Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride) with styrene by ultrasonic irradiation

Summary The effect of several forms of suspension polymerized poly(vinyl chloride) particles on mechanochemical block copolymerization in the solid poly(vinyl chloride)-styrene-sodium dodecyl sulfate solutions has been studied by ultrasonic irradiation at 60 °C. The block copolymerization of styrene was initiated by free radicals produced from the poly(vinyl chloride) particles by ultrasonic waves. The rates of copolymerization increased with increasing the additional amount of the solid poly(vinyl chloride), the porosity, and the average diameter of the grain particles. In particular, the influence of the average diameter was much larger than that of the porosity. When the porosity and the average diameter were increased, the rates of decrease in the viscosity-average degree of polymerization of the degraded poly(vinyl chloride) were much increased. In addition, the changes in the composition of the block copolymer and homopolymers in the reaction products were obtained.     

Mechanochemical block copolymerization in heterogeneous systems of the solid polyethylene with acrylamide aqueous solutions by ultrasonic irradiation

Summary Mechanochemical block copolymerization in heterogeneous systems of the solid polyethylene-acrylamide-sodium dodecyl sulfate aqueous solutions has been studied by ultrasonic irradiation at 30 °C. An additional effect of the solid polyethylene and the effects of acrylamide, and sodium dodecyl sulfate concentrations on mechanochemical block copolymerization were investigated. The block copolymerization of acrylamide was initiated by free radical produced from the polyethylene particles by ultrasonic waves. The rate of copolymerization R _p increased with increasing additional amount of polyethylene and that value was of the order of 10^-3 mol/l s. In addition, the R _p was given by R _p [Acrylamide] [Sodium dodecyl sulfate].     

Mechanochemical block copolymerization of poly(vinyl chloride) with methyl methacrylate by ultrasonic irradiation

Summary Mechanical degradation and mechanochemical block copolymerization in systems of poly(vinyl chloride)-methyl methacrylate-solvents have been studied by ultrasonic irradiation at 60°C. The effect of the concentrations of poly(vinyl chloride) on mechanical degradation was investigated. In addition, the effects of poly(vinyl chloride) and methyl methacrylate concentrations on mechanochemical block copolymerization were investigated. The rate equation for mechanochemical block copolymerization has been deduced, and the experimental results were in fairly good agreement with the equation. The changes in the composition of the block copolymer and homopolymers in the reaction products were followed by turbidimetric titration.     

Mechanochemical synthesis and characterization of poly(vinyl chloride)-block-poly(vinyl alcohol) copolymers by ultrasonic irradiation

Mechanical degradation and mechanochemical reaction in heterogeneous systems of the solid poly(vinyl chloride)-poly(vinyl alcohol) aqueous solutions have been studied by ultrasonic irradiation at 30 °C. The rate of decrease in the viscosity-average degree of polymerization of the degraded poly(vinyl chloride) was much faster than that of the degraded poly(vinyl alcohol). Mechanochemical reaction occurred by free radicals produced from the chain scissions of both polymers by ultrasonic waves. The copolymer was obtained and the molar ratio of the vinyl chloride and the vinyl alcohol units in its copolymer can be determined. In addition, the changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(vinyl alcohol) were obtained. Received: 1 October 1998/Revised version: 9 January 1999/Accepted: 13 January 1999     

Mechanochemical synthesis and characterization of poly(vinyl chloride) -block- poly(acrylonitrile-co-butadiene) copolymers by ultrasonic irradiation

Summary Mechanical degradation and mechanochemical reaction in heterogeneous and homogeneous systems of poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer have been studied by ultrasonic irradiation at 30 °C. The rates of decrease in the number-average molecular weights of the degraded poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer in the swelled poly(vinyl chloride) — poly(acrylonitrile-co-butadiene) polymer solution were much faster than the homogeneous solution system and the final average chain lengths led to the smaller values than those in the latter system. On the other hand, mechanochemical reaction occurred by polymer radicals produced from the chain scissions of both polymers by ultrasonic irradiation. The changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(acrylonitrile-co-butadiene) polymer in both reaction systems were obtained. Received: 4 September 2001/Accepted: 22 October 2001     

Mechanochemical synthesis and characterization of poly(vinyl chloride)-block-poly(ethylene-co-propylene) copolymers by ultrasonic irradiation

