Dilute gelling systems: copolymers of styrene and glycol dimethacrylates

Gelation properties of the copolymers of styrene with various proportions of ¹⁴C labelled ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol (MW = 400) dimethacrylate have been studied. The thermal copolymerizations were carried out in 15% (v/v) solution in toluene. The rates of polymerization were found to increase with larger proportions of dimethacrylate cross-linking agents. The conversion at the gel point was surprisingly constant over a wide range of crosslinker concentration. The fraction of crosslinker saturated at both ends was found to increase in the order ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol 400 dimethacrylate. The proportion of completely reacted crosslinker increased only slowly with conversion. At very high concentrations of crosslinker, the onset of inhomogeneity was observed as described previously by Storey³ and Dusek¹⁸.     

Evaluation of the light polymerization efficiency of copolymers used in dental formulations by differential scanning calorimetry

Different compositions of visible‐light‐curable triethylene glycol dimethacrylate/bisglycidyl methacrylate copolymers used in dental resin formulations were prepared through copolymerization photoinitiated by a camphorquinone/ethyl 4‐dimethylaminobenzoate system irradiated with an Ultrablue IS light‐emitting diode. The obtained copolymers were evaluated with differential scanning calorimetry. From the data for the heat of polymerization, before and after light exposure, obtained from exothermic differential scanning calorimetry curves, the light polymerization efficiency or degree of conversion of double bonds was calculated. The glass‐transition temperature also was determined before and after photopolymerization. After the photopolymerization, the glass‐transition temperature was not well defined because of the breadth of the transition region associated with the properties of the photocured dimethacrylate. The glass‐transition temperature after photopolymerization was determined experimentally and compared with the values determined with the Fox equation. In all mixtures, the experimental value was lower than the calculated value. Scanning electron microscopy was used to analyze the morphological differences in the prepared copolymer structures. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Octadecyl acrylate - Methyl methacrylate block and gradient copolymers from ATRP: Comb-like stabilizers for the preparation of micro- and nano-particles of poly(methyl methacrylate) and poly(acrylonitrile) by non-aqueous dispersion polymerization

Three random and three block copolymers of methyl methacrylate (MMA) and octadecyl acrylate (ODA) were synthesized by atom transfer radical polymerization. These copolymers were assessed for their application as stabilizers in the one-step non-aqueous dispersion (NAD) polymerization of MMA and of acrylonitrile (AN) in a non-polar solvent mixture of hexane and dodecane. In all cases stable spherical micro-particle colloidal dispersions were formed with particle diameters in the range of 62-2725 nm for PMMA. Uniform monodisperse PMMA particles with standard deviations in size distributions of less than 5% were obtained in two cases demonstrating the utility of ODA:MMA copolymers as replacement preformed stabilizers in the one-step synthesis of MMA micro-spheres. Overall the block copolymer PMMA₆₄-block-PODA₃₆ gave greater control over size when varying the solvent:monomer ration than a related gradient PMMA-PODA copolymer. These copolymers were further used as stabilizers in the one-step NAD polymerization of MMA with ethylene glycol dimethacrylate (EGDMA) under similar conditions allowing for the preparation of monodisperse cross-linked PMMA particles with diameters ranging from 110 to 1700 nm. The general utility of the copolymers as stabilizers was demonstrated by the NAD polymerization of acrylonitrile (AN) in non-polar solvent mixture of hexane and dodecane giving ‘crumpled’ latex dispersions with particle diameters in the range 85-483 nm.     

Porous polymer carbons. II. Preparation and properties of porous poly(vinylidene chloride) carbons

Suspension–polymerized copolymers of vinylidene chloride and ethylene glycol dimethacrylate have been converted into carbons by heating to 900°C. Poly(vinylidene chloride) homopolymer may melt on a first-stage heating at ca. 200°C and consequently yields a fused 900°C carbon; restraining the first-stage heating to slightly lower temperatures permits the retention of the polymer morphology which is then retained on subsequent carbonization at 900°C. The crosslinked copolymers do not fuse at 200°C and lose the dimethacrylate component, apparently cleanly, in the temperature range of 350–450°C and give 900°C carbons which are shrunken pseudomorphs of the parent polymer; all structural features are retained, including the characteristic skin of the polymer particles. Thus, the macroporous character of the carbons is controlled by both the crosslinker and diluent contents of the original polymerization recipe. The 900°C carbons are also microporous; hysteresis in nitrogen (77°K) isotherms is attributed to activated diffusion since carbon dioxide (196°K) isotherms are reversible. The microporosity of these dual-porosity carbons depends on the content of crosslinking comonomer in the parent polymer, and possible reasons for this dependence are discussed.     

