REVERSE ATOM TRANSFER RADICAL POLYMERIZATION OF STYRENE WITH COPPER-BASED CATALYST

'Living'/controlled radical polymerization of styrene was carried out with diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS)/CuCl2/bipyridine (bipy) initiation system at 120 degreesC. The molecular weights of resultant PSt increased with the monomer conversion and the polydispersities were in the range of 1.37 similar to1.52. A linear ln([M](o)/[M]) versus time plot was also obtained indicating the constant concentration of growing radicals during the polymerization with this initiation system. End group analysis by H-1-NMR spectroscopic studies showed that the end groups of the polymer obtained is omega -functionalized by a chlorine group from the catalyst and alpha -functionalized by a (carbethoxy-cyano-phenyl)methyl group from the fragments of the initiator. Having CI atom at the chain end, the PSt obtained can be used as a macroinitiator to promote a chain-extension reaction with fresh St and block copolymerization reaction with a second monomer, such as methyl methacrylate, in the presence of CuCl/bipy catalyst via a conventional ATRP process.

Atom Transfer Radical Polymerization of Methyl Methacrylate with α,α-Dichlorotoluene or α,α,α-Trichlorotoluene as Initiator

The atom transfer radical polymerization (ATRP) of methyl methacrylate using α.α dichlorotoluene or α.α.α-trichlorotoluene as the initiator and CuCl/2.2'-bipyridine complex as the catalyst was investigated. α,α-Dichlorotoluene gave good control of molecular weight with high initiation efficiency and low polydispersity. While α.α.α-trichlorotoluene gave very slow polymerization rate. which could be improved by the addition of Cu (0) to the system.

Synthesis of Comblike Poly(methyl methacrylate) by Atom Transfer Radical Polymerization with Poly(ethyl 2-bromoacrylate) as Macroinitiator

Comblike poly(methyl methacrylate) was synthesized by atom transfer radical polymerization of methyl methacrylate with poly(ethyl 2-bromoacrylate) as a macroinitiator, which was prepared by conventional free radical polymerization of ethyl 2-bromoacrylate. The obtained comblike polymers were characterized by GPC and 1H NMR.

N-Chlorosuccinimide （NCS）： A Novel Initiator for Atom Transfer Radical Polymerization of Methyl Methacrylate

Atom transfer radical polymerization （ATRP） of methyl methacrylate （MMA） was achieved, using N-chlorosuccinimide （NCS） as an initiator together with catalytic system CuCl/PMDETA （N,N,N＇,N＇,N＂-pentamethyldiethylenetriamine）, CuCl/MA5-DETA （N,N＇,N＇,N＂-penta（methylacrylate）diethylenetriamine）, and CuCl/bipy （bipy= 2,2＇-bipyridyl） respectively. The results indicated that the polymerization possessed typical controlled/living radical polymerization characteristics. The analysis for terminal group of obtained polymer by ^1H NMR proved that NCS is an initiator for ATRP. In comparison with NBS, the polymerization rate was slower and the resulted polymer had narrower molecular weight distribution （MWD） when NCS was employed as the initiator.

SYNTHESIS OF POLY(METHYL METHACRYLATE)-graft-POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by ~1H-NMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.

Reverse atom transfer radical polymerization of styrene in emulsion initiated by AIBN or V50

Reverse atom transfer radical polymerization of styrene was conducted in emulsion by using Cu(II)/2,2′- bipydine or Cu(II)/phen complexes, AIBN or V50 as the ini- tiator, Brij-98 or OP-10 as the surfactant. The results of GPC showed that both polymerization processes exhibit living characters when using AIBN as the initiator. However, when V50 was used, the monomer conversion was fairly low and the whole polymerization was not controlled well. The meas- urement of particle size and its distribution told us that the latex particles were mean and stable when using Brij-98 as the surfactant.

