烯酰胺胺聚合物造纸施胶剂,考察了反应温度、引发剂用量、单体浓度等因素对分子量的影响,对其工艺条件进行探讨,得到较好的聚合条件,反应时间为3 h,单体浓度5%,反应温度为60℃,引发剂量为0.3%。在此条件下,制备的有机硅-阴离子聚丙烯酰胺聚合物疏水性好、增强性强,分子量高达2.09×10~6。通过红外光谱(FTIR)对结构进行表征。     

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。     

Controlled grafting from poly(vinylidene fluoride) microfiltration membranes via reverse atom transfer radical polymerization and antifouling properties

A reverse atom transfer radical polymerization (RATRP) with benzoyl peroxide (BPO)/CuCl/2,2-bipyridine (Bpy) was applied onto grafting of poly(methyl methacrylate) (PMMA) and poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) from poly(vinylidene fluoride) (PVDF) microfiltration (MF) membrane surfaces, including the pore surfaces. The introduction of peroxide and hydroperoxide groups onto the PVDF membranes was achieved by ultraviolet (UV) irradiation in nitrogen, followed by air exposure. RATRP from UV pretreated hydrophobic PVDF membranes was then performed for attaching well-defined homopolymer. The chemical composition of the modified PVDF membrane surfaces was characterized by attenuated total reflectance (ATR) FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The surface and cross-section morphology of membranes were studied by scanning electron microscopy (SEM). The pore sizes of the pristine PVDF and the PMMA grafted PVDF membranes were measured using micro-image analysis and process software. With increase of graft concentration, the pore size of the modified membranes decreased and became uniform. Kinetic studies of homogeneous (in toluene solution) system revealed a linear increase in molecular weight with the reaction time and narrow molecular weight distribution, indicating that the chain growth from the membrane surface was a “controlled” or “living” grafting process. The introduction of the well-defined PMMA on the PVDF membrane gave rise to hydrophilicity. Protein adsorption and protein solution permeation experiments revealed that the UV pretreated hydrophobic PVDF membrane subjected to surface-initiated RATRP of methyl methacrylate (MMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) exhibited good antifouling property.     

Novel Synthesis of Reactive Poly(ethylene glycol) grafted Poly(L-lactide) via Two Step Polymerizations

Summary Novel poly(L-lactide)-graft-poly(ethylene glycol) having reactive group at the end of grafted chain was prepared by two step polymerizations: ring-opening polymerization of L-lactide and 1,2-epoxy-5-hexene followed by radical polymerization of the product of ring-opening reaction and poly(ethylene glycol) methacrylate. Al(Et)₃·0.5H₂O and AIBN were used as catalyst and initiator for the two step polymerizations respectively. The structure of the synthesized polymers was also characterized.     

Surface modification of polythiophene and poly(3‐methyl thiophene) films by graft copolymerization

Polythiophene (PTH) and poly(3‐methyl thiophene) (PMT) films were electrochemically polymerized in an electrolyte solution of boron fluoride–ethyl ether. Ozone‐pretreated PTH and PMT films were subjected to UV‐light‐induced graft copolymerization with different monomers, including poly(ethylene glycol) monomethacrylate, acrylic acid, and glycidyl methacrylate. Surface grafting with the hydrophilic polymers gave rise to more hydrophilic PTH and PMT films. The structure and chemical composition of each copolymer surface were studied by X‐ray photoelectron spectroscopy. The surface grafting with the hydrophilic polymers resulted in a more hydrophilic PTH film. The dependence of the density of surface grafting and the conductivities of the grafted PTH and PMT films on the ozone pretreatment was also studied. A large amount of the grafted groups at the surface of the PTH and PMT films remained free for further surface modification and functionalization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Controlled atom transfer radical polymerization of MMA onto the surface of high-density functionalized graphene oxide

We report on the grafting of poly(methyl methacrylate) (PMMA) onto the surface of high-density functionalized graphene oxides (GO) through controlled radical polymerization (CRP). To increase the density of surface grafting, GO was first diazotized (DGO), followed by esterification with 2-bromoisobutyryl bromide, which resulted in an atom transfer radical polymerization (ATRP) initiator-functionalized DGO-Br. The functionalized DGO-Br was characterized by X-ray photoelectron spectroscopy (XPS), Raman, and XRD patterns. PMMA chains were then grafted onto the DGO-Br surface through a ‘grafting from’ technique using ATRP. Gel permeation chromatography (GPC) results revealed that polymerization of methyl methacrylate (MMA) follows CRP. Thermal studies show that the resulting graphene-PMMA nanocomposites have higher thermal stability and glass transition temperatures (T_g) than those of pristine PMMA.     

