Controlled radical copolymerization of vinyl acetate and dibutyl maleate by iodine transfer radical polymerization

Iodine transfer radical homo‐ and copolymerization of vinyl acetate (VAc) with dibutyl maleate (DBM) were carried out in the presence of ethyl iodoacetate (EtIAc) and 2,2′‐azobis(isobutyronitrile) (AIBN) as chain transfer agent and initiator, respectively, at 60 °C. Molecular weight and its distribution and (co)polymer structure (i.e. copolymer composition and chain end groups) were analysed using gel permeation chromatography and ¹H NMR spectroscopy, respectively. Homo‐ and copolymerization reactions proceed via a controlled characteristic with predetermined molecular weight and relatively narrow molecular weight distribution. The presence of DBM in the reaction mixture decreases the consumption rate of EtIAc as well as the polymerization rate. This is attributed to the effect of DBM on the transfer constant to the EtIAc and probably on the iodine exchange rate constant between the growing chains. The effect of the concentration of AIBN, EtIAc and overall monomers on the conversion, molecular weight and its distribution was studied. Simultaneously high conversion and molecular weight with a relatively narrow molecular weight distribution can be achieved only when equimolar and intermediate concentration of EtIAc and AIBN is used in the reaction mixture. End‐group analysis by ¹H NMR reveals that iodinated VAc end groups in the (co)polymer chains are unstable, resulting in aldehyde end groups. Thermogravimetric analysis shows that the thermal stability of the VAc‐based polymer increases on incorporating DBM units into the copolymer chains. © 2013 Society of Chemical Industry     

Synthesis of random and block copolymers of vinyl chloride and vinyl acetate by RAFT miniemulsion polymerizations mediated by a fluorinated xanthate

Reversible addition–fragmentation chain transfer miniemulsion (co)polymerizations of vinyl acetate (VAc) and vinyl chloride (VC) are conducted in the presence of a fluorinated xthanate (X1). VAc miniemulsion polymerization can be well controlled by X1, and PVAc with small polydispersity index (PDI, <1.20) are obtained. X1 also shows well mediative effect to VC‐VAc miniemulsion copolymerization, while the PDI of VC‐VAc copolymer is greater than that of PVAc since a chain transfer rate to VC is greater than that to VAc. PVAc‐b‐PVC copolymers are synthesized by VC miniemulsion polymerizations mediated by X1‐terminated PVAc. PDIs of PVAc‐b‐PVC copolymers are greater than that of PVAc and VC‐VAc random copolymers with close monomer compositions, and increase with the increase of VC conversion. This is caused by the increased chain transfer to monomer and the formation of monomer‐rich and polymer‐rich phases during the VC polymerization stage. As‐prepared PVAc‐b‐PVC copolymers exhibit a micro‐phase separated morphology. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45074.     

(S)-2-(ethyl propionate)-(O-ethyl xanthate)- and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate)-mediated RAFT polymerization of vinyl acetate

(S)-2-(Ethyl propionate)-(O-ethyl xanthate) (X1) and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate) (X2) were used as the reversible addition-fragmentation chain transfer (RAFT) agents for the radical polymerization of vinyl acetate (VAc). The former showed the better chain transfer ability in the polymerization at 60°C. Kinetic study with both RAFT agents showed pseudo-first order kinetics up to around 85% monomer conversion. Molecular weight of the resulting polymer increased linearly with increase in the monomer conversion up to around 85%. The observed molecular weights calculated from ¹H-NMR spectrum [M_n(NMR)] are close to the corresponding theoretical molecular weights [M_n(theor)]. The corresponding polydispersity index (PDI) of the resulting polymers remained almost constant at around 1.2 up to ∼ 65% monomer conversion and then increased gradually with the further increase in the monomer conversion. Chain-end analysis of the resulting polymers by ¹H-NMR showed clearly that polymerization started with the radical forming out of the xanthate mediator. The negligible homo-chain extension and the hetero-chain extension involving synthesis of poly(VAc)-b-poly(NVP) diblock copolymer were occurred. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Morpholine‐based RAFT agents for the reversible deactivation radical polymerization of vinyl acetate and N‐vinylimidazole