丙烯酸系高吸油树脂的合成

采用悬浮聚合法，合成了低交联度的聚丙烯酸酯系的高吸油树脂，着重研究了引发剂和交联剂用量，聚合温度对吸油率和凝胶含量的影响。结果表明，交联剂影响最大，引发剂和温度的影响也不可忽视，在较佳的操作条件下，合成得甲苯吸收率高达２５克／克的高吸油树脂     

Synthesis and self-association in aqueous media of poly(ethylene oxide)/poly(ethyl glycidyl carbamate) amphiphilic block copolymers

New temperature sensitive AB, ABA, and BAB amphiphilic block copolymers consisting of hydrophilic poly(ethylene oxide) and hydrophobic poly(ethyl glycidyl carbamate) blocks were synthesized by anionic polymerization followed by chemical modification reactions. The self-association of the block copolymers in aqueous media was studied by UV-vis spectroscopy and dynamic and static light scattering. The obtained block copolymers spontaneously form micelles in aqueous media. The critical micellization concentration varied from 0.5 to 4 g/L depending on the copolymer architecture and composition. The influence of the temperature upon the self-association of the block copolymers was investigated. The increase of temperature did not affect the value of the critical micellization concentration, but led to the formation of better defined micelles with narrow size distribution.     

Reactive polymers,XXXVI. The effect of polymerization conditions on the porosity and mechanical properties of macroporous suspension copolymers from glycidylmethacrylate-ethylenedimethacrylate

By the method of design of experiments, the influence of the content and the thermodynamic quality of the mixture of inert solvents (porogenic compounds), of the concentration of the crosslinking agent and initiator in the polymerization mixture and of the reaction temperature in the radical suspension copolymerization was investigated with respect to the pore size, the porosity and the mechanical properties of macroporous copolymers from glycidylmethacrylate and ethylenedimethacrylate. It was found that the predominant effect on these characteristics should be attributed to the volume of the porogenic component in the mixture, and that the pore size and porosity increase at the same time the penetration modulus and the stress-at-break decrease proportionately to this volume. The concentration of the crosslinking agent has an influence only at low crosslinking values. The polymerization temperature and concentration of the initiator have only an insignificant effect on the structure and mechanical properties.     

Preparation of iodine containing quaternary amine methacrylate copolymers and their contact killing antimicrobial properties

A novel quaternary amine methacrylate monomer (QAMA) was synthesized by amination of dimethacrylate with piperazine followed by its quaternization using an alkyl iodide. Copolymerization of QAMA with 2‐hydroxyethyl methacrylate was carried out by free radical bulk polymerization technique at room temperature using ammonium persulfate and N,N,N′,N′‐tetramethyl ethylenediamine as a redox initiator. The monomer as well as copolymers was characterized by FTIR and ¹H NMR spectral studies. Thermal and physical characteristics of copolymers of varying compositions of QAMA were evaluated by thermogravimetric analysis, differential calorimetry, contact angle and scanning electron microscopy. The antibacterial activity of the synthesized quaternary amine dimethacrylate copolymers against Escherichia coli and Staphylococcus aureus was studied by zone of inhibition and colony count method. QAMA copolymers showed broad‐spectrum contact killing antibacterial properties without releasing any active agent as checked by iodide‐selective ion meter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1038–1044, 2006     

Frontal copolymerization of 2‐hydroxyethyl methacrylate and ethylene glycol dimethacrylate without porogen: comparison with suspension polymerization

Networked, crosslinked poly[(2‐hydroxyethyl methacrylate)‐co‐(ethylene glycol dimethacrylate)] (HEMA‐EGDM) was synthesized by frontal polymerization (FP) using azobisisobutyronitrile as initiator. HEMA‐EGDM copolymers of similar composition were also synthesized by suspension polymerization. The two sets of copolymers were characterized for functional groups (IR), pore volume (mercury intrusion porosimetry), surface area (nitrogen adsorption) and morphology (scanning electron microscopy). FP‐generated polymeric network structures had higher internal pore volumes and surface areas but their surface morphologies were inferior to those of copolymers synthesized by suspension polymerization. Copyright © 2004 Society of Chemical Industry     

丙烯酸改性聚醋酸乙烯酯乳液聚合的研究

通过丙烯酸与聚乙二醇共聚合成了具有反应活性的丙烯酸聚氧乙烯酯（简称大单体）,将大单体作为表面活性剂对醋酸乙烯酯乳液聚合的动力学进行了研究;同时在性能上与普通的乳液聚合体系进行了比较。实验结果表明聚合速率随亲水链长度、乳化剂浓度、引发剂浓度、温度的增大而增大,pH值的减小而加快,乳液性能也有了很大的改善．     