Mechanical degradation and mechanochemical reaction in heterogeneous and homogeneous systems of poly(vinyl chloride) and poly(ethylene-co-propylene) polymer have been studied by ultrasonic irradiation at 30 °C. The rates of decrease in the number-average molecular weights of the degraded poly(vinyl chloride) and poly(ethylene-co-propylene) polymer were much faster in order of the solid poly(vinyl chloride)—poly(ethylene-co-propylene) polymer solution, the swelled poly(vinyl chloride)—poly(ethylene-co-propylene) polymer solution, and the homogeneous solution systems. On the other hand, mechanochemical reaction occurred by free radicals produced from the chain scissions of both polymers by ultrasonic waves. The changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(ethylene-co-propylene) polymer in individual reaction systems were obtained. In addition, the microscopic observation of the surfaces of the polymers on before and after mechanochemical reaction is carried out. Received: 10 May 2000/Revised version: 1 August 2000/Accepted: 3 August 2000     

Synthesis of poly[(2‐oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether‐co‐N‐phenylmaleimide] and its miscibility in blends with styrene‐acrylonitrile or poly(vinyl chloride)

The aim of the study was to investigate the synthesis of a copolymer bearing cyclic carbonate and its miscibility with styrene/acrylonitrile copolymer (SAN) or poly(vinyl chloride) (PVC). (2‐Oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether (OVE) as a monomer was synthesized from glycidyl vinyl ether and CO₂ using quaternary ammonium chloride salts as catalysts. The highest reaction rate was observed when tetraoctylammonium chloride (TOAC) was used as a catalyst. Even at the atmospheric pressure of CO₂, the yield of OVE using TOAC was above 80% after 6 h of reaction at 80°C. The copolymer of OVE and N‐phenylmaleimide (NPM) was prepared by radical copolymerization and was characterized by FTIR and ¹H‐NMR spectroscopies and differential scanning calorimetry (DSC). The monomer reactivity ratios were given as r₁ (OVE) = 0.53–0.57 and r₂ (NPM) = 2.23–2.24 in the copolymerization of OVE and NPM. The films of poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were cast from N‐dimethylformamide. An optical clarity test and DSC analysis showed that poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were both miscible over the whole composition range. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1809–1815, 2000     

Graft copolymerizaztion of methyl acrylate onto chitosan initiated by potassium diperiodatocuprate (III)

A novel redox system, potassium diperiodatocuprate [Cu (III)–chitosan], was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in alkali aqueous solution. The effects of reaction variables such as monomer concentration, initiator concentration, pH and temperature were investigated. By means of a series of copolymerization reactions, the grafting conditions were optimized. Cu (III)–chitosan system was found to be an efficient redox initiator for this graft copolymerization. The structures and the thermal stability of chitosan and chitosan‐g‐poly(methyl acrylate) (PMA) were characterized by infrared spectroscopy (IR) and thermogravimetric analysis (TGA). In this article, a mechanism is proposed to explain the formation of radicals and the initiation. Finally, the graft copolymer was used as the compatibilizer in blends of poly(vinyl chloride) (PVC) and chitosan. The scanning electron microscope (SEM) photographs and differential scanning calorimetry (DSC) thermograms indicate that the graft copolymer improved the compatibility of the blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2283–2289, 2003     

Synthesis of (AB)n-type block copolymers employing surface-active macro-azo initiators

A macro-azo initiator (MAI). prepared by polycondensation of azobiscyanopentanoyl chloride (ACPC) and polyethyleneglycol having average molecular weight of 1000 (PEG1000), was found to show enough surface activity to be usable as an initiator/surfactant (inisurf). Emulsion polymerization of styrene (St) using this MAI as inisurf was carried out and (AB)_n-type poly(PEO-b-PSt) block copolymer (where n represents the block-multiplicity) was obtained. In comparison with solution copolymerization, the emulsion block copolymerization gave PEO-b-PSt with higher molecular weight due to increased block multiplicity. © 1996 John Wiley & Sons, Inc.     

Copolymers of Diallyldimethylammonium Chloride and Vinyl Ether of Monoethanolamine: Synthesis,Flocculating, and Antimicrobial Properties

N,N-diallyl-N,N-dimethylammonium chloride (DADMAC) and vinyl ether of monoethanolamine (VEMEA) copolymer P(DADMAC-VEMEA) were synthesized using radical polymerization in water media using ammonium persulfate as an initiator. The synthesis of this copolymer was investigated over a wide composition range at low conversion levels. The viscosity of the copolymers was measured in aqueous 1 M NaCl. Flocculating action and antimicrobial activities of the copolymers P(DADMAC-VEMEA) against microbacteria and sulfate-reducing bacteria (SRB) were studied. Synthesized copolymers had flocculating effects and can be used to purify wastewater from particles of bentonite clays. Also, the copolymer with a molar composition [DADMAC]: [VEMEA] = (80÷20):(20÷80) retarded the population of both bacteria, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) in the diffusion zone. Furthermore, the copolymer with a molar composition [DADMAC]:[VEMEA] = (90÷10):(20÷80) had bactericidal properties against SRB. Minimum inhibitory concentration (MIC) of the copolymer varied from 0.01% to 0.1% depending on the molar composition of the copolymer.     