Reversible addition–fragmentation chain transfer (RAFT) polymerization of less‐activated monomers in a controlled fashion is challenging due to the high reactivity and instability of the propagating radicals. We have designed dithiocarbamate‐based RAFT agents with morpholine as activating ‘Z’ group and benzyl, ethyl(1‐ethanoate)yl, ethyl(2‐propanoate)yl and cyanomethyl as ‘R’ leaving groups and investigated them for the reversible deactivation radical polymerization of vinyl acetate (VAc) and N‐vinylimidazole (N‐VIm). RAFT polymerization of VAc and N‐VIm at 70 °C using azobisisobutyronitrile as a free radical initiator proceeded in a controlled fashion as demonstrated by a linear increase in molar mass with conversion. Interestingly, the polymerization of VAc followed fast kinetics (approx. 60 min) with good to moderate control affording high‐molar‐mass poly(VAc) polymers. Furthermore, the synthesized chain transfer agents were able to polymerize N‐VIm under controlled conditions. The morpholine RAFT agents bearing cyanomethyl and ethyl(2‐propanoate)yl leaving groups showed better control of the polymerization of VAc and N‐VIm compared to the others. © 2020 Society of Chemical Industry     

Highly effective organometallic‐mediated radical polymerization of vinyl acetate using alumina‐supported Co(acac)2 catalyst: A case study of adsorption and polymerization

An alumina support system for cobalt^(II) acetylacetonate (Co(acac)₂) catalyst was studied for the cobalt‐mediated radical polymerization (CMRP) of vinyl acetate (VAc). We report a simple but efficient technique to produce this supported catalysts through the adsorption of Co(acac)₂ on the surface of alumina particles. Moreover, kinetic and thermodynamic study of Co(acac)₂ adsorption on the alumina support were conducted and the influence of effective parameters were investigated. It was found that using alumina‐supported Co(acac)₂ for radical polymerization of VAc yields polymers with controlled molecular weight, narrow molecular weight distribution, and high purity. For the alumina‐supported CMRP, changing the polymerization mechanism and domination of termination pathway compared to degenerate transfer pathway resulted in a 2.5 times increase in polymerization rate (k_ap) and a drop in induction time while maintaining a good control of the VAc polymerization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46057.     

Polyamide4‐block‐poly(vinyl acetate) via a polyamide4 azo macromolecular initiator: Thermal and mechanical behavior,biodegradation, and morphology

A series of polyamide4‐block‐poly(vinyl acetate)s were synthesized by the radical polymerization of vinyl acetate (VAc) using an azo macromolecular initiator composed of polyamide4 (PA4). The block copolymers were investigated by examining their molecular weight, structure, thermal and mechanical properties, biodegradation, and the morphology of the film surface. The compositions and molecular weights (Mw) ranging from 46,800 to 163,700 g mol^?1 of the block copolymers varied linearly with increasing molar ratio of VAc to azo‐PA4. The block copolymers have high melting points of 248.2–262.5°C owing to PA4 blocks and heats of fusion, which were linearly dependent on the PA4 content. The mechanical properties of the block copolymers were monotonically dependent on the composition, i.e., increasing the PA4 content increased the tensile strength, whereas increasing the poly(vinyl acetate) content increased the elongation at break. The morphology of the block copolymers suggested the appearance of microphase separation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42466.     

可逆加成-断裂链转移聚合制备聚氯乙烯-b-聚乙二醇-b-聚氯乙烯共聚物

合成了含黄原酸酯端基的聚乙二醇（X-PEG-X）大分子链转移剂,并以其为可逆加成-断裂链转移试剂调控氯乙烯（VC）溶液和悬浮聚合,合成聚氯乙烯-b-聚乙二醇-b-聚氯乙烯（PVC-b-PEG-b-PVC）三嵌段共聚物。X-PEG-X调控VC溶液聚合得到的共聚物的分子量随聚合时间增加而增大,分子量分布指数小于1.65。X-PEG-X具有水/油两相分配和可显著降低水/油界面张力的特性,以X-PEG-X为链转移剂和分散剂,通过自稳定悬浮聚合也可合成PVC-b-PEG-b-PVC共聚物,共聚物颗粒无皮膜结构,分子量随聚合时间增加而增大;由于VC悬浮聚合具有聚合物富相和单体富相两相聚合特性,共聚物分子量分布指数略大于溶液聚合共聚物。通过乙酸乙烯酯（VAc）扩链反应进一步证实了PVC-b-PEG-b-PVC的“活性”,并合成PVAc-b-PVC-b-PEG-b-PVC-b-PVAc共聚物。水接触角测试表明PVC-b-PEG-b-PVC的亲水性优于PVC。     

Atom transfer radical polymerization of methyl methacrylate initiated with a macroinitiator of poly(vinyl acetate)

