Radical/Cation Transformation Polymerization and Its Application to the Preparation of Block Copolymers

Propagating radicals could be transformed into corresponding cations in the radical polymerization process of vinyl monomers in the presence of an electron acceptor. The electron transfer reaction from the propagating radicals to the acceptor was confirmed by an electron spin resonance study and by the model compound reaction. The radical/cation transformation polymerization was effectively applied to the preparation of a new type of block copolymer compound of radically polymerized segments and cationically polymerized segments by the one shot method. Thus, a block copolymer of p-methoxystyrene (MOS) and cyclohexene oxide (CHO) was prepared by the radical polymerization of MOS in the presence of Ph₂I⁺PF⁻₆ and CHO. The formation of the block copolymer was confirmed by extraction separation, ¹H-NMR (nuclear magnetic resonance), thin layer chromatography and turbidimetric titration. © 1997 John Wiley & Sons, Ltd.     

用稳定自由基聚合及光引发聚合制备嵌段共聚物

介绍了稳定自由基聚合的反应原理、引发剂设计，以及用稳定自由基聚合制备嵌段共聚物的几种方法：连续加料法、双官能团引发剂法和一步法。对于光引发聚合的原理及硫自由基的稳定性对聚合反应的影响也进行了讨论。     

Synthesis of Dendritic-Linear Block Copolymers by Atom Transfer Radical Polymerization

Polymers and copolymers with complex, yet well-defined architectures are drawing significant attentions in the search for materials with excellent properties. Of these macromolecular structures, dendritic-linear block copolymers consisting of covalently bound linear and dendritic segments have shown interesting solution, solid-state, and interfacial properties. As a novel polymerization approach, atom transfer radical polymerization (ATRP) has been attracting increasing interest recently, sin…     

嵌段共聚物在乳液聚合和分散聚合中的应用

综述了嵌段共聚物在乳液聚合和分散聚合中作为稳定剂应用的进展，主要讨论了共聚物化学组成，比例，分子量，浓度以及胶束形成等因素对聚合体系的影响。     

Synthesis of Block Copolymers by Combination of Atom Transfer Radical Polymerization and Visible Light‐Induced Free Radical Promoted Cationic Polymerization

A new synthetic approach for the preparation of block copolymers by mechanistic transformation from atom transfer radical polymerization (ATRP) to visible light‐induced free radical promoted cationic polymerization is described. A series of halide end‐functionalized polystyrenes with different molecular weights synthesized by ATRP were utilized as macro‐coinitiators in dimanganese decacarbonyl [Mn₂(CO)₁₀] mediated free radical promoted cationic photopolymerization of cyclohexene oxide or isobutyl vinyl ether. Precursor polymers and corresponding block copolymers were characterized by spectral, chromatographic, and thermal analyses.     

Living Radical Polymerization in Homogeneous System by Using Iniferter: Design of Block Copolymers

Benzyl N-ethyldithiocarbamate(BEDC) and xylylene bis(N-ethyl-dithiocarbamate)(XEDC) were prepared, and used as mono- and bi-functional photoiniferters, respectively, of the polymerization of styrene and methyl methacrylate. These photopolymerizations were performed via a living radical polymerization mechanism in homogeneous system. The polymers obtained by BEDC and XEDC still contained one and two reactive N-ethyldithiocarbamate end groups, respectively, bonded at their chain ends. When these polymers were reacted with nucleophiles and copper(n) ion, the chain extension reactions were observed to occur depending on their functionality. By using the polymers obtained by BEDC and XEDC as mono- and bi-functional polymeric photoiniferters, the AB and ABA block copolymers were also obtained, respectively. Similar results were obtained by using benzyl N,N-diethyldithiocarbamate(BDC) and xylylene bis(N,N-diethyldithiocarbamate)(XEDC) as mono- and bifunctional photoiniferters, respectively. These results were also compared and discussed.     

Block Copolymers in Emulsion and Dispersion Polymerization

Summary: This article deals with recent progress including the authors' work concerning the application of block copolymers as polymeric surfactants in heterophase polymerizations. The synthesis methods for preparing block copolymers by emulsion and dispersion techniques are outlined, with emphasis on recently developed controlled free radical polymerizations in aqueous media. Specific characteristics of amphiphilic block copolymers are described, for example, micellization and emulsifying effects. A general overview of emulsion and dispersion polymerization in an aqueous and organic medium with ionic and nonionic block copolymers is presented for the preparation of electrosteric and sterically stabilized latex particles. Typical examples of microemulsion, miniemulsion, oil‐in‐oil emulsion, and micellar polymerizations are provided. Current and potential developments of so‐called “hairy latexes”, inverse‐, multiple‐, and solid emulsions, as well as of nonaqueous polymeric dispersions are also discussed.

PS foam obtained by free radical polymerization of water‐in‐styrene, stabilized with a PS–PEO diblock copolymer.     