2‐Hydroxypropylmethacrylate based mono‐ and bifunctional gel beads prepared by suspension polymerization

Spherical and swellable gel beads in the size range 35–200 µm were prepared by suspension polymerization of 2‐hydroxypropylmethacrylate (HPMA). In the proposed method, a mixture of cyclohexanol and octanol was used as a diluent phase dispersed in an aqueous medium including poly(vinyl pyrrolidone) (PVP) as the stabilizer. The polymerization was initiated within the organic phase including the monomer and the crosslinker (ethylene glycol dimethacrylate) by an oil soluble initiator benzoyl peroxide. Spherical and swellable gel beads carrying both hydroxyl and carboxyl functional groups were also prepared by suspension copolymerization of HPMA and a water soluble comonomer (methacrylic acid). For this purpose, the suspension polymerization method proposed for HPMA was modified by using poly(vinyl alcohol) as a stabilizer instead of PVP. The effect of initiator concentration, polymerization temperature, monomer/diluent ratio, crosslinker concentration, stirring rate on yield, average size, size distribution, and carboxyl content of the HPMA based gel beads, were investigated. The swelling characteristics of the gel beads were defined. © 2000 Society of Chemical Industry     

Synthesis and nitrosation of processible copolymers from pyrrole and ethylaniline

A series of copolymers were prepared by an oxidative polymerization of pyrrole (PY) and 2-ethylaniline (EA) in HCl. The polymerization process was followed by tracking open-circuit potential and temperature of the reaction solutions. The fine particles of the PY/EA copolymers obtained in situ were further N-nitrosated for the first time in order to improve their solubility. The size, structure, and properties of the fine particles and their N-nitroso products were systematically characterized by laser particle size analyzer, FTIR, UV-vis, GPC, solution casting, and TG techniques. It is found that both the open-circuit potential and temperature of the solutions exhibit a maximum during the copolymerization, while the particle size of the copolymers will decrease monotonically with prolongating polymerization time or doping. Both the polymerization yield and molecular weight of the copolymers exhibit a minimum with PY/EA ratio, indicating a mutual retarding effect between the PY and EA monomers. The top potential and top temperature of the copolymerization as well as the particle size and its distribution, solubility, film-forming ability, electroconductivity, and thermostability of the copolymers all depend significantly on the PY/EA ratio. The PY/EA copolymers have good solubility in the solvents with the solubility parameter from 23 to 27 J^1/2/cm^3/2, dielectric constant greater than 12 and polarity index from 6.4 to 7.4 and their solubility becomes further better with increasing EA content. The N-nitrosation of copolymers can also improve their solubility in polar solvents furthermore. The copolymers with PY content of less than 30 mol% in NMP and THF exhibit good thin-film formability. The copolymer films become smoother and tougher with increasing EA content and by N-nitrosation. With increasing PY content, the decomposition temperature, maximum decomposition rate, char yield at 500 °C, and activation energy all decrease but decomposition order increases. The temperature at the maximum weight-loss rate of the copolymers has a maximum at the PY/EA molar ratio of 30/70. These results suggest that the polymer obtained is a real copolymer containing two comonomer units.     

Random copolymers based on trimethylene carbonate and ε‐caprolactone for implant applications: Synthesis and properties

Random copolymers of trimethylene carbonate (TMC) and ε‐caprolactone (CL) have been synthesized by ring‐opening polymerization of TMC and CL in the presence of stannous octoate. The effects of feeding dose, reaction temperature and polymerization time, and effect of catalyst content on the copolymerization were investigated. The results showed that the composition of the copolymers was in good agreement with the feeding dose, and the molecular weight of the copolymers decreased firstly with increasing CL content and then increased. The decrease in the reaction temperature, polymerization time and catalyst content would increase the molecular weight of the copolymers. Furthermore, the feeding dose affected the thermal and mechanical properties of the copolymer largely, and the possessing different properties of random copolymers could be obtained by adjusting the copolymer compositions. This work could optimize the polymerization conditions to achieve the copolymers with controlled properties for implant applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Anionic block copolymerization of cyclotetrasiloxanes initiated by p-bis(dimethyllithiioxysilyl)benzene

The triblock copolymers of poly(diphenyl-b-dimethyl-b-diphenyl)siloxane (PMP) and poly(diphenyl-b-dimethyl-co-methylvinyl-b-diphenyl)siloxane (PMVP) have been synthesized by the dianionic polymerization procedure. The polymerization of the cyclotetrasiloxane monomers initiated by lithium-based initiator has been carried out so as to avoid equilibration reactions. The new initiator, p-bis(dimethyllithiioxysilyl)benzene, was used. Dimethyl formamide (DMF) was used as a promotor. The effects of initiator concentration, polymerization temperature, and polymerization time on the reaction were investigated. The block copolymers have been determined by ¹H-NMR, infrared, ultraviolet, and differential scanning calorimetry. Progressive precipitation separation has been used to study the molecular weight distribution, and the integral distribution curves of the molecular weight have been given. © 1996 John Wiley & Sons, Inc.     