Graft Copolymerization of N,N-Dimethylacrylamide to Cellulose in Homogeneous Media Using Atom Transfer Radical Polymerization for Hemocompatibility

In homogeneous media, N,N-Dimethylacrylamide (DMA) was grafted copolymerization to cellulose by a metal-catalyzed atom transfer radical polymerization (ATRP) process. First, cellulose was dissolved in DMAc/LiCl system, and it reacted with 2-bromoisobutyloyl bromide (BiBBr) to produce macroinitiator (cell-BiB). Then DMA was polymerized to the cellulose backbone in a homogeneous DMSO solution in presence of the cell-BiB. Characterization with FT-IR, NMR, and GPC measurements showed that there obtained a graft copolymer with cellulose backbone and PDMA side chains (cell-PDMA) in well-defined structure. The proteins adsorption studies showed that the cellulose membranes modified by the as-prepared cell-PDMA copolymer owns good protein adsorption resistancet.

Grafting of 2-Hydroxyethyl Methacrylate onto Silk by Atom Transfer Radical Polymerization

Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyryl bromide(BriB-Br)to obtain efficient macroinitiator for ATRP.And the macroinitiator was grafted with HEMA in water aqueous using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine(PMDETA)as catalyst system.The effects of monomer concentration,the proportion of CuBr and PMDETA,grafting temperature and time on the silk grafting were discussed,and the optimal grafting technology was obtained.FT-IR characterization of the grafted silk showed a peak corresponding to HEMA,which indicated that HEMA was grafted onto the surface of silk.ATRP method could be applied on the silk modification and this technique provided a new way for silk grafting.

NEW INITIATION SYSTEMS FOR ATOM TRANSFER RADICAL POLYMERIZATION

This review summarizes our achievements in designing new initiation systems for atom transfer radical polymerization (ATRP). First-order kinetics and extension experiments revealed the living nature of these reactions. Tailor- made vinyl polymers with functional end groups were characterized by 1H-NMR and UV-vis spectroscopic analyses. Replacing traditional radical initiators AIBN and BPO, carbon-carbon bond compounds, 1,1,2,2-tetraphenyl-1,2-ethanediol, diethyl 2,3-dicyano-2,3-diphenylsuccinate and diethyl 2,3-dicyano-2,3-di(p-tolyl)succinate, were utilized in reverse ATRP to produce the initiating radical. Sulfur-sulfur bond iniferter, tetraethylthiuram disulfide (TD), in conjunction with CuBr/bpy or NiCl2/PPh3 complex could control the styrene polymerization via redox reaction. Pseudo-halogen transfer reaction was demonstrated to maintain the dormant-active species equilibrium in normal and reverse ATRP with Cu(S2CNEt2), Cu(S2CNEt2)Cl and Fe(S2CNEt2)3 as catalysts. The organic halide initiator and reduced transition metal compound that started the living polymerization were produced in situ from the components of TD/FeCl3/PPh3, TD/CuBr2/bpy and Fe(S2CNEt2)3/FeCl3/PPh3 systems. Accurate control of UV irradiation time favored the radical generation process in photo ATRP with the 2,2-dimethoxy-2-phenylacetophenone/Fe(S2CNEt2)3 initiation system.

NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)microspheres were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as stabilizer.The surfaces of PDVB microspheres werechloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzeneinitiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system.Polystyrene was found to begrafted not only from the particle surfaces but also from within a thin shell layer,resulting in the formation of particles sizeincreased from 2.38-2.58 μm,which can further grow to 2.93 μm during secondary grafting polymerization of styrene.Thisdemonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature.All of the preparedmicrospheres have narrow particle size distribution with coefficient of variation around 10%.

Water Repellent Finishing on Cotton Fabric via Atom Transfer Radical Polymerization