Well‐defined poly(vinyl acetate‐b‐methyl methacrylate) block copolymers were successfully synthesized by the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in p‐xylene with CuBr as a catalyst, 2,2′‐bipyridine as a ligand, and trichloromethyl‐end‐grouped poly(vinyl acetate) (PVAc–CCl₃) as a macroinitiator that was prepared via the telomerization of vinyl acetate with chloroform as a telogen. The block copolymers were characterized with gel permeation chromatography, Fourier transform infrared, and ¹H‐NMR. The effects of the solvent and temperature on ATRP of MMA were studied. The control over a large range of molecular weights was investigated with a high [MMA]/[PVAc–CCl₃] ratio for potential industry applications. In addition, the mechanism of the polymerization was discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1089–1094, 2006     

Studies on the preparation of branched polymers from styrene and divinylbenzene

The self‐condensing vinyl polymerization of styrene and an inimer formed in situ by atom transfer radical addition from divinylbenzene and 2‐bromoisobutyl‐tert‐butyrate using atom transfer radical polymerization technique was studied. To study the polymerization mechanism and achieve high molecular weight polymer in a high polymer yield, the polymerization was carried out in bulk at 80°C. Proton nuclear magnetic resonance (¹H‐NMR) spectroscopy and gel permeation chromatography (GPC) coupled with multiangle laser light scattering (MALLS) were used to monitor the polymerization process and characterize the solid polymers. It is proved that the polymerization shows a “living” polymerization behavior and the crosslinking reaction has been restrained effectively due to the introduction of styrene. Polymers with high molecular weight (M_w.MALLS > 10⁵) can be prepared in high yield (near 80%). Comparison of the apparent molecular weights measured by GPC with the absolute values measured by MALLS indicates the existence of branched structures in the prepared polymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Novel micelle-forming block copolymer composed of poly (ε-caprolactone) and poly(vinyl pyrrolidone)

The well-defined poly (ε-caprolactone) (PCL)/poly(vinyl pyrrolidone) (PVP) diblock copolymers were synthesized through combining radical polymerization of VP and the controlled coordination-insertion ring-opening polymerization of CL using an aluminum alkoxide macroinitiator formed from the equimolar reaction of triethylaluminum with hydroxy-terminated PVP (PVP-OH). The molecular characterization of PCL/PVP diblock copolymers was confirmed through ¹H NMR spectroscopy and GPC analysis. Polymeric micelles composed of PCL as a hydrophobic core and PVP as a hydrophilic shell were prepared by a diafiltration method. The micellar properties such as sizes, shapes, and critical micelle concentrations (CMC) were investigated with a dynamic light scattering (DLS) spectrometer, transmission electron microscope (TEM) and spectrofluorimeter. The sizes of micelles ranged from 30 to 80 nm in average size. The novel micelles formed from the well-defined PCL/PVP diblock copolymers seem to be feasible as novel promising carriers in biomedical and pharmaceutical applications.     

Free radical copolymerization behavior of vinyl acetate with butyl acrylate in the presence of GeCl4 and BCl3

No alternating copolymers of vinyl acetate (VAc) and butyl acrylate (BA) were obtained by free radical copolymerization in the presence of GeCl₄ and BCl₃ (compared with the acrylic acid–vinyl acetate copolymerization system). By ultraviolet spectral analysis, it was concluded that both BCl₃ and GeCl₄ can form complexes with butyl acrylate. The BA–BCl₃ complex constants were determined by ¹H NMR; K_B=33·2 (25°C). The reason for the gel formation in the BA–Vac–BCl₃ copolymerization system was discussed. When vinyl acetate reacted with BCl₃, cationic polymerization probably occurred. A white gel product probably resulted from the polymerization of the BA–BCl₃ complex. © 1998 SCI.     

Synthesis and properties of polymer film modified electrodes to detect metal ions

In order to obtain modified polymeric electrodes, polymers were synthesized that are insoluble in water but soluble in common organic solvents and contain different functional groups that are able to coordinate metal ions from low concentrations. Poly(acrylic acid‐co‐styrene), poly(acrylamide‐co‐4‐vinyl pyridine), and poly(styrene‐co‐4‐vinyl pyridine) were synthesized by radical polymerization. The copolymers were characterized by FTIR, ¹H‐NMR, ¹³C‐NMR, scanning electron microscopy, and thermal analysis. The molecular weight and molecular weight distribution were determined by size exclusion chromatography. These complexing polymers were used in the preparation by spin coating of complexing chemically modified electrodes. The polymer film modified electrodes were then tested for the detection of metal ions using the chemical preconcentration and anodic stripping technique. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1192–1197, 2005     