The effect of crosslinking agents on the copolymerization of styrene and n-butyl methacrylate

Summary The effect of low concentrations of multifunctional vinyl monomers acting as crosslinking agents, on the properties of poly(styrene-co-n-butyl methacrylates) with 30% wt of n-butyl methacrylate obtained by solution polymerization at a monomer conversion of approximately 60 wt % has been investigated. Ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,1,1-trimethylolpropane trimethacrylate and p-divinyl benzene were used as crosslinking agents. The relationship between the gel content, the relative viscosity increment, the weight-average molecular weight, non-uniformity, glass transition temperature, melting volume index and the concentration of the crosslinking agent was determined and discussed.     

Porous acrylonitrile/itaconic acid copolymers prepared by suspended emulsion polymerization

Porous acrylonitrile (AN)/itaconic acid (IA) copolymers were successfully prepared by suspended emulsion polymerization for the first time, with potassium peroxydisulfate (KPS) as an initiator, poly(vinyl alcohol) (PVA) as a dispersant agent, and Span80 as an emulsifier. The effects of the water/monomer mass ratio, agitation conditions, KPS concentration, PVA concentration, Span80 concentration,s and IA concentration on the average particle size and size distribution, particle morphology, and porosity of the AN/IA copolymers were investigated. The results show that the final AN/IA copolymers formed with agglomerates of primary particles had a porous structure, low particle density, and uniform particle size and did not agglomerate easily between the particles. The preparation conditions for the AN/IA copolymers were optimized as follows: (1) the water/monomer mass ratio was 0.3 : 1; (2) the concentrations of KPS, IA, PVA, and Span80 were 0.5, 12.4, 0.1, and 0.5 wt %, respectively, based on the weight of AN separately; (3) the agitation rate was 400 rpm; (4) the polymerization temperature was 70°C; and (5) the reaction time was 3 h. The size of the final AN/IA copolymer particles was in the range 200–400 μm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Simultaneous synthesis of dimethyl carbonate and ethylene glycol dimethacrylate using homogenous basic catalyst

A novel method simultaneously to prepare dimethyl carbonate and ethylene glycol dimethacrylate from ethylene carbonate and methyl methacrylate has been demonstrated in the presence of catalyst sodium methoxide and polymerization inhibitor ZJ-705. The effect of reaction parameters such as catalyst loading, polymerization inhibitor loading, concentration of reactants, reaction time, etc., on synthesis of dimethyl carbonate and ethylene glycol dimethacrylate was investigated. A reaction mechanism has been discussed with catalyst sodium methoxide.     

Controlling porous properties of polymer monoliths synthesized by photoinitiated polymerization

Porous monoliths have been successfully prepared by photoinitiated polymerization of hydroxyethyl methacrylate and ethylene glycol dimethacrylate monomers in a porogenic solvent. By varying the composition of the starting solutions such as initiator fraction, monomer ratio and pore generator (porogen) fraction and type, as well as UV intensity, monoliths have been obtained with narrow pore size distribution and median pore size from about a few nanometres to a few micrometres. © 2012 Society of Chemical Industry     

Diffusion coefficient of DMSO in polyacrylonitrile fiber formation

A H₂O/dimethyl sulfoxide(DMSO) mixture was used as the coagulation bath for the wet‐spun process of acrylonitrile/ammonium itaconate copolymers fibers. Diffusion coefficient of DMSO in the protofibers prepared by acrylonitrile/ammonium itaconate copolymers was determined. It has been found that diffusion coefficient of DMSO outflow of the protofibers prepared by acrylonitrile/ammonium itaconate copolymers synthesized by the solution polymerization is highest compared with those of acrylonitrile/ammonium itaconate copolymers synthesized by H₂O/DMSO mixture suspension polymerization and the aqueous suspension polymerization. With an increase of copolymer concentration in the dope, diffusion coefficient of DMSO decreases continuously. Diffusion coefficient of DMSO increases along with the bath temperature, but the changes of diffusion coefficient values are less prominent as temperature goes beyond 60°C. When DMSO concentration in the coagulation bath was 55 wt %, the value of the diffusion coefficient of DMSO was minimal. Diffusion coefficient of H₂O increases with the jet stretch minus ratio increasing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4447–4451, 2006