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A new tetrafunctional initiator, di(hydroxyethyl)-2,9-dibromosebacate (DHEDBS) [HOCH 2 CH 2 OOCCHBr(CH 2 ) 6 CHBrCOOCH 2 CH 2 OH], was synthesized and used in preparation of A 2 B 2 miktoarm star copolymers, (polystyrene)2/ [poly(1,3-dioxepane)] 2 [S-(PSt) 2 (PDOP) 2 ], by transformation of atom transfer radical polymerization (ATRP) to cationic ring-opening polymerization (CROP). First, two-armed PSt with two primary hydroxyl groups sited at the center of macromolecule [(PStBr) 2 (OH) 2 ] was obtained by ATRP of St with the initiation system of DHEDBS/CuBr/bpy, and used as a chain-transfer agent in the CROP of DOP with triflic acid as the initiator. Therefore, A 2 B 2 miktoarm star copolymer S-(PSt) 2 (PDOP) 2 was formed. Its structure was confirmed by the 1 H NMR spectrum. Gel permeation chromatography (GPC) curves show that the polymers obtained have a relatively narrow molecular weight distribution. The hydrolysis product of S-(PSt) 2 (PDOP) 2 was also characterized by 1 H NMR and GPC.

The synthesis of A4B4 miktoarm star copolymers, where A is polytetrahydrofuran (PTHF) and B is polystyrene (PSt), was accomplished with orthogonal initiators and consecutive cationic ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). The compound formed in situ from the reaction of 3-{2,2-bis[2-bromo-2-(chlorocarbonyl) ethoxy] methyl-3-(2-chlorocarbonyl) ethoxy} propoxyl-2-bromopropanoyl chloride [C(CH2OCH2CHBrCOCl)4] with silver perchlorate was used to initiate the CROP of tetrahydrofuran. The obtained polymer contained four secondary bromine groups at the α position to the original initiator sites and was used to initiate the ATRP of styrene with a CuBr/2,2′-bipyridine catalyst to form a C(PTHF)4(PSt)4 miktoarm star copolymer. The miktoarm copolymer was characterized by gel permeation chromatography and 1H NMR. The macroinitiator C(PTHF)4Br4 was hydrolyzed to afford PTHF arms. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2134–2142, 2001

Soapless emulsion polymerization of n-butyl methacrylate (BMA) was carried out through microwave heating with potassium persulfate (KPS) as an initiator at 73 ± 2°C. The influence of the monomer amount, the initiator amount, and the addition of ethanol on the monomer conversion, the particle size, and its distribution were studied. The results indicate that microwave polymerization had a much higher rate and produced smaller particles with a slightly broader size distribution compared with normal polymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2455–2459, 2001

A novel hexafunctional discotic initiator, 2,3,6,7,11,12-hexakis(2-bromobutyryloxy)triphenylene (HBTP), was synthesized by the esterification of 2,3,6,7,11,12-hexahydroxytriphenylene with 2-bromobutyryl chloride. Atom transfer radical polymerizations of styrene, methyl acrylate, and n-butyl acrylate were carried out in 50 vol % tetrahydrofuran with HBTP/copper(I) bromide/2,2′-bipyridyl as an initiation system. The polymers produced had well-controlled molecular weights and narrow molecular weight distributions (

To clarify whether atom transfer radical polymerization can be extended to free radical ring-opening polymerization, the polymerization of 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) was carried out in the presence of ethyl α-bromobutyrate/CuBr/2,2‘-bipyridine. The structure of poly(BMDO) was characterized by 1H and 13C NMR spectroscopy as well as gel permeation chromatography. The living polymerization of BMDO was identified by the following facts: a straight line of ln([M]0/[M]) versus polymerization time, linear increase of molecular weight with increasing conversion, and narrowing polydispersity. The mechanism of living free radical ring-opening polymerization was discussed.

Poly(styrene-co-acrylonitrile) (P(St-co-AN)) microspheres were prepared by emulsifier-free emulsion copolymerization of styrene and acrylonitrile. Presence of cyano groups on the surface of these microspheres was confirmed by X-ray Photoelectron Spectroscopic analysis. By the method of chemical metal deposition, nickel particles were formed and deposited on the surface of microspheres to form polymer metal composite microspheres which showed magnetic properties. Transmission electron microscope observation showed that nickel particles of small size (15–50 nm) were attached and distributed over the surface of P(St-co-AN) microspheres. X-ray diffraction proved that the nickel particles were in zerovalent state.