In order to enhance the water repellence property of cotton fabric, cotton fabric was grafted using hexafluorobutyl methacrylate( HFMT) monomer via atom transfer radical polymerization( ATRP) method. Water repellent cotton fabric was successfully prepared, and characterized by scanning electron microscopy( SEM),Fourier transform infrared spectroscopy( FTIR), and X-ray photoelectron spectroscopy( XPS). The SEM images of the HFMT-treated cotton displayed significant difference from the untreated one. FT-IR characterization of the HFMTtreated cotton indicated that HFMT was successfully grafted onto the surface of the cotton fabric. XPS analysis indicated that the fluorine element of the HFMT-treated cotton existing on the surface of the cotton fabric. The surface contact angle test as well as the water repellence rating test showed that the water repellence of the HFMTtreated cotton fabric was much better than that of the untreated cotton fabric. The surface contact angle of the HFMT-treated cotton fabric could reach( 132. 4 ± 2. 2) °,and the water repellence rating could achieve grade 3. The washing durability of the HFMT-treated fabric was also investigated. The surface contact angle of the HFMTtreated cotton fabric could reach( 121. 1 ± 2. 1) ° after 20 washing times. Furthermore, the whiteness, air permeability, breaking strength,and breaking elongation of the HFMT-treated cotton fabric decreased slightly compared with the untreated cotton fabric.Finally,cotton fabric with good water repellence property and excellent washing durability could be obtained with little effect on the intrinsic properties of cotton fabric.

Atom Transfer Radical Polymerization of Acrylonitrile in Ionic Liquids

The controllable molecular weight and polydispersity of polyacrylonitriles(PANs) were synthesized in ionic liquids(ILs) by atom transfer radical polymerization(ATRP) using ethyl-2 bromopropionate(EPN-Br) as initiator and CuBr/pentamethyldiethylenetria-mine(PMDETA) as catalyst.The polydispersity index(PDI) in the ATRP of acrylonitriel(AN) in ILs is lower than 1.3.From the polymerization kinetics,plots of ln([M]0/[M]) with time show a linear dependence at the early stage of polymerization while the deviation is observed with the conversion rate increasing.The polymerization rate in ILs,especially in 1-butyl-3-methylimidazolium chloride([bmim]Cl),is higher than that in N,N-dimethylformamide(DMF).The polymerization rate increased and the average molecular weight decreased with temperature increasing.The polymerization rate,molecular weight and PDI varied with the variation of [AN]0:[EPN-Br]0:[CuBr]0:[PMDETA]0 ratio in the experimental range,the polymerization of AN in [bmim]Cl displayed living polymerization characteristics.Moreover,the catalyst and ILs are easily isolated from the polymer and reused.

SYNTHESIS AND CHARACTERIZATION OF FOUR-ARMED BLOCK POLY(STYRENE-b-p-NITROPHENYL METHACRYLATE)PREPARED BY THE ATRP METHOD

A novel tetrafunctional initiator, C [CH_2O (CH_2)_3 OOCCH(Br)CH_3]_4 (1), was synthesized through the reaction oftetraol with α-bromopropionyl chloride, and then was used as initiator of atom transfer radical polymerization (ATRP) in thepreparation of 4-armed polystyrene (PSt) with narrow polydispersity. The structure, molecular weight and molecular weightdistribution (MWD) of each arm were studied by ~1H-NMR and GPC data of hydrolyzed products of the 4-armed PSt. TheATRP of St using 1/CuBr/bpy as initiator system is of 'living' character based on the following evidence: narrow MWD,constant concentration of chain radical during the polymerization, control of molecular weight by the molar ratio of monomerconsumed to 1. The 4-armed poly(St-b-p-nitrophenyl methacrylate) [poly(St-b-NPMA)] was prepared by the ATRP ofNPMA using 4-armed PSt with terminal bromine as the initiator, and characterized by FT-IR, ~1H-NMR spectra and GPCcurves. The micelles with PSt as core, and PNPMA as shell were formed by dropping DMSO into a solution of 4-armedpoly(St-b-NPMA) in DMF, as proved by laser light scatter (LLS) method.

Iron-mediated AGET ATRP of Styrene and Methyl Methacrylate Using Ascorbic Acid Sodium Salt as Reducing Agent

Atom transfer radical polymerization of styrene （St） and methyl methacrylate （MMA） in bulk and in different solvents using activators generated by electron transfer （AGET ATRP） were investigated in the presence of a limited amount of air using FeC13-6H2O as the catalyst, ascorbic acid sodium salt （AsAc-Na） as the reducing agent, and a cheap and commercially available tetrabutylammonium bromide （TBABr） as the ligand. It was found that polymerization in THF resulted in shorter induction period than that in bulk and in toluene for AGET ATRP of St, while referring to AGET ATRP of MMA, polymerization in THF showed three advantages compared with that in bulk and toluene：1） shortening the induction period, 2） enhancing the polymerization rate and 3） having better controllability. The living features of the obtained polymers were verified by chain end analysis and chain-extension experiments.