Synthesis of novel nanoreinforcements for polymer matrices by ATRP: Triblock poly(rotaxan)s based in polyethyleneglycol end-caped with poly(methyl methacrylate)

Poly(rotaxan)s of poly(ethylene glycol) and α-cyclodextrines (CD) block copolymers end-capped with poly(methyl methacrylate) chains were synthesized by atom transfer radical polymerization. The synthesized copolymers were characterized by ¹H NMR, 2D NOESY NMR, X-ray and Thermogravimetric analysis. Assuming a maximum relation of 2 CDs per ethyleneglycol unit, a coverage degree of 18% and 15% was achieved. X-ray analysis showed a characteristic signal around 20θ for all copolymers with an amorphous halo mainly due to inter-crystal poly(ethylene glycol) and poly(methyl methacrylate) chains. Full Molecular Dynamics of 20 ns was used to simulate the crystal structure of these copolymers. A pair correlation function was used to determine the coupling between hydrogen atoms of PEG, PMMA and cyclodextrine obtained by 2D NOESY NMR.     

Grafting of branched polymers onto nano-sized silica surface: Postgrafting of polymers with pendant isocyanate groups of polymer chain grafted onto nano-sized silica surface

To control the surface wettability of nano-sized silica surface, the postgrafting of hydrophilic and hydrophobic polymers to grafted polymer chains on the surface was investigated. Polymers having blocked isocyanate groups were successfully grafted onto nano-sized silica surface by the graft copolymerization of methyl methacrylate (MMA) with 2-(O-[1′-methylpropylideneamino]caboxyamino)ethyl methacrylate (MOIB) initiated by azo groups previously introduced onto the surface. The blocked isocyanate groups of poly(MMA-co-MOIB)-grafted silica were stable in a desiccator, but isocyanate groups were readily regenerated by heating at 150 °C. The hydrophilic polymers, such as poly(ethylene glycol) (PEG) and poly(ethyleneimine) (PEI), were postgrafted onto the poly(MMA-co-MOIB)-grafted silica by the reaction of functional groups of PEG and PEI with pendant isocyanate groups of poly(MMA-co-MOI)-grafted silica to give branched polymer-grafted silica. The percentage of grafting increased with increasing molecular weight of PEG, but the number of postgrafted chain decreased, because of steric hindrance. The hydrophobic polymers, such as poly(dimethylsiloxane) were also postgrafted onto poly(MMA-co-MOI)-grafted silica. It was found that the grafting of hydrophobic polymer and the postgrafting of hydrophilic polymer branches readily controls the wettability of silica surface to water.     

Graft copolymerization of vinyl monomers onto silk fibers initiated by a semiconductor‐based photocatalyst

Graft copolymerization onto silk (Bombyx mori) was carried out with vinyl monomers (methyl methacrylate and acrylamide) and initiated by a semiconductor‐based photocatalyst (cadmium sulfide). The utility of a semiconductor as an initiator in free‐radical photografting and the effects of ethylene glycol and triethylamine with cadmium sulfide on graft copolymerization were explored. Depending on the reaction conditions, 10–48% grafting with methyl methacrylate and 4–26% grafting with acrylamide were achieved. The reaction conditions were optimized, and the grafted fibers were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry analysis, and tensile strength measurements. The chemical resistance and water absorption of the grafted fibers were compared with those ungrafted fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

PMMA基稀土发光母料的制备及性能研究

采用硅烷偶联剂对稀土发光材料进行表面改性。将甲基丙烯酸甲酯、改性后的稀土发光材料和引发剂加入到聚合反应装置中,进行原位乳液聚合,制备聚甲基丙烯酸甲酯(PMMA)基稀土发光母料。红外光谱、热失重、扫描电镜分析表明,PMMA已经成功接枝到稀土发光材料表面,并以片状均匀地包覆于稀土发光材料表面。荧光光谱分析表明,乳液聚合过程中PMMA基稀土发光母料没有改变稀土发光材料的基质,PMMA基稀土发光母料的发光中心与稀土发光材料的相同,激发波长在可见光范围之内。     

Macromolecular anchoring layers for polymer grafting: comparative study

Comparative study of efficiency of macromolecular anchoring layers in the grafting of end-functionalized polymers to a surface was conducted. Poly(glycidyl methacrylate) (PGMA) and epoxydized polybutadienes (EPB) were utilized as the primary anchoring films. Amount of the epoxy moieties introduced to the surface was varied via thickness of the modifying polymer layer or amount of epoxy groups in the polymer backbone. Comparison between the grafting of polystyrene and poly(ethylene glycol) to the various macromolecular anchoring layers indicated that grafting ability of a layer was mostly governed by thickness of the interpenetration zone between the two polymers (anchoring and being grafted). In case of low level of the interpenetration, only functional groups at the periphery of the primary polymer layer were available for the grafting. Then, amount of grafted polymer did not increase with total number of epoxy groups in the anchoring film. However, as the thickness of the interpenetration zone increased, higher amount of the functional groups become available for the grafting.     

PMMA/PEG共混物形态和热性质的研究

在聚乙二醇存在的情况下,自由基聚合得到的聚甲基丙烯酸甲酯/聚乙二醇(PMMA/PEG)共混物,是一种半结晶聚合物;有相分离发生,一部分PEG晶体依然保持其晶体的特征,另一部分PEG晶体转变成非晶态,与PMMA网络复合,形成完全均一的非晶相。