The results of characterization had shown that it was [1+2] cycloaddition reaction when [60,70]fullerene reacted with 4,4,5,5-tetramethylidazoline-2-thione (1) and dl-valine by FT-IR, FD-mass, 1H NMR, 13C NMR, UV–Vis spectra. [60]fullerene reacting with 4,4,5,5-tetramethylidazoline-2-thione (1) and other α-aminoacids such as l-leucine and α-aminoisobutyric acid had been also done in order to understand the reaction better, and the possible mechanism was put forward based on the results of characterization. In this reaction, reaction temperature was very important due to the reactivity of different α-aminoacids and the result of the experiment had also shown that the reactivity of dl-valine was more reactive than that of other two α-aminoacids.

The living free radical ring-opening polymerization of 2-methylene-4-phenyl-1,3-dioxolane (MPDO) in the presence of ethyl α-bromobutyrate/CuBr/2,2'-bipyridine at various temperatures has been investigated. In comparison with the conventional ring-opening polymerization of MPDO, a lower content of ring-opened unit in the polymer was found. The results of ln[M] 0 /[M]) against polymerization time, (M n ) th and (M n ) NMR vs conversion, and GPC of the polymers are strongly indicative of the living polymerization process. Initiator efficiency was measured. The mechanism of polymerization, and the effect of pyridine on the polymerization mechanism were discussed.

1,3-Dioxepane was polymerized with triflic acid as an initiator in the presence of acetic acid (AA) and hexane diacid. The structure of the poly(1,3-dioxepane) (polyDOP) obtained was characterized by 1H NMR spectra and gel permeation chromatography. The molecular weights (MWs) were determined by vapor pressure osmometry. The results obtained in both systems were completely different from those in which low-MW polyols were used as chain-transfer agents. When the molar ratio of carboxylic acid to triflic acid was low, high-MW polyDOP with a controlled MW and narrow MW distribution was obtained. The content of the ester group in the final product depended greatly on the molar ratio of AA to triflic acid. The polymerization mechanism is discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1232–1240, 2000

Poly(styrene-co-methacrylic acid) P(St-co-MAA) microspheres with a monodisperse size distribution were prepared by emulsifier-free emulsion copolymerization of St and MAA. The effects of MAA content on the polymerization rate and the content of MAA in the copolymer were investigated by gravimetrical and IR methods, respectively. The results of XPS measurement indicated the presence of a carboxyl functional group. By chemical metal deposition, nickel or palladium particles were formed and deposited on the surface of P(St-co-MAA) microspheres to form P(St-co-MAA)Ni or P(St-co-MAA)Pd composite particles. XRD measurement and TEM observation confirmed that nickel and palladium metal particles in a small size (20–40 nm) were distributed on surface of the copolymer microspheres. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1693–1698, 2000

Styrene underwent the ATRP process using an asymmetric difunctional initiator, 2-hydroxylethyl 2′-bromobutyrate in combination with CuBr and 2,2′-bipyridine (bpy). Polystyrene with hydroxyl and bromine groups at each end of the polymer (HO-PSt-Br) was obtained, and used as a chain-transfer agent in the cationic ring-opening polymerization of 1,3-dioxepane with triflic acid as initiator. The structures of the polymerization products were analyzed by 1H NMR and GPC analyses, indicating the formation of block copolymer. The molecular weight distribution of the block copolymer was relatively narrow and the molecular weight of the polyDOP block was high. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 436–443, 2000

Polystyrene (PSt) with end-terminal bromine (Br-PSt-Br) was synthesized by the atom transfer radical polymerization of styrene with the difunctional initiator 1,2-bis(2′-bromobutyryloxy)ethane in combination with CuBr and bipyridine. The Br-PSt-Br reacted with silver perchlorate at −78 °C, and the resulting macromolecular initiator was used to initiate the polymerization of tetrahydrofuran. Triblock poly(tetrahydrofuran)-polystyrene-poly(tetrahydrofuran) (PTHF-PSt-PTHF) diol was obtained after propagation at −15 °C. The conversion of the polymerization was measured by gas chromatography. The structures of the triblock copolymer PTHF-PSt-PTHF diol were characterized by 1H NMR and gel permeation chromatography. The mechanism of cationic ring-opening polymerization is discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 337–344, 2000