Preparation of hyperbranched polymers through ATRP of in situ formed AB* monomer

The self‐condensing vinyl polymerization of an AB* monomer formed in situ by atom transfer radical addition from divinylbenzene (DVB) and (1‐bromoethyl)benzene (BEB) using atom transfer radical polymerization technique was studied. The catalyst concentration has a dramatic effect on polymerization. To study the polymerization mechanism and to achieve high molecular weight polymer, the polymerization was carried out in bulk with a catalyst to monomer ratio, 2,2′‐bipyridine to DVB, of 0.2 at 90°C. Proton nuclear magnetic resonance (¹H NMR) spectroscopy and size‐exclusion chromatography coupled with multiangle laser light scattering were used to analyze the polymerization aliquots and the obtained polymer. The intrinsic viscosities of the prepared polymers were also measured. Experimental results, from the comparison of the apparent molecular weights measured by size‐exclusion chromatography with the absolute values measured by multiangle laser light scattering as well as viscosity measurements, indicate the existence of hyperbranched structures in the prepared polymers. In sharp contrast to hyperbranched polymers from AB* monomer preprepared, hyperbranched ploy(divinylbenzene) prepared at equimolar amount of DVB and BEB has numerous residual pendant vinyl groups rather than only one double bond at its focal point. The hyperbranched polymers show relatively narrow molecular weight distribution (2.13–3.77) and exhibit excellent solubility in common organic solvents such as acetone. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 850–856, 2006     

Synthesis of high-molecular weight poly(vinyl alcohol) by low-temperature emulsifier-free emulsion polymerization of vinyl acetate and saponification

High-molecular weight (HMW) poly(vinyl alcohol) (PVA) was prepared via an emulsifier-free emulsion polymerization of vinyl acetate (VAc) using a redox initiation system in low temperatures, and the subsequent saponification with potassium hydroxide in methanol. The effect of the polymerization conditions on the conversion, molecular weight, and branching degree was investigated. PVA with maximum viscosity-average degree of polymerization (DP) of 8270 could be prepared by saponification of poly(vinyl acetate) (PVAc), with DP of 10,660 obtained at temperature of 10°C, monomer concentration of 30%, potassium persulfate molar ratio to monomer of 1/2000, agitation speed of 160 rpm. The conversion was above 90%. From the emulsifier-free emulsion polymerization of VAc in low temperature, PVAc with HMW and high linearity was effectively prepared, which might be useful for the preparation of high-strength and high-modulus PVA fiber. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Graft copolymerization of methyl methacrylate with an N‐substituted maleimide–liquid‐crystalline copolymer by atom transfer radical polymerization

The synthesis of novel copolymers consisting of a side‐group liquid‐crystalline backbone and poly (methyl methacrylate) grafts were realized by the use of atom transfer radical polymerization (ATRP). In the first stage, the bromine‐functional copolymers 6‐(4‐cyanobiphenyl‐4′‐oxy)hexyl acrylate and (2,5‐dioxo‐2,5‐dihydro‐1H‐pyrrole‐1‐yl)methyl 2‐bromopropanoate were synthesized by free‐radical polymerization. These copolymers were used as initiators in the ATRP of methyl methacrylate to yield graft copolymers. Both the macroinitiator and graft copolymers were characterized by ¹H‐NMR, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. The ATRP graft copolymerization was supported by an increase in the molecular weight of the graft copolymers compared to that of the macroinitiator and also by their monomodal molecular weight distribution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(vinyl chloride‐co‐vinyl acetate)‐graft‐poly[(meth)acrylates] by atom transfer radical polymerization

The graft polymerization of methyl methacrylate and butyl acrylate onto poly(vinyl chloride‐co‐vinyl acetate) with atom transfer radical polymerization (ATRP) was successfully carried out with copper(I) thiocyanate/N,N,N′,N′,N″‐pentamethyldiethylenetriamine and copper(I) chloride/2,2′‐bipyridine as catalysts in the solvent N,N‐dimethylformamide. For methyl methacrylate, a kinetic plot of ln([M]₀/[M]) (where [M]₀ is the initial monomer concentration and [M] is the monomer concentration) versus time for the graft polymerization was almost linear, and the molecular weight of the graft copolymer increased with increasing conversion, this being typical for ATRP. The formation of the graft polymer was confirmed with gel permeation chromatography, ¹H‐NMR, and Fourier transform infrared spectroscopy. The glass‐transition temperature of the copolymer increased with the concentration of methyl methacrylate. The graft copolymer was hydrolyzed, and its swelling capacity was measured. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 183–189, 2005     