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 transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)particles were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as the stabilizer.Chloromethylated PDVB was used as initiating coresites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system.It was found that poly(methylmethacrylate)was grafted not only from the particle surfaces but also from within a thin shell layer,leading to particles sizeincreases from 2.38-3.00 μm with a core-shell structure particles.The grafted core-shell particles were characterized withFTIR,SEM,DSC.

A novel hydrophilic polystyrene-based beads for hydrophilic interaction chromatography by surface-initiated atom transfer radical polymerization

A one-step procedure to hydrophilize monodisperse poly（chloromethyl-styrene-co-divinylbenzene） beads has been presented with 2-hydroxy-3-[4-（hydroxymethyl）-1H-1,2,3-triazol-1-yl]propy1 2-methylacrylate（HTMA） as monomer by surface-initiated atom transfer radical polymerization（SI-ATRP）.The length of the grafted poly（HTMA） chain was varied via controlling the ratio of HTMA to initiator on the surface of the beads.Using these grafted beads as the stationary phase in hydrophilic interaction chromatography,good separation was obtained for nucleosides in the mobile phase of acetonitrile-water.It was also found that the retention time and selectivity of solutes showed a positive relationship with the length of the grafted poly（HTMA） chain.

原子转移自由基聚合(ATRP)在星形聚合物合成中的应用

综述了近10年来采用原子转移自由基聚合(ATRP)法合成星形聚合物的研究进展。从聚合单体、引发剂、聚合方法和反应条件以及聚合物性质等方面讨论了原子转移自由基聚合在星形聚合物合成中的应用,并根据聚合方法和引发剂对各种反应进行了分类。对原子转移自由基聚合技术在合成功能性复杂星形聚合物中的应用进行了展望。

用ATRP法构筑核壳型梯度极性的多羟基多臂星状超支化聚合物及聚合物刷——双层聚合物刷的合成与表征

设计并通过原子转移自由基聚合方法 (ATRP)合成了核壳型多羟基多臂星状超支化聚合物刷 .以 2 溴异丁基酰溴封端的超支化聚 (3 乙基 3 羟甲基氧杂环丁烷 ) (HP Br)作为大分子引发剂 ,采用Cu(I)Br和N ,N ,N′ ,N′ ,N″ 五甲基二乙基三胺 (PMDETA)催化体系 ,在丁酮与丙醇的混和溶液中 ,通过甲基丙烯酸羟乙酯(HEMA)的ATRP溶液聚合 ,得到了一系列含有大量羟基的多臂星状超支化聚合物刷 (HP g PHEMA) ,并考察了其羟基的活性 ,发现羟基还可以与苯甲酰氯发生反应 .产物的结构和热性能用1 H NMR、FTIR、GPC、TGA、DSC等进行了表征和测试 .

ATRP与点击化学相结合制备环状聚甲基丙烯酸甲酯

An efficient route to macrocyclic polymers via “click” cyclization was presented.The α-bromine and ω-alkyne PMMA were prepared using the standard ATRP technique,initiated with propargyl 2-bromoisobutyrate,Cu(Ⅰ)Br and N,N,N’,N″,N-pentamethyldiethylenetriamine(PMDETA).Azidation of the terminal bromine was followed in DMF with sodium azide,and α-azide,ω-alkyne PMMA precursor was obtained.Then the “click” cylcization of precursor between terminal azide and alkyne was carried out under the catalysis of CuBr/PMDETA,during the course of the reaction,a pseudo-high dilution technique was utilized to ensure the favored intramolecular cylcization.The nearly complete cylcization has been confirmed by a combination of IR,1H NMR and GPC analysis,and cyclo-PMMA with an Mn of 15000,PDI of 1.38 was obtained.