A new spiro ortho carbonate, 3,9-di(p-methoxybenzyl)-1,5,7,11-tetra-oxaspiro(5,5)undecane was prepared by the reaction of 2-methoxybenzyl-1,3-propanediol with di(n-butyl)tin oxide, following with carbon disulfide. Its cationic polymerization was carried out in dichloromethane using BF3-OEt2 as catalyst. The [1H], [13C]NMR and IR data as well as elementary analysis of the polymers obtained indicated that it underwent double ring-opening polymerization. The polymerization mechanism is discussed. The curing reaction of bisphenol A type epoxy resin in the presence of the monomer and a curing agent was investigated. DSC measurements were used to follow the curing process. In the case of boron trifluoride-o-phenylenediamine (BF3-OPDA) as curing agent, two peaks were found on the DSC curves, one of which was attributed to the polymerization of the epoxy group, and the other to the copolymerization of the monomer with the isolated epoxy groups or homopolymerization. However, when BF3-H2NEt was used as curing agent, only one peak was present. IR measurement of the modified epoxy resin with various weight ratios of epoxy resin/monomer was performed in the presence of BF3-H2NEt as curing agent. The results demonstrate that the conversion of epoxy group increases as the content of monomer increases. The curing process and the structure of the epoxy resin network are discussed. © 2000 Society of Chemical Industry

Polymerizations of methylacrylate, styrene and methyl methacrylate were carried out in the presence dithiobenzoic acid (DTBA). The results exhibit controlled polymerization characters: well-controlled molecular weight, narrow molecular weight distribution (minimal value: 1.08), molecular weight linearly increasing with conversion and first-order kinetics of polymerization. The polymers were characterized by 1H NMR and GPC. The effect of temperature and molar ratio DTBA/AIBN on polymerization was investigated. A mechanism is proposed to explain the controlled polymerization characters. © 2000 Society of Chemical Industry

Emulsifier-free emulsion polymerization of styrene (St) and copolymerization of St and 4-vinyl pyridine (4VP) in the presence of ammonium persulfate were studied. A comparison between the two polymerization systems was made. It was found that there were big differences comparing polymerization rate, the number and size of the particles and distribution, and molecular weight. For the St–4VP system, it was found that the additional amount of 4VP influenced the copolymerization of St and 4VP, molecular weight, and particle size. The formation mechanism of the particles was discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1502–1507, 1999

The prepolymers were prepared by the reaction of 3,9-dihydroxyethyl-3′,9′-dibenzyltetraoxaspiro(5,5)undecane (2) with 4,4′-diphenylenemethane diisocyanate (MDI) or hexamethylene diisocyanate (HDI) for improving the properties of the epoxy resin. The volume changes of the curing system was measured. The effects of the prepolymers on the conversion of epoxy group and thermal stability of the epoxy resin were studied. Glass transition temperature (Tg) of the modified matrix slightly decreased as the content of the prepolymers in the resin system increased. Two peaks appeared on derivative thermal gravimetry (DTG) curves of the modified epoxy resin. The one at the lower temperature was due to the decomposition of the polymeric linkages produced from the prepolymers, the other belonged to the decomposition of epoxy resin. The thermal stability of the modified matrix decreased because of the prepolymers as modifiers. However, the residual carbon of the modified matrix had an increasing tendency with quantity of prepolymer added. The strength of the modified matrix slightly decreased, but the elongation increased. When the mixture of E-51, prepolymers and BF3-H2NEt were used as adhesives, the tensile strength and shear strength were improved. The factors influencing the adhesive strength were investigated

Polyimides were prepared from diamines: 2,4,6-trimethyl-1,3-phenylenediamine (3MPDA) and 2,3,4,5-tetramethyl-1,4-phenylenediamine (4MPDA). 1,4-Bis(3,4-dicarboxyphenoxy)benzene dianhydride (HQDPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3'-4,4'-diphenylsulphone tetracarboxylic dianhydride (SO(2)PDA), 3,3',4,4'-diphenylsulphide tetracarboxylic dianhydride (SPDA), pyromellitic dianhydride (PMDA), and 2,2'-bis(3,4-dicarboxyphenyl)hexa-fluoroisopropane dianhydride (6FDA) were used as dianhydride. The gas permeabilities of H-2, O-2 and N-2 through the polyimides were measured at temperatures from 30 degrees C to 90 degrees C. The results show that as methyl and trifluoromethyl substitution groups densities increase from 7.73 x 10(-3) molcm(-3) to 13.50 x 10(-3)molcm(-3), the peameability of H-2 increases 10-fold at 60% loss of permselectivity of H-2/N-2 however, the permeability of O-2 increases 20-fold at 20% loss of permselectivity of O-2/N-2. For O-2/N-2 separation, PMDA-3MPDA has similar performance to 6FDA-3MPDA and 6FDA-4MPDA; all have higher permeabilities for O-2 than normal polyimides, and the P(O-2)/alpha(O-2/N-2) trade-off relationships lie on the upper bound line for polymers. (C) 1999 Society of Chemical Industry.