Synthesis of end-group functionalized poly(octadecyl vinyl ether)

The cationic polymerization of octadecyl vinyl ether (ODVE) initiated by trimethylsilyl iodide and 1,1-diethoxyethane in the presence of ZnI₂ in toluene at 0°C and 10°C has been investigated. For molecular weights lower than 6000, a linearity of M̄_n with conversion was observed, but for higher molecular weights a strong deviation from calculated values, assuming a living mechanism, was found. Kinetic analysis of the polymerization and the variation of molecular weight as a function of conversion was in agreement with a transfer to monomer with k_tr/k_p ≌ 0.006 at 10°C. Analysis of the polymers obtained by termination with methanol provided evidence that the alkenyl ether end-groups formed by the transfer reaction lead to the same acetal end-groups as the active species. As a consequence, it is possible to prepare functionalized polyODVE polymers by end-capping with alcohols. This was confirmed by the synthesis of polyODVE macromonomers by end-capping with 2-hydroxyethyl methacrylate.     

Dispersion copolymerization of acrylonitrile‐vinyl acetate in supercritical carbon dioxide

Dispersion copolymerization of acrylonitrile‐vinyl acetate (AN‐VAc) had been successfully performed in supercritical carbon dioxide (ScCO₂) with 2,2‐azobisisobutyronitrile (AIBN) as a initiator and a series of lipophilic/CO₂‐philic diblock copolymers, such as poly(styrene‐r‐acrylonitrile)‐b‐poly(1,1,2,2‐tetrahydroperfluorooctyl methacrylate) (PSAN‐b‐PFOMA), as steric stabilizers. In dispersion copolymerization, poly(acrylonitrile‐r‐vinyl acetate) (PAVAc) was emulsified in ScCO₂ effectively using PSAN‐b‐PFOMA as a stabilizer. Compared with the precipitation polymerization (absence of stabilizer), the products prepared by dispersion polymerization possessed of higher yield and higher molecular weight. In addition, the particle morphology of precipitation polymerization was irregular, but the particle morphology of dispersion polymerization was uniform spherical particles. In this study, the effects of the initial concentrations of monomer and the stabilizer and the initiator, and the reaction pressure on the yield and the molecular weight and the resulting size and particle morphology of the colloidal particles were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5640–5648, 2006     

Syntheses,antitumour activities and antiangiogenesis of 1,2,3‐tris(ethoxycarbonyl)‐2‐propyl acrylate and its polymers

A new monomer, 1,2,3‐tris(ethoxycarbonyl)‐2‐propyl acrylate (TPA), was synthesized by reaction of acryloyl chloride and triethyl citrate. The homopolymer of TPA and its copolymers with acrylic acid (AA), vinyl acetate (VAc) and maleic anhydride (MAH) were prepared by polymerization using lauroyl peroxide (LPO) at 70 °C for 24 h. The structures of TPA and its polymers were identified by FTIR, ¹H NMR, ¹³C NMR spectroscopies, and elemental analysis. The number average molecular weights and polydispersity indices of the synthesized polymers determined by GPC were in the range 4200–23 000 g mol^?1 and 1.1–2.1, respectively. The IC₅₀ values of the synthesized samples against cancer cell lines were greater than those of 5‐fluorouracil (5‐FU). The percentage inhibition values of SV40 DNA replication were 82.2 for TPA, 34.3 for poly (TPA), 81.9 for poly(TPA‐co‐AA), 82.0 for poly(TPA‐co‐VAc), 35.6 for poly(TPA‐co‐MAH) and 12.7 for 5‐FU. The inhibitions of SV40 DNA replication and antiangiogenesis for the synthesized TPA and its polymers are much greater than those of the control. © 2001 Society of Chemical Industry     

Preparation and characterization of hyperbranched polyacrylate copolymers by self‐condensing vinyl copolymerization (SCVCP)

A series of hyperbranched polyacrylate copolymers have been synthesized by self‐condensing vinyl copolymerization (SCVCP) of 2‐(2‐bromopropionyloxy)‐ethyl acrylate (BPEA) and methyl acrylate (MA) in the presence of CuBr and bipyridine. The structures and properties of the polymers obtained are characterized by NMR and SEC/RALLS/DV/RI measurements. The effects of reaction conditions on molecular weight (MW), molecular weight distribution (MWD) and degree of branching (DB) are investigated. © 2002 Society of Chemical Industry