Poly(vinyl chloride)‐b‐poly(hydroxypropyl acrylate)‐b‐Poly(vinyl chloride): Understanding the synthesis of an amphiphilic PVC block copolymer on a pilot scale

The aim of this work was to develop an understanding of the major difficulties associated with the scale‐up of the technology for the synthesis of poly(vinyl chloride) (PVC) block copolymers that contain hydrophilic segments, thus providing important directions to be followed in order to produce such new materials on the industrial scale. The synthesis was carried out in a two‐step process. First, the macroinitiator α,ω‐di(iodo)poly(hydroxypropyl acrylate) was synthesized in an aqueous medium by (single electron transfer)/(degenerative chain transfer) living radical polymerization (SET‐DTRP) catalyzed by Na₂S₂O₄. The block copolymer was then prepared by SET‐DTRP of vinyl chloride (VC) from the iodine‐terminal active chain ends of the macroinitiator, thereby leading to the formation of the block copolymer poly(vinyl chloride)‐b‐poly(hydroxypropyl acrylate)‐b‐poly(vinyl chloride). This report covers important aspects related to the characterization of the block copolymer produced and to the identification of the major limitations that must be overcome in order to produce this new material on the industrial scale. The results clearly show the differences between the theoretical predictions and the block copolymer compositions obtained by using a suspension polymerization method, which is the most‐used polymerization process in the PVC industry. J. VINYL ADDIT. TECHNOL., 19:94–104, 2013. © 2013 Society of Plastics Engineers     

Graft copolymerzation of poly(vinyl chloride) with styrene. I. Synthesis and characterization

Graft copolymerization of poly(vinyl chloride) (PVC) partially dehydrochlorinated by heating in nitrobenzene was investigated using styrene as monomer and anhydrous AlCl₃ as cationic initiator in the temperature range of 0–35°C. Effect of monomer, catalyst, and PVC concentration on % graft-on was also evaluated. Introduction of labile sites in PVC by partial dehydrochlorination in nitrobenzene resulted in an increase in % graft-on. Intrinsic viscosity of PVC–g–polystyrene in THF initially increased with an increase in % graft-on. At higher % graft-on a decrease in [η] was observed.     

Synthesis and characterization of elastoplastic poly(styrene‐co‐ethylene) using novel mono(η5‐cyclopentadienyl) titanium and modified methylaluminoxane catalysts

Elastoplastic poly(styrene‐co‐ethylene) with high molecular weight was synthesized using novel mono(η⁵‐pentamethylcyclopentadienyl)tribenzyloxy titanium [Cp*Ti(OBz)₃] complex activated with four types of modified methylaluminoxanes (mMAO) containing different amounts of residual trimethylaluminum (TMA). The ideal mMAO, used as a cocatalyst for the copolymerization of styrene with ethylene, contains TMA approaching to 17.8 wt %. The oxidation states of the titanium‐active species in different Cp*Ti(OBz)₃/mMAO catalytic systems were determined by the redox titration method. The results show that both active species may exist in the current system, where one [Ti(IV)] gives a copolymer of styrene and ethylene, and the second one [Ti(III)] only produces syndiotactic polystyrene (sPS). Catalytic activity, compositions of copolymerization products, styrene incorporation, and copolymer microstructure depend on copolymerization conditions, including polymerization temperature, Al/Ti, molar ratio, and comonomers feed ratio. The copolymerization products were fractionated by successive solvent extractions with boiling butanone and tetrahydrofuran (THF). The copolymer, chiefly existing in THF‐soluble fractions, was confirmed by ¹³C‐NMR, GPC, DSC, and WAXD to be an elastoplastic copolymer with a single glass transition temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1851–1857, 1999     

Concentrated emulsion copolymerization of butyl acrylate and vinyl acetate initiated by a redox initiator at lower temperature