Poly (1,3-dioxepane) [PDOP] triol was prepared by cationic ring-opening polymerization with [C 2 H 5 C(CH 2 OCH 2 CH 2 CO + ClO - 4 ) 3 ], trioxocarbenium perchlorate, as an initiator. The structures of the PDOP triols obtained were verified by 1 H-NMR, FTIR, and GPC results. Initiation, propagation, and termination mechanisms were discussed based on the structural analysis of the polyacetal polyols. The results of GPC, NMR, and IR measurements showed that the PDOP triols obtained had similar branch chain lengths. Number-average molecular weights were determined by vapor pressure osmometry (VPO), end group titration and 1 H-NMR.

New oxocarbenium perchlorates, [(C2H5)(4-n)C(CH2OCH2CH2CO+ClO)n, n = 3, 4] were synthesized and used in the preparation of poly (tetrahydrofuran) (PTHF) polyols. The structures of PTHF polyols and corresponding hydrolysis products were determined by 1H-NMR and FTIR. GPC curves showed that the amount of cyclic oligomers was negligible. The polymerization process was followed by gas chromatography. Kinetic studies showed no termination reaction. The mechanism of the polymerization was discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3391–3399, 1999

A series of copolyimides were prepared from 2,4,6-trimethyl-1,3-phenylenediamines (3MPDA), 3,3',4,4'-benzophenone tetracarboxyl dianhydride (BTDA), and pyromellitic dianhydride (PMDA). Modification of the copolyimides by ultraviolet irradiation were carried out. Gas permeabilities of H-2, O-2, and N-2 through the copolyimides and photochemically crosslinked copolyimides were measured at temperatures from 30 to 90 degrees C. The relationships between gas permeabilities and temperature are in agreement with the Arrhenius equation. The structure of photochemically crosslinked copolyimides were characterized by Fourier transform infrared and gel measurement methods. Linear relationships between both log P and E-p and the volume fraction of PMDA-3MPDA exist. Photochemically crosslinking modification result in a decrease in gas permeability and an increase in E-p and alpha(H-2/N-2) for all the copolyimides. For H-2/N-2 separation, photochemically crosslinked copolyimides are of higher gas permeabilities and permselectivities simultaneously than normal polyimides. (C) 1999 John Wiley & Sons, Inc.

A new four-armed poly(1,3-dioxepane) tetraol was prepared by cationic ring-opening polymerization of 1,3-dioxepane (DOP) in the presence of 6,6-bis(5-hydroxyl-2-oxapentyl)-4,8-dioxaundecanediol1,11 (THA) with triflic acid(I) as initiator. The structure of the poly(DOP) tetraol obtained was characterized by 1 H and 13 C NMR spectra. The molecular weights of the obtained tetraols were controlled by the mole ratio of DOP consumed to initial THA, and it was found that each macromolecule contains only one THA unit on the average. GPC studies showed that the cyclic oligomers in the products were negligible.

Monodispersed poly(styrene-co-4-vinylpyridine) [P(St-co-4VP)] microspheres were prepared by emulsifier-free emulsion polymerization. The chemical metal deposition was used to prepare magnetic P(St-co-4VP)Ni, and P(St-co-4VP)Co microspheres exhibited ferromagnetic properties. The morphology of P(St-co-4VP) and P(St-co-4VP)Ni or Co microspheres was studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electron spectroscopy for chemical analysis (ESCA) and XRD were used to investigate the valence changement of metals in air. The magnetic properties of the magnetic microsphere were studied. The difference of soft magnetism between P(St-co-4VP)Ni and P(St-co-4VP)Co microspheres was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2307–2312, 1998

Cationic polymerization of 1,3-dioxepane (DOP) initiated by triflic acid was carried out in the presence of 2,2-bis(hydroxymethyl)butanol (BHMB). The structure and molecular weight of the products were characterized by GPC and NMR spectra. The results showed that molecular weight of the polyacetal obtained could be controlled by the initial mole ratio of DOP/BHMB. GPC showed that as the mole ratio of BHMB/ DOP increased, the content of cyclic oligomers also increased. Proton, 13 C and 2D HMQC-fg NMR demonstrated that no hydroxymethyl group of BHMB appeared as an end group. It was also illustrated by proton NMR that some BHMB units existed in cyclic oligomers. The mechanism of formation of cyclic oligomers was discussed.