原子转移自由基聚合法用于以单分散树脂为基质的强阳离子交换色谱固定相的制备及其色谱性能研究

以7μm单分散交联聚甲基丙烯酸环氧丙酯树脂表面键合溴异丁酰溴为引发剂,以CuCl/CuCl2/2,2-联二吡啶(Bpy)为催化体系,采用封闭体系,在氮气保护下,以乙烯基苯磺酸钠(NaSS)为单体、N,N-二甲基甲酰胺(DMF)水溶液为溶剂,制备了强阳离子交换色谱(SCX)固定相,并用元素分析与红外光谱法对其进行了表征....     

基于负离子-RAFT机理转换合成两亲性高度支化嵌段共聚物

报道了一种从引发型单体CX(inimer)出发、通过负离子-RAFT机理转换,制备两亲性高度支化聚合物的方法.首先,用仲丁基锂(s-Bu Li)与双官能团的1,1-二苯基乙烯衍生物MDDPE反应制备inimer,并通过inimer与苯乙烯共聚制备高度支化聚苯乙烯活性负离子;然后将末端负离子通过与CS2和1-溴乙基苯反应,原位转化为双硫酯基团,并作为大分子链转移剂(dendritic-CTA)调控N-异丙基丙烯酰胺(NIPAM)聚合,从而得到含聚苯乙烯(PS)和PNIPAM的两亲性支化嵌段共聚物.用联有光散射的凝聚色谱(GPC-MALLS)以及1H-NMR对产物进行了表征,并通过荧光探针、动态光散射(DLS)、透射电镜(TEM)等技术对两亲性支化嵌段共聚物在的溶液性质和乳化性能进行了研究.结果表明,该聚合物在水溶液中表现出独特的随温度变化的聚集行为,在水/油两相体系中具有极强的乳化能力.     

Tricyclopropylamine and Its Radical Cation

A surprisingly high first vertical ionization energy (8.44 eV) and an unusually high oxidation potential are exibited by tricyclopropylamine ( 1 )—in sharp contrast to triisopropylamine. These are attributed to the near-tetrahedral geometry of 1 at the N atom and the perpendicular orientation—with respect to the N-orbital axis—of the cyclopropyl groups. γ-Irradiation of 1 led to the radical cation 1 ^.+, which, in accord with computations, has a planar C_3h-symmetrical structure. The EPR-spectroscopic and computational results disclose a dramatic, previously not reported, conformational change on going from 1 to 1 ^.+.     

三嵌段共聚物PS-PHB-PS的原子转移自由基聚合

为了克服聚β-羟基丁酸酯(PHB)的弱点, 得到性能良好的新材料, 本文利用原子转移自由基聚合方法, 以Br-PHB-Br为大分子引发剂, 苯乙烯为单体, 在CuBr/N,N,N′,N″,N″-五甲基–二乙基三胺(PMDETA)催化体系作用下合成了一种新的三嵌段共聚物聚苯乙烯-聚β-羟基丁酸酯-聚苯乙烯(PS-PHB-PS). 共聚物的链结构利用¹H NMR和¹³C NMR进行了表征, 分子量特性和链段组成利用凝胶渗透色谱(SEC)方法进行了测定. 聚合物的分子量随单体转化率的增加而线性增加, 分子量分布指数相对较窄. 这些特征都满足原子转移自由基活性聚合的理想要求. 所得到的共聚物PS-PHB-PS具有较好的生物相容性, 与PHB相比具有良好的耐热性.     

Synthesis of Block Copolymers Modified with Phosphonate Ester Groups Using Nitroxide‐Mediated Radical Polymerization

Summary: Phosphonate groups were introduced into block copolymers of styrene derivatives either as single end‐groups or as small blocks using nitroxide‐mediated radical polymerization. In order to combine the hydrophobic and hydrophilic segments, block copolymers with N,N‐dimethyl acrylamide were synthesized. After hydrolysis to phosphonic acid groups, adsorption of the polymer onto metal oxides was possible.

Conversion of the phosphonate groups by transesterification with trimethylbromosilane (TMBS), followed by hydrolysis of the silylester group.     

烯烃易位聚合制备遥爪聚合物及嵌段共聚物

遥爪聚合物因其聚合物链的两端带有反应性官能团,可用于制备嵌段、接枝、星形、超支化等具有特殊结构的聚合物,其制备方法主要包括传统自由基聚合与可控/“活性”自由基聚合、阴离子聚合、阳离子聚合、易位聚合和缩合聚合等。相比于其他的传统聚合方法,烯烃易位聚合是一种较为温和的、产物分子量及结构可控的聚合方法。本文主要概述在各种链转移剂的存在下,采用环烯烃的开环易位聚合(ring-opening metathesis polymerization, ROMP)和非环二烯易位(acyclic diene metathesis, ADMET)聚合制备带有各种官能团的遥爪聚合物以及与其他活性聚合方法(NMRP、ATRP、RAFT、ROP等)相结合制备嵌段共聚物的研究进展。     