The concentrated emulsion copolymerization of butyl acrylate and vinyl acetate with an ammonium persulfate/sodium hydrogen sulfate mixture as a redox initiator, with a sodium dodecyl sulfate/cetyl alcohol mixture as a compound surfactant, and with poly(vinyl alcohol) as a liquid film reinforcer was carried out at lower temperature. In less than 3 h, the polymerization conversion was greater than 95%. The effects of the surfactant, the initiator, the volume fraction of the monomer, and the temperature on the stability of the concentrated emulsion, the kinetic process, and the average size of the latices were examined. The morphology of the polymer particles was observed by transmission electron microscopy, and the average size and distribution of the particle diameter were measured by photon correlation spectroscopy. The kinetic equation was R_p = k[M]^0.38[I]^0.89[E]^?0.80 at 30°C (where R_p is the polymerization rate, [I] is the initiator concentration, [M] is the monomer concentration, and [E] is the concentration of the compound surfactant), and the apparent activation energy was 22.69 kJ/mol. The thin‐layer polymerization of the concentrated emulsions, which enabled the removal of the heat of polymerization, was performed first. In comparison with test‐tube polymerization, thin‐layer polymerization provided a more regular morphology of the polymer particles. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 570–576, 2004     

Dynamic mechanical properties and morphology of styrene-divinylbenzene copolymer/poly(vinyl chloride) systems. (II). Effect of polymerization temperature

Effect of polymerization temperature on the phase-separated structure of the composite materials [P(St-DVB)/PVC systems] prepared by copolymerization of styrene (St) and divinylbenzene (DVB) in the presence of fine poly(vinyl chloride) (PVC) powder was studied by electron microscopy and dynamic mechanical test. P(St-DVB)/PVC systems have the two-phase nature with a styrene-divinylbenzene copolymer as the continuous phase [P(St-DVB) phase) and a PSt/PVC composite as the dispersed phase (PSt-PVC phase), in which PSt penetrates into the PVC domain. The crosslinking density of the P(St-DVB) phase is larger than that estimated from the recipe in the feed, suggesting that there exists a difference of the diffusion constants of styrene and divinylbenzene into the PVC particles on the paste formation and the polymerization process. The changes of the phase-separated structure of P(St-DVB)/PVC systems polymerized at various temperatures are also explained on the basis of the difference between the diffusion behavior of styrene and that of divinylbenzene into fine PVC particles at these temperatures.     

Synthesis of well‐defined polystyrene‐graft‐poly(methyl methacrylate)

A well‐defined graft copolymer, polystyrene‐graft‐poly(methyl methacrylate), was synthesized in two steps. In the first step, styrene and p‐vinyl benzene sulfonyl chloride were copolymerized via reversible addition–fragmentation chain transfer polymerization (RAFT) in benzene at 60 °C with 2‐(ethoxycarbonyl)prop‐2‐yl dithiobenzoate as a chain transfer agent and 2,2′‐azobis(isobutyronitrile) as an initiator. In the second step, poly[styrene‐co‐p‐(vinyl benzene sulfonyl chloride)] was used as a macroinitiator for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in toluene at 80 °C with CuCl as a catalyst and 2,2′‐bipyridine as a ligand. With sulfonyl chloride groups as the initiating sites for the ATRP of MMA, high initiation efficiencies were obtained. Copyright © 2006 Society of Chemical Industry     

Hyperbranched copolymers of p‐(chloromethyl)styrene and N‐cyclohexylmaleimide synthesized by atom transfer radical polymerization

The hyperbranched copolymers were obtained by the atom transfer radical copolymerization of p‐(chloromethyl)styrene (CMS) with N‐cyclohexylmaleimide (NCMI) catalyzed by CuCl/2,2′‐bipyridine (bpy) in cyclohexanone (C₆H₁₀O) or anisole (PhOCH₃) with CMS as the inimer. The influences of several factors, such as temperature, solvent, the concentration of CuCl and bpy, and monomer ratio, on the copolymerization were subsequently investigated. The apparent enthalpy of activation for the overall copolymerization was measured to be 37.2 kJ/mol. The fractional orders obtained in the copolymerization were approximately 0.843 and 0.447 for [CuCl]₀ and [bpy]₀, respectively. The monomer reactivity ratios were evaluated to be r_NCMI = 0.107 and r_CMS = 0.136. The glass transition temperature of the resultant hyperbranched copolymer increases with increasing f_NCMI, which indicates that the heat resistance of the copolymer has been improved by increasing NCMI. The prepared hyperbranched CMS/NCMI copolymers were used as macroinitiators for the solution polymerization of styrene to yield star‐shaped poly(CMS‐co‐NCMI)/polystyrene block copolymers by atom transfer radical polymerization. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1992–1997, 2000     

Processability and characterization of poly(vinyl chloride)‐b‐poly(n‐butyl acrylate)‐b‐poly(vinyl chloride) prepared by living radical polymerization of vinyl chloride. Comparison with a flexible commercial resin formulation prepared with PVC and dioctyl phthalate