Copoly(PPO–THF) (oxypropane–tetrahydrofuran) diol and triol were synthesized by cationic copolymerization of PPO–THF in the presence of 1,4-butanediol (BD) or 2,2′-dihydroxymethyl butanol (DHMB). The results of proton nuclear magnetic resonance verified the chemical structure of the obtained diol and triol. The amounts of the end hydroxyl group for the obtained triol and diol were measured by the end group analysis method. Linear (B-series) and crosslinked (T-series) polyurethanes were prepared from the diol and triol, respectively. The weight ratio of hard segment in the soft domain was calculated with Fourier transform infrared spectroscopy. Differential scanning calorimetry technology was used to investigate the structure of hard domains in B- and T-series polyurethanes. Mechanical properties studies of B- and T-series polyurethanes were carried out. Higher ultimate strength of T-series polyurethane than that of the B-series one was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2163–2169, 1998

The cationic polymerization of 1,3-dioxepane (DOP) initiated with trifluoromethanesulfonic acid (I) in the presence of ethylene glycol (EG) was investigated. At sufficiently low concentration of the initiator ([I] > 0.01 mol/L vs. [EG] < 0.20 mol/L), the molecular weights of the obtained polyacetal oligodiols are controlled by the mole ratio of consumed DOP to initial EG. Gel-permeation chromatography studies revealed that the concentration of cyclic oligomers in the products are negligible. The mechanism of the polymerization was investigated by means of kinetic studies. The results showed that the polymerization proceeds according to the active chain end mechanism (ACF) in combination with the activated monomer mechanism (AM); thus the cyclic oligomer in the obtained polymer is reduced, and intermolecular chain transfer to EG in ACE is dominant. It was also demonstrated that as [DOP]2[I]/[EG] decreases the contribution of ACE to the polymerization decreases and that of AM increases. In addition, 1H and 13C NMR data illustrated that each macromolecule of polyDOP oligodiols contained one EG unit on average and that no EG end groups exist.

C 60 or C 70 reacts with 2-aminoisobutyric acid and cyclohexanone in chlorobenzene at refluxing through 1,3-dipolar cycloaddition to give [60]fulleropyrrolidine 1 or [70]fulleropyrrolidine 3 which can be oxidized with MCPBA at room temperature to yield stable nitroxides 2 or 4 . The compounds 1 and 3 were characterized by mass spectrum, FT-i.r., n.m.r. spectra. The compounds 2 and 4 were characterized by mass spectrum, FT-i.r., e.s.r. spectra. The magnetic properties of compounds 2 and 4 were measured by SQUID-magnetometer (MPMC Quantum Design), we found that they were paramagnetic.

A promising strategy is developed for synthesis of azide polymers by controlled/living free radical copolymerization of allyl azide in the presence of S-benzyl O-phenyl dithiocarbonate at 0 °C under 60Co γ-ray irradiation. Allyl azide can be markedly incorporated as a comonomer into the polymer chain in the process.

A versatile one-pot strategy for the preparation of reversibly cross-linked polymer-coated mesoporous silica nanoparticles (MSNs) via surface reversible addition-fragmentation chain transfer (RAFT) polymerization is presented for the first time in this paper. The less reactive monomer oligo(ethylene glycol) acrylate (OEGA) and the more reactive cross-linker N,N'-cystaminebismethacrylamide (CBMA) are chosen to be copolymerized on the external surfaces of RAFT agent-functionalized MSNs to form the cross-linked polymer shells. Owing to the reversible cleavage and restoration of disulfide bonds via reduction/oxidation reactions, the polymer shells can control the on/off switching of the nanopores and regulate the drug loading and release. The redox-responsive release of doxorubicin (DOX) from this drug carrier is realized. The protein adsorption, in vitro cytotoxicity assays, and endocytosis studies demonstrate that this biocompatible vehicle is a potential candidate for delivering drugs. It is expected that this versatile grafting strategy may help fabricate satisfying MSN-based drug delivery systems for clinical application.