原子转移自由基聚合合成耐热性共聚物

自 1 995年第一篇有关过渡金属催化的原子转移自由基聚合 (ＡＴＲＰ)论文发表以来 ,国内外许多研究者都纷纷开展这方面的工作 ,人们已用该法合成了各类指定结构的聚合物[1～ 6] ,选用合适的引发剂比较容易合成出具有良好加工流动性的星型和超支化聚合物[2 ,3,6] .Ｎ 取代马来酰亚胺由于其环状结构而被广泛用于自由基共聚合制备耐热性聚合物[7～ 9] ,但Ｎ 取代马来酰亚胺的引入将降低聚合物的加工流动性 ,若能实现含Ｎ 取代马来酰亚胺单体结构的可控ＡＴＲＰ共聚合 ,利用多官能团引发剂如四溴甲基苯合成出星型耐热性共聚物 ,将可望同时改善聚…     

活性聚合法合成结构精确的含氟嵌段共聚物

结构精确的含氟嵌段共聚物具有优异而独特的化学和物理性能,有广阔的应用前景,因此受到广泛的关注.含氟嵌段共聚物可分为两类,一类是侧基含氟嵌段共聚物,另一类是主链含氟嵌段共聚物.活性聚合为嵌段共聚物的合成提供了最为重要的方法,利用它可以合成结构精确、分子量可控、分子量分布窄的嵌段共聚物.根据单体的反应特性选择不同的聚合方法,可以得到不同的含氟嵌段共聚物.本文主要综述了近几年利用各种活性聚合方法合成结构精确的含氟嵌段共聚物方面的进展.     

Supramolecular Polymerization of Polymeric Nanorods Mediated by Block Copolymers

Introducing a second component is an effective way to manipulate polymerization behavior. However, this phenomenon has rarely been observed in colloidal systems, such as polymeric nanoparticles. Here, we report the supramolecular polymerization of polymeric nanorods mediated by block copolymers. Experimental observations and simulation results illustrate that block copolymers surround the polymeric nanorods and mainly concentrate around the two ends, leaving the hydrophobic side regions exposed. These polymeric nanorods connect in a side-by-side manner through hydrophobic interactions to form bundles. As polymerization progresses, the block copolymers gradually deposit onto the bundles and finally assemble into helical nanopatterns on the outermost surface, which terminates the polymerization. It is anticipated that this work could offer inspiration for a general strategy of controllable supramolecular polymerization.     

New Segmented Copolymers by Combination of Atom Transfer Radical Polymerization and Ring Opening Polymerization

Atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP) were combined to synthesize various polymers with various structures and composition. Poly(ε-caprolactone)-b-poly(n-octadecyl methacrylate), PCL-PODMA, was prepared using both sequential and simultaneous polymerization methods. Kinetic studies on the simultaneous process were performed to adjust the rate of both polymerizations. The influence of tin(II) 2-ethylhexanoate on ATRP was investigated, which led to development of new initiation methods for ATRP, i.e., activators (re)generated by electron transfer (AGET and ARGET). Additionally, block copolymers with two crystalizable blocks, poly(ε-caprolactone)-b-poly(n-butyl acrylate)-b-poly(n-octadecyl methacrylate), PCL-PBA-PODMA, block copolymers for potential surfactant applications poly(ε-caprolactone)-b-poly(n-octadecyl methacrylate-co-dimethylaminoethyl methacrylate), PCL-P(ODMA-co-DMAEMA), and a macromolecular brush, poly(hydroxyethyl methacrylate)-graft-poly(ε-caprolactone), PHEMA-graft-PCL, were prepared using combination of ATRP and ROP.     

Combination of Episulfide Ring‐Opening Polymerization With ATRP for the Preparation of Amphiphilic Block Copolymers

We report for the first time the combination of ATRP and ring‐opening episulfide polymerization as a means to synthesize polysulfide‐based low‐dispersity amphiphilic block copolymers. The most significant finding is the possibility to perform ATRP under mild conditions using poly(propylene sulfide) macroinitiators, apparently without any significant copper sequestration by the polysulfides. Using glycerol monomethacrylate (GMMA) as a hydrophilic monomer, the polymers self‐assembled in colloidal structures with a morphology depending on the PS/GMMA ratio, but also probably on GMMA degree of polymerization. We here also present a new AFM‐based method to calculate the average number of amphiphilic macromolecules per micelle.     

RAFT聚合制备氟硅嵌段共聚物及结构性能

以三硫代酯封端的聚二甲基硅氧烷作为大分子链转移剂,通过可逆加成-断裂链转移聚合(RAFT)制备了一系列聚二甲基硅氧烷-b-聚甲基丙烯酸十二氟庚酯(PDMS-b-PDFHMA)二嵌段共聚物.利用凝胶渗透色谱(GPC)、傅里叶变换红外光谱(FT-IR)、氢核磁共振谱(1H-NMR)对该嵌段共聚物的组成、结构和分子量进行了表...