SiO2表面RAFT接枝聚合苯乙烯

基于纳米SiO2表面羟基与7-甲基丙烯酰氧基丙基三甲氧基硅烷间的偶联反应,在纳米SiO2表面引入可聚合双键。采用可逆加成断裂链转移（RAFT）聚合技术,以偶氮二异丁腈为引发剂,使SiO2表面接枝聚合苯乙烯。考察了二硫代苯甲酸异丁腈酯、二硫代苯甲酸苄酯、（1,2,4-三氮唑）基二硫代甲酸苄酯和二硫代新戊酸苄酯等对SiO2表面接枝聚合苯乙烯速率的影响。结果表明,SiO2表面接枝聚合苯乙烯的速率决定于RAFT试剂的Z基团结构。二硫代新戊酸苄酯调控的SiO2表面接枝聚合苯乙烯的速率最高。     

RAFT链转移剂存在下凹凸棒土表面甲基丙烯酸甲酯接枝聚合

将γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(MPS)接枝到凹凸棒土(AT)表面,制得表面带有可聚合碳碳双键的改性粒子AT-MPS;以二硫代苯甲酸氰基异丙酯(CPDB)为链转移剂,采用可逆加成断裂链转移(RAFT)聚合技术,在AT表面进行甲基丙烯酸甲酯(MMA)接枝聚合.通过红外(FTIR)、热失重(TGA)等方法进行了表征,考察了引发剂以及RAFT链转移剂用量对聚合反应动力学和AT表面接枝聚合接枝率的影响.结果表明,PMMA通过RAFT聚合成功接枝在AT表面;基于RAFT过程的接枝聚合比传统自由基接枝聚合具有更长的反应时间和较高的接枝率.本体系相对适宜条件:温度为70℃,[MMA]/[CPDB]/[AIBN]为400/1/0.5.此条件下聚合反应具有很好的可控性,溶液中的聚合物分子量分布指数为1.2~1.3,AT表面PMMA接枝率为16.33%.引发剂和RAFT链转移剂用量过大均会造成接枝率降低.     

RAFT自由基聚合技术在表面改性领域的研究进展

总结了近十年来可逆加成一断裂链转移（RAFT）自由基聚合技术在材料表面改性领域的研究进展。主要介绍了相关的四大类改性途径：（1）物理涂覆RAFT聚合物;（2）从表面接枝聚合（graftingfrom）,即在表面自由基和溶液中自由RAFT链转移剂存在下进行表面接枝聚合反应;（3）将聚合物接枝到表面（graftingto）...     

丙烯酰胺在炭黑表面接枝聚合研究

利用Ｃｅ＾４＋和羟甲基化炭黑组成的氧化还原引发体系，探讨了丙烯酰胺在炭黑表面的自由基水溶液接枝聚合机理。研究表明：单体浓度、硝酸浓度和铈盐用量直接影响丙烯酰胺在炭黑表面的接枝聚合，ＦＴＩ和ＴＥＭ分析证明：改性炭黑表面存在着聚丙烯酰胺。改性炭黑粒子的Ｚｅｔａ电位值与未改性炭黑粒子相同，但它与水组成的分散体具有极好的分散稳定性。     

等离子体引发HEMA的RAFT接枝聚合改性聚丙烯多孔膜

采用等离子体引发的可逆加成-断裂链转移(RAFT)接枝聚合法,以甲基丙烯酸羟乙酯(HEMA)为单体,对聚丙烯(PP)多孔膜表面作了亲水改性.研究了接枝聚合动力学,并以FT-IR、SEM、压汞、水通量等方法研究了改性膜的表面结构形态及孔结构.结果表明,等离子体引发的RAFT接枝聚合速率显著低于普通等离子体引发的接枝聚合速率.表面接枝率随着接枝聚合时间的延长呈线性增长趋势,同时改性膜的孔径和水通量随之减小.     

苯乙烯在炭黑表面的阴离子接枝聚合研究

利用正丁基锂（ｎ－ＢｕＬｉ）与炭黑（ＣＢ）表面含氧基团反应制得了表面含－ＯＬｉ基团的反应型炭黑，以该炭黑与聚氧乙烯－聚氧丙烯－聚苯乙烯（ＰＥＯ－ＰＰＯ－ＰＳ）多嵌段聚合物组成的阴离子引发体系作活性中心，研究了苯乙烯在炭黑表面的阴离子接枝聚合。ＦＴ－ＩＲ，ＴＥＭ和ＤＳＣ分析表明在接枝炭黑表面存在苯乙烯的聚合物。接枝炭黑在甲苯中有良好的分散稳定性。     

苯乙烯,丙烯腈在炭黑表面的阴离子接枝聚合

反应型炭黑;苯乙烯;丙烯腈在炭黑表面的阴离子接枝聚合     

纳米氧化硅表面阴离子接枝聚合苯乙烯

通过正丁基锂(BL)引发甲基丙烯酰氧丙基纳米氧化硅(MAMSN)与苯乙烯共聚,制备了聚苯乙烯表面接枝纳米氧化硅(PS—g—Silica),并考察了正丁基锂加入量对苯乙烯转化率(C)、接枝率(PG)以及聚苯乙烯分子量(Mn)的影响。实验结果表明,阴离子聚合可以获得比自由基聚合更大的分子量和更高的转化率以及接枝率。     