Polymer dispersed liquid crystal (PDLC) materials based on poly(polyethyleneglycol methacrylate) are prepared by ultraviolet light induced polymerization. Microphase structure of PDLC films is observed by scanning electron microscopy. It reveals that reversed morphology type PDLC is obtained. The liquid crystal (LC) is a continuous phase and fills up the irregular space of the polymer network. A comprehensive investigation is performed on the electro‐optical properties of PDLC films. The light scattering and transmittance properties of PDLC films are studied. The effects of LC domain size, light wavelength, applied voltage, frequency, temperature, incident angle, and film thickness on electro‐optical properties of PDLC films are discussed. The results show that size and shape of LC domain seriously affect the electro‐optical properties of PDLC film.

Copolymerizations of 4-methylene-2-styryl-1,3-dioxolane (1) and 4-methylene-2-methyl-2-styryl-1,3-dioxolane (2) with electron-deficient monomers, such as maleic anhydride (MA) and acrylonitrile (AN) were investigated. Only homopolymer of 1 was obtained from the copolymerization of 1 with MA in the presence or absence of AIBN. The copolymerization of 1 and AN with AIBN as initiator gave a copolymer consisting of three kinds of repeating units. Reaction of 2 with MA gave a crystalline product with and without AIBN present. A nine-membered ring structure is proposed for this product based on its IR, UV, proton and 13 C-NMR spectra, as well as elemental analysis. No polymer was obtained from the copolymerization of 2 and AN with or without AIBN initiator. Based on the structures of the products obtained from the copolymerization, a number of polymerization mechanisms are proposed.

Silicone rubber particles with core–shell structure were prepared by polymerization of vinyl monomers in the presence of crosslinked and linear poly(dimethyl siloxane-methyl vinyl siloxane) latex. The monomers were added with either continuous or swelled-continuous addition mode. The core–shell morphology of silicone rubber/polystyrene [PST] and silicone rubber/poly(methyl methacrylate-divinyl benzene) [P(MMA-DVB)] composite particles were obtained. The effects of monomer addition mode, the compatibilities of the monomers or their homopolymer with silicone rubber, and the reactivity of polysiloxane with vinyl monomers on the formation of the core–shell structure were discussed. © 1996 John Wiley & Sons, Inc.

The polymer phosphine ligand with various crosslinkage and phosphine contents was prepared by copolymerization of diphenylvinyl-phosphine with divinylbenzene using 2,2′ -azobisisobutyronitrile (AIBN) as initiator. Linear methyl heptanoate in high yield was obtained from hexene-l catalyzed by polymer-supported and homogeneous phosphine-palladium-tin chloride complex. Comparison with the homogeneous catalyst, the polymer catalyst had higher activity and almost the same selectivity. The effects of the catalyst composition, the structure of the polymer ligand and other experimental variables on the catalytic activity and selectivity of the polymer catalyst have been examined, and are discussed in relation to the mode of this catalysis.

Silicone rubber particles with core-shell structure were prepared by polymerization of vinyl monomers in the presence of linear or cross-linked poly(dimethyl siloxane-methyl vinyl siloxane) latexes. The monomers were added in either continuous or swelled-continuous modes. Core-shell particles with poly(butyl methacrylate), or poly(methyl methacrylate), as the shell were obtained by using either addition mode. The core-shell structure was not observed for polysiloxane-polystyrene particles. The influence of monomer addition mode, the compatibilities of the monomers and their homopolymers with silicone rubber, and the reactivity ratios of the vinyl monomers with the vinyl group of linear polysiloxane particles, on the formation of the core-shell structure is discussed.

Rapid living free-radical polymerization of methyl acrylate under 60Co γ-ray irradiation in the presence of benzyl 1H-imidazole-1-carbodithioate at room temperature is reported. The results showed that the polymerization is a fast living process, and that the molecular weight of the polymer is as high as 39 600 g mol−1 at 68 % conversion with Mw/Mn = 1.09 within 68 min. The polymerization rate was markedly influenced by the structures of thiocarbonylthio compounds. Copyright © 2004 Society of Chemical Industry

Prepolymers were prepared by the reaction of 3,9-dihydroxyethyl-3',9'-dibenzyl-1,5,7,11-tetraoxaspiro(5,5)undecane with 4,4'-diphenylmethane diisocyanate (MDI) and 1,6-hexamethylene diisocyanate (HDI). The number-average molecular weights of the prepolymers can be controlled by changing the mole ratios of spiro compound and diisocyanates. Kinetic studies of the cure reaction for the epoxy resin system modified with or without prepolymers were followed by a HLX-1 dynamic torsional vibration apparatus. The results indicated that gel time (t g ) and activation energy (E a ) increased as the content of prepolymers in the epoxy resin system increased. A difference with the cure reaction of the pure epoxy resin, the second-order reaction for the epoxy resin modified with the prepolymers, was obtained. Rate constants (k) of the cure reaction are 0.231 min -1 for the epoxy resin, and 0.312 min -1 for the modified epoxy resin. The mechanism of the cure reaction was discussed.

