SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION(ATRP)

Alpha-trichloroacetoxy terminated polystyrene oligomer （PS-CH2CH2OCOCCl3） and poly-（styrene-b-butadiene）oligomer [P（S-b-B）-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 （PS-Cl3） or P（S-b-B）-CH2CH2O-COCCl3 （PSB-Cl3） was used as the macroinitiator in thepolymerization of （meth）acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared bythe integrated living anionic polymerization （LAP）-atom transfer radical polymerization （ATRP）. The structures of the PSB-Cl3 and the P（S-b-MMA） were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design blockcopolymers （the combination of LAP and ATRP） was developed.

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.

A FACILE APPROACH FOR THE SURFACE MODIFICATION OF POLY(VINYLIDENE FLUORIDE) MEMBRANE VIA SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

A novel approach for the surface modification of poly(vinylidene fluoride)(PVDF)membrane was successfully realized through alkaline treatment,UV-induced bromine addition,and followed by surface-initiated atom transfer radical polymerization(ATRP)of methyl methacrylate(MMA).Chemical changes on the PVDF membrane before and after modification were analyzed with attenuated total reflectance Fourier transform infrared spectroscopy(ATR/FT-IR)and X-ray photoelectron spectroscopy(XPS).Primary kinetic study revea...

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.

Kinetic Study of Atom Transfer Radical Polymerization of 2-(N,N-Dimethylamino)ethyl Methacrylate

A kinetic model was developed to describe the atom transfer radical polymerization (ATRP) of 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA). The model was based on a polymerization mechanism,which included the atom transfer equilibrium for primary radical, the propagation of growing polymer radical, and the atom transfer equilibrium for the growing polymer radical. An experiment was carried out to measure the conversion of monomer, the number-average molecular weight of polymer and molecular weight distribution for the ATRP process of DMAEMA. The experimental data were used to correlate the kinetic model and rate constants were obtained. The rate constants of activation and deactivation in the atom transfer equilibrium for primary radical are 1.0×10^4L·mol^-1·s^-1 and 0.04L·mol^-1·s^-1, respectively. The rate constant of the propagation of growing polymer radical is 8.50L·mol^-1·s^-1, and the rate constants of activation and deactivation in the atom transfer equilibrium for growing polymer radical are 0.045L·mol^-1·s^-1 and 1.2×10^5L·mol^-1·s^-1, respectively. The values of the rate constants represent the features of the ATRP process. The kinetic model was used to calculate the ATRP process of DMAEMA. The results show that the calculations agree well with the measurements.

Reverse Atom Transfer Radical Polymerization of (-)-Menthyl Methacrylate

The reverse atom transfer radical polymerization(RATRP) of (-)-menthyl methacrylate ((-)-MnMA) with AIBN(AIBN/CuCl2/bipyridine(bipy) or (-)sparteine((-)Sp) =1/2/4) initiating system in THF has been studied. The dependence of the specific rotation on molecular weight was investigated.

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.

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.

A NOVEL PHOTO-INITIATING SYSTEM FOR ATOM TRANSFER RADICAL POLYMERIZATION OF STYRENE

A novel photo-induced initiating system, 2,2-dimethoxy-2-phenylacetophenone (DMPA)/ferric tri(N,N-diethyldithiocarbamate) [Fe(DC)3], was developed and used for the atom transfer radical polymerization (ATRP) of styrene in toluene. The polymerization proceeds with DMPA as photo-initiator, Fe(DC)3 as catalyst and DC as a reversible transfer group, while the halogen and ligands are free. Well-defined PSt was prepared and the polymerization mechanism revealed by end group analysis belongs to a reverse ATRP. Block copolymer was prepared by using thus obtained PSt as macroinitiator and Fe(DC)2 as catalyst under UV light irradiation via a conventional ATRP process.

SYNTHESIS OF BLOCK COPOLYMER FROM 5,6 -BENZO-2-METHYLENE-1,3-DIOXEPANE AND METHYL ACRYLATE VIA ATOM TRANSFER RADICAL POLYMERIZATION

Poly(methyl acrylate)-b-poly(5,6-benzo-2-methylene-1,3-dioxepane) (PMA-b-PBMDO) was synthesized by twostep atom transfer radical polymerization (ATRP). Firstly, ATRP of methyl acrylate (MA) was realized using ethyl α-bromobutyrate (EBrB) as initiator in the presence of CuBr/2,2'-bipyridine. After isolation, poly(methyl acrylate) with terminal bromine (PMA-Br) was synthesized. Secondly, the resulting PMA-Br was used as a macromolecular initiator in the ATRP of BMDO. The structure of block copolymer was characterized by 1H-NMR spectroscopy. Molecular weight and molecular weight distribution were determined on a gel permeation chromatograph (GPC).