This work reports the synthesis and processing of a new flexible material based on PVC produced by living radical polymerization. The synthesis was carried out in a two‐step process. In the first step the macroinitiator α, ω‐di(iodo)poly(butyl acrylate) [α, ω‐di(iodo)PBA] was synthesized in water by single electron transfer/degenerative chain transfer mediated living radical polymerization (SET‐DTLRP) catalyzed by Na₂S₂O₄. In the second step this macroinitiator was reinitiated by SET‐DTLRP of vinyl chloride (VC), thereby leading to the formation of the block copolymer poly(vinyl chloride)‐b‐poly(butyl acrylate)‐b‐poly(vinyl chloride) [PVC‐b‐PBA‐b‐PVC]. This new material was processed on a laboratory scale. The DMTA traces showed only a single glass transition temperature, thus indicating that no phase segregation was present. The copolymers were studied with regard to their processing, miscibility, and mechanical properties. The first comparison with commercial formulations made with PVC and dioctyl phthalate (DOP) is presented. J. VINYL ADDIT. TECHNOL., 12:156–165, 2006. © 2006 Society of Plastics Engineers     

Morphologies of polybutylacrylate/poly(styrene‐co‐methyl methacrylate) latex prepared by starved emulsion polymerization Part I. Thermodynamics equilibrium morphology

Heterogeneous latexes were prepared by a semicontinuous seeded emulsion polymerization process under monomer starved conditions at 80 °C using potassium persulfate as the initiator and sodium dodecyl sulfate as the emulsifier. Poly(butyl acrylate) latexes were used as seeds. The second‐stage polymer was poly(styrene‐co‐methyl methacrylate). By varying the amounts of methyl methacrylate (MMA) in the second‐stage copolymer, the polarity of the copolymer phase could be controlled. Phase separation towards the thermodynamic equilibrium morphology was accelerated either by ageing the composite latex at 80 °C or by adding a chain‐transfer agent during polymerization. The morphologies of the latex particles were examined by transmission electron microscopy (TEM). The morphology distributions of latex particles were described by a statistical method. It was found that the latex particles displayed different equilibrium morphologies depending on the composition of the second‐stage copolymers. This series of equilibrium morphologies of [poly(butyl acrylate)/poly(styrene‐co‐methyl methacrylate)] (PBA/P(St‐co‐MMA)) system provides experimental verification for quantitative simulation. Under limiting conditions, the equilibrium morphologies of PBA/P(St‐co‐MMA) were predicted according to the minimum surface free energy change principle. The particle morphology observed by TEM was in good agreement with the predictions of the thermodynamic model. Therefore, the morphology theory for homopolymer/homopolymer composite systems was extended to homopolymer/copolymer systems. © 2002 Society of Chemical Industry     

Study on preparation of monodispersed poly(styrene‐co‐N‐dimethylaminoethyl methacrylate) composite microspheres by SPG (Shirasu Porous Glass) emulsification technique

Monodispersed poly(styrene‐co‐N‐dimethylaminoethyl methacrylate) [P(St‐DMAEMA)] composite microspheres were prepared by employing a Shirasu Porous Glass (SPG) emulsification technique. A mixture of monomer, hexadecane (HD), and initiator N,N′‐azobis(2,4‐dimethylvaleronitrile) (ADVN) was used as a dispersed phase and an aqueous phase containing stabilizer [poly(vinyl pyrrolidone) (PVP) or poly(vinyl alcohol) (PVA)], sodium lauryl sulfate (SLS), and water‐soluble inhibitor [hydroquinone (HQ), diaminophenylene (DAP), or sodium nitrite (NaNO₂)], was used as a continuous phase. The dispersed phase was permeated through the uniform pores of SPG membrane into the continuous phase by a gas pressure to form the uniform droplets. Then, the droplets were polymerized at 70°C. The effects of inhibitor, stabilizer, ADVN, and DMAEMA on the secondary nucleation, DMAEMA fraction in the polymer, conversion, and morphologies of the particles were investigated. It was found that the secondary nucleation was prevented effectively in the presence of HQ or DAP when PVP was used as the stabilizer. The secondary particle was observed when ADVN amount was raised to 0.3 g (/18 g monomer); however, no secondary nucleation occurred even by increasing DMAEMA fraction to 10 wt %. This result implied that the diffusion of ADVN into the aqueous phase was a main factor responsible to the secondary nucleation more than that of DMAEMA. The hollow particles were obtained when NaNO₂ was used, while one‐hole particles formed in the other cases. By adding crosslinking agent, the hole disappeared and the monomer conversion was improved. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2408–2424, 2001