A study on the increase of the flexibility and decrease of the internal stress of cured epoxy resins by addition of polysiloxane rubber particles grafted with and without glycidyl methacrylate (GMA) or methyl methacrylate (MMA) is reported. Polysiloxane latex was obtained by cycling a mixture of polysiloxane containing a vinyl group and aSiH group, respectively, emulsifier, and water in a homogenizer. Graft polymerization of GMA (or MMA) on these rubber particles was performed in the latex under γ-ray irradiation of 60Co. The rubber particles were used to improve the flexibility of the epoxy resin. The particles grafted with GMA showed a homogeneous distribution in the matrix, better inducing and terminating craze. Comparisons were made among the particles grafted with MMA and various MMAGMA or a series of GMA; the results indicated that the particles grafted with GMA (graft ratio = 10%) showed the greatest increase of elongation and decrease of internal stress. The factors influencing the toughness of the epoxy resin matrix are discussed. © 1995 John Wiley & Sons, Inc.

A new monomer, 2-methylene-7-oxabicyclo[2.2.1]heptane (IV) was synthesized via four steps. Its structure was confirmed by IR, 1H-NMR, and 13C-NMR spectra as well as elementary analysis. Free radical polymerization and copolymerization of IV were investigated. No homopolymer was obtained due to the effect of allyl inhibition. When IV copolymerized with electron-donor monomers, such as vinyl acetate and stvrene, IV acted as inhibitor for the polymerization of vinyl acetate, but could not inhibit the polymerization of styrene. However, the copolymers of IV with electron-accepting monomers, such as methyl methacrylate, acrylonitrile, or maleic anhydride (MA) were obtained. The contents of IV in the copolymers increased as e values of electron-accepting monomers increased. Strictly alternating copolymer was obtained only in the case of MA and IV. The thermal properties of copolymers were investigated. © 1995 John Wiley & Sons, Inc.

A one-stage method of preparing code–shell particles was developed for the system containing silicone oils and glycidle methacrylate (GMA). Although the formation of core–shell particles for the systems containing silicone oils and methyl methacrylate (MMA) or styrene (ST) is possible in view of thermodynamics, the core–shell particles were not obtained. Factors such as better compatibility of silicone oils with vinyl monomers, higher swelling degree of silicone rubber in the vinyl monomers, and larger addition rate of thevinyl monomers with Si—H during the crosslinking of silicone oil containing vinyl group and Si—H (SVB and SHB) do not favor the formation of core–shell particles. X-ray photoelectron spectrometer (ESCA) was used in determining the formation of core–shell particles. The mechanism of the formation of core–shell particles is discussed. © 1995 John Wiley & Sons, Inc.

Although photoluminescence of tertiary aliphatic amines has been extensively studied, the usage of this fundamental chromophore as a fluorescent probe for various applications has unfortunately not been realized because their uncommon fluorescence is easily quenched, and strong fluorescence has been observed only in vapor phase. The objective of this study is how to retain the strong fluorescence of tertiary amines in polymers. Tertiary amines as branching units of the hyperbranched poly(amine-ester) (HypET) display relatively strong fluorescence (Φ = 0.11-0.43). The linear polymers with tertiary amines in the backbone or as the side group are only very weakly fluorescent. The tertiary amine of HypET is easily oxidized under ambient conditions, and red-shifting of fluorescence for the oxidized products has been observed. The galactopyranose-modified HypET exhibits low cytotoxicity and bright cell imaging. Thus, this study opens a new route of synthesizing fluorescent materials for cell imaging, biosensing, and drug delivery.