RAFT聚合制备结构明确的荧光标识聚甲基丙烯酸甲酯

以铁氰化钾为氧化剂,通过N-咔唑二硫代甲酸钠的水相氧化制备了高纯度的中间体二硫化双(N-咔唑硫代甲酰)(DTCD),DTCD以晶体的形式从水中析出,提纯简单,性质稳定.通过DTCD与偶氮二异丁腈(AIBN)或偶氮二氰基戊酸(ACVA)的反应合成了2种性能优异的叔丁腈酯基RAFT试剂,N-咔唑二硫代甲酸异丁腈酯(CYCBD)和N-咔唑二硫代甲酸氰基戊酸(CVCBD),新合成工艺的副反应和杂质被大量减少,最终产物的收率可达80%以上.以CYCBD和CVCBD为可逆加成断裂链转移(RAFT)试剂,研究了它们对甲基丙烯酸甲酯(MMA)RAFT聚合的控制能力,结果表明CYCBD和CVCBD是性能优异的RAFT试剂,可以很好地用于制备结构明确、分子量分布窄的链末端咔唑标记的聚甲基丙烯酸甲酯(CPMMA),由它们所制得的CPMMA的PDI小于1.2.研究结果还表明CYCBD和CVCBD及由其合成的CPMMA在四氢呋喃(THF)溶液中具有显著的荧光特性,CPMMA在358nm处有很强的荧光发射峰,而且,在浓度范围为0.1～20μmol/L的THF溶液中,CPMMA的荧光发射强度与其浓度具有良好的线性关系.通过CYCBD和CVCBD可以方便地制备结构明确且具荧光标识的功能聚合物。     

通过RAFT聚合制备SiO2/接枝共聚物纳米杂化粒子

以二氧化硅(SiO2)纳米粒子表面键接的二硫代苯甲酸酯作为可逆加成-断裂-链转移(RAFT)聚合反应的链转移剂, 在室温下引发苯乙烯和马来酸酐进行表面RAFT交替共聚反应, 制得了SiO2/苯乙烯-alt-马来酸酐杂化材料. 通过聚氧化乙烯(PEO)的羟基与马来酸酐的酯化反应, 将PEO接枝到SiO2纳米粒子的表面, 增加了硅粒子的生物相容性. 用FTIR, TGA和TEM对杂化材料的结构、组成和形貌进行了表征.     

SYNTHESIS AND CHARACTERIZATION OF HYPERBRANCHED VINYL POLYMERS FROM RAFT POLYMERIZATION OF AN ASYMMETRIC DIVINYL MONOMER

Hyperbranched vinyl polymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization of a styrenic asymmetric divinyl monomer.This was achieved by using cumyl dithiobenzoate or S-dodecyl-S′- (α,α′-dimethyl-α″-acetic acid)trithiocarbonate as the chain transfer agent,1,1′-azobis(cyclohexanecarbonitrile) or thermal initiation as a source of radicals.Cross-linking was inhibited by a rapid RAFT-based equilibrium between active propagation chains and dormant species,and thus a h...     

Synthesis of zwitterionic block copolymers via RAFT polymerization

A series of poly [2-(dimethylamino)ethyl methacrylate (DMA)-sodium acrylate (SA)] diblock copolymers were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization exhibits controlled characters: well-controlled molecular weight, narrow molecular weight distribution, molecular weight increasing with polymerization time. The zwitterionic diblock copolymers show rich solution behaviors. Dynamic light scattering (DLS) indicated the formation of micelles and reverse micelles of copolymers is affected by net charge density of copolymers. Microcalorimetry studies showed that the lower critical solution temperature (LCST) increases with incorporation of hydrophilic segments in buffer.     

二步法聚丙烯/丙烯酸表面接枝聚合研究

研究了二步法聚丙烯膜表面的丙烯酸接枝反应 .实验发现 ,以醋酐为溶剂的反应体系所得接枝率明显好于以水为溶剂的体系 ;接枝率随光敏剂浓度、单体浓度增大而增加 ;提高反应温度 ,可使接枝率明显增大 ;接枝后的聚丙烯膜表面亲水性可明显改善 .并用红外光谱证实了丙烯酸在聚丙烯膜表面的接枝 .     

RAFT mediated polysaccharide copolymers

Graft copolymers were prepared using the RAFT process via a Z-group approach, where xanthate esters were formed directly on a cellulosic substrate. Grafting of vinyl acetate onto the modified cellulosic materials was then carried out via the reversible addition fragmentation chain transfer (RAFT) process. The xanthate RAFT agents on the backbone of the cellulosic materials were identified by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet-visible spectroscopy (UV-vis). The number average molar masses of the graft copolymers were determined using size exclusion chromatography (SEC) and further characterization was conducted via liquid adsorption chromatography (LAC). The chromatographic results showed that the modified cellulosic materials were successfully grafted with polyvinyl acetate in a controlled manner. Grafted polyvinyl acetate (on the surface) and nongrafted polyvinyl acetate (in the solution) have almost the same molar mass and polydispersity index.     