Synthesis of End Functional Polymers via Atom Transfer Radical Polymerization in Immobilized Catalytic System

Cross-linked polystyrene with azo-crown ether functional side chain (PSt-1, 10-dicarbonyl-3,6,9-trizaocylcodecane) was prepared under microwave irradiation and the structure was characterized through FT-IR and element analysis. The functionalized cross-linked polystyrene (cross-link degree, 3.5%) combining with immobilized catalyst system (CuBr and ethyl α-bromo-isobutyrate) can catalyze atom transfer radical polymerization of Styrene. Neat polymer products can be obtained then. Complex of La and the polymer end group (EBiB) was synthesized. The third order nonlinear optical property of the polymer-La complex was investigated and the structure was also characterized by FT-IR and XPS.

THERMOSENSITIVITY OF NARROW-DISPERSED POLY(N-n-PROPYLACRYLAMIDE)PREPARED BY ATOM TRANSFER RADICAL POLYMERIZATION

Controlled polymerization of N-n-propylacrylamide was achieved by atom transfer radical polymerization(ATRP) in a N,N-dimethylformamide-water mixture(50 vol%)at room temperature with methyl 2-chloropropinonate as initiator and CuCl/tris(2-dimethylaminoethyl)amine as the catalytic system in a ratio of 1:1:1.High molecular weight homopolymers(up to 3.7×10~4)with narrow molecular weight distribution(less than 1.2)were obtained.The living character of the polymerization was further demonstrated by self-block...

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

The dendritic polyarylether 2-bromoisobutyrate as the macromolecular initiator for the controlled free radical polymerization of styrene was investigated. The polymerization was carried out with CuBr/2,2’-bipyridine catalyst at 110℃. It is found that the hybrid dendritic-linear block copolymers possess well-defined molecular weights and low polydispersities.

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.

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 transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) microspheres were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as stabilizer. The surfaces of PDVB microspheres were chloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzene initiating core sites for subsequent ATRP grafting of styrene using CuC1/bpy as catalytic system. Polystyrene was found to be grafted not only from the particle surfaces but also from within a thin shell layer, resulting in the formation of particles size increased from 2.38-2.58 μm, which can further grow to 2.93 μm during secondary grafting polymerization of styrene. This demonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature. All of the prepared microspheres have narrow particle size distribution with coefficient of variation around 10%.

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.

ATOM TRANSFER RADICAL POLYMERIZATION OF 2,5-BIS[(4-HEXYLOXYPHENYL)OXYCARBONYL]STYRENE

A side-on liquid crystalline monomer, 2,5-bis[(4-hexyloxyphenyl)oxycarbonyl]styrene) (HPCS), was successfully polymerized via atom transfer radical polymerization (ATRP). The polymerization was catalyzed by CuBr/PMDETA in chlorobenzene at 90℃ with (1-bromoethyl)benzene as the initiator. The polymers have narrow MWD. It is the second example of mesogen-jacketed liquid crystalline polymer (MJLCP) prepared by ATRP.

Effect of catalyst on formation of poly(methyl methacrylate) brushes by surface initiated atom transfer radical polymerization

Poly(methyl methacrylate)(PMMA) brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization(SI-ATRP).Energy disperse spectroscopy(EDS) and atomic force microscopy(AFM) confirmed that PMMA brushes were successfully prepared on the silicon wafers,and the surface became more hydrophobic according to the contact angle of 69°.It is found that CuCl/1,1,4,7,10,10-hexamethyl triethylenetetramine(HMTETA) system is more suitable than CuBr/N,N,N′,N″,N″-pentamethyl diethylenetriamine(PMDETA) system to control the free radical polymerization of MMA in solution.Nevertheless,better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuCl/HMTETA due to higher activity and better reversibility of the former system.

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 atom complex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. The obtained 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 1HNMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-grafi-polystyrene. The molecular 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.