Photo- and pH-responsive amphiphilic hyperbranched star copolymers, poly(6-O-methacryloyl-1,2;3,4-di-O-isopropylidene-d-galactopyranose)[poly(2-(N,N-dimethylaminoethyl) methacrylate)-co-poly(1'-(2-methacryloxyethyl)-3',3'-dimethyl-6-nitro-spiro(2H-1-benzo-pyran-2,2'-indoline))](n)s [HPMAlpGP(PDMAEMA-co-PSPMA)(n)], were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of the DMAEMA and the SPMA using hyperbranched PMAlpGP as a macro RAFT agent. In aqueous solution, the copolymers self-assembled to form core-shell micelles with HPMAlpGP core and PDMAEMA-co-PSPMA shell. The hydrophobic fluorescent dye nitrobenzoxadiazolyl derivative (NBD) was loaded into the spiropyran-containing micelles. The obtained micelles not only have the photochromic properties, but also modulate the fluorescence of NBD through fluorescence resonance energy transfer (FRET), which was also observed in living cells. Slight fluorescence intensity decrease of the spiropyran in merocyanine (ME) form was observed after five UV-visible light irradiation cycles. The cytotoxicity of the HPMAlpGP(PDMAEMA-co-PSPMA)(n) micelles was lower than that of 25k PEI. All the results revealed that these photoresponsive nanoparticles are a good candidate for cell imaging and may find broad applications in biological areas such as biological diagnosis, imaging, and detection.

A facile temperature induced self-assembly and self-crosslinking method has been developed for preparing bioreducible nanogels/microgels without need of any stabilizer, catalyst or additional crosslinking agent. The size of formed nanogels/microgels can be easily tuned via the polymer concentration.

A study of increasing the flexibility and lowering the internal stress of the cured epoxy resin was carried out by using polysiloxanes capped with functional groups and premaking polysiloxane particles with d= 1.1 μm and narrow distribution. Polysiloxanes capped with functional groups were prepared by the reaction of X-22-163B with bisphenol-A, hexanedioic acid, and decanedioic acid. Poly(dimethylsiloxane-b-arylester was synthesized by the reaction of poly(dimethylsiloxane) (X-22-162C) woth arylester oligomers

A number of linear and crosslinked polymer ligands containing P or N or S as coordinative atoms were prepared. The hydroformylation of olefins was carried out at mild conditions in the presence of complexes as catalysts which were made by complexation reactions of these ligands with various homogeneous complexes or metal salts. The obtained results were explained in terms of the influences of the polymer matrix, or the structures and compositions of the polymer chain, and the properties of polymer-metal complexes on activity and selectivity. The most important factor for enhancing the selectivity towards linear aldehyde lies in the properties of the polymer-metal complex. High selectivity up to 95% was obtained by using polymer phosphine ligand-Pt-Sn complexes as catalyst in the hydroformylation of olefins. The hydroformylation mechanisms were discussed.

A new unsaturated bicyclic ether, 2-methylene-7-oxabicyclo[2.2.1]heptane (4) was synthesized by successive Diels-Alder addition of furan to acrylonitrile, hydrogenation of cyano compound 5, and Hofmann degradation of the quaternary ammonium hydrate 7 derived from the amine 6. Cationic polymerization of the monomer 4 was carried out in CH2Cl2 using BF3 · OEt2, PF5, SbCl5 and SnCl4 as catalysts in the temperature range of −20 to −25°C. White or slightly yellow powdery polymers of low molecular weight were obtained with PF5 and BF3 · OEt2 as catalysts, while no polymer was obtained with SbCl5 and SnCl4 as initiators. The IR, 1H and 13C NMR spectra of the polymers indicated that they consist of three kinds of repeating units, that is, two unsaturated units caused by ring-opening polymerization and one addition unit. Using proton NMR data of the polymers, the distribution of repeating units was calculated. A polymerization mechanism is proposed. The thermal stability of the obtained polymers is discussed.

A direct access to photochromic polymeric vesicles was demonstrated via polymerization-induced self-assembly and reorganization (PISR). The resulting vesicles displayed interesting photochromic behaviors different from that of their free polymer chains in DMF, and the vesicles exhibited stronger fluorescence and excellent photostability due to confinement of conformational flexibility of the polymer chains in aggregates.

The hyperbranched poly(amido amine) nanoparticles (HPAMAM NPs) with multiple functions, such as biodegradability, autofluorescence, and specific affinity, were successfully prepared by Michael addition dispersion polymerization of CBA, AEPZ, and N-galactosamine hydrochloride (or N-glucosamine hydrochloride) in a mixture of methanol/water. The resultant NPs displayed strong photoluminescence, high photostability, broad absorption, and emission (from 430 to 620 nm) spectra. The fluorescence from HPAMAM NPs may be attributed to the tertiary amine chromophore. The incubation results of the liver cancer cells, HepG2, with the NPs showed that the NPs are nontoxic and can be recognized by asialoglycoprotein receptors on the surface of HepG2 and then can be internalized. Therefore, they have potential applications in bioimaging and drug or gene delivery.