紫外光引发聚乙二醇二甲基丙烯酸酯的RAFT交联聚合研究

合成了S-1-十二烷基-S′-(α,α′-二甲基-α″-乙酸)三硫代碳酸酯(TTC),以此为链转移剂,采用光差动热分析仪(DPC)和动态力学分析(DMA)方法研究了室温条件下紫外光引发的聚乙二醇二甲基丙烯酸酯(PEGDMA)的可逆加成-断裂链转移(RAFT)自由基聚合行为.发现RAFT光聚合反应的反应速率小于常规自由基聚合,因为体系由扩散控制,反应中自加速趋势减缓.探讨了双键之间聚乙二醇链段长度对于聚合速率和最终转化率的影响.结果发现,随着中间聚乙二醇链段的增加,聚合速率先变小再变大,最终转化率缓慢变大.RAFT光交联产物的交联密度随中间链段长度的增加而下降,交联均匀性提高.     

MICRON CORE-SHELL PARTICLES PREPARED BY GRAFTING POLYMERIZATION OF METHYL METHACRYLATE FROM NARROW DISPERSE SURFACE OF CHLOROMETHYLATED POLYDIVINYLBENZENE VIA ATRP

Grafting of poly(methyl methacrylate) from narrow disperse polymer particles by surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) particles were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as the stabilizer. Chloromethylated PDVB was used as initiating core sites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system. It was found that poly(methyl methacrylate) was grafted not only from the particle surfaces but also from within a thin shell layer, leading to particles size increases from 2.38-3.00μm with a core-shell structure particles. The grafted core-shell particles were characterized with FTIR, SEM, DSC.     

纳米羟基磷灰石表面接枝聚合左旋丙交酯

为了改善HA纳米粒子与有机PLGA的相容性,分别采用六亚甲基二异氰酸酯加乙二醇、左旋乳酸改性纳米粒子表面后或直接原位接枝聚合左旋丙交酯等3种不同方法,制备了表面修饰聚乳酸的纳米羟基磷灰石(PLLA-g-HA).FTIR、XPS、TEM、TGA测试表明PLLA成功接枝到HA的表面.其中六亚甲基二异氰酸酯加乙二醇改性HA纳米粒子所获得的PLLA接枝率远高于其它两种方法达25%,调整有机相和无机相的比例对PLLA接枝率的影响较小,其在氯仿中可以稳定分散2天以上.共混电纺丝后的拉伸测试表明PLLA-g-HA/PLAG复合纤维膜的力学性能高于HA/PLGA膜,当两者之间的比例为5%拉伸性能达到最大值.     

水溶性RAFT链转移剂的制备及应用进展

可逆加成-断裂链转移(reversible addition-fragmentation chain transfer,RAFT)聚合是一种有效的可控/活性自由基聚合方法,在功能型高分子的制备中有广泛的应用,RAFT聚合的关键就在于选择合适的RAFT链转移剂。基于环保无害的要求,水溶性RAFT链转移剂的制备就至关重要。本文介绍了RAFT聚合的机理,综述了水溶性RAFT链转移剂的制备及应用进展,探讨出RAFT链转移剂水溶性的作用机理,一方面是极性基团的作用,另一方面是离子键氢键等的作用,这对水溶性RAFT链转移剂的制备有一定的启发。大分子RAFT链转移剂分子中常含有亲水基团和疏水基团,具有一定的分散作用,在水相条件下不仅可以通过扩链反应制备窄分子量分布的嵌段共聚物,还可以制备出微纳米凝胶。     

Synthesis and characterizations of 1,2,3-triazole containing polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization

A novel monomer containing triazole and naphthalene ring, 2-(1-naphthalen-1-ylmethyl-1H-[1,2,3]triazol-4-yl)-ethyl methacrylate (NTEMA), was designed and synthesized via “click” chemistry method. The RAFT polymerization of NTEMA was successfully carried out using 2-cyanoprop-2-yl dithiobenzoate (CPDB) as a RAFT agent, 2,2′-azobisisobutyronitrile (AIBN) as an initiator in tetrahydrofuran (THF) solution. The results showed that the polymerizations exhibited “living”/controlled characteristics. The obtained poly(2-(1-naphthalen-1-ylmethyl-1H-[1,2,3]triazol-4-yl)-ethyl methacrylate) homopolymers, PNTEMAs, were further coordinated with samarium ion to prepare rare earth containing polymers (PNTEMA-Sm(III) complexes) which were characterized by FT-IR, DSC and ICP-AES. The characterization data confirmed that triazole in side chain of the polymer could coordinate with Sm(III). The fluorescence property of the polymers and polymer Sm(III) complexes were investigated in solution and in film.