含N,N—二乙基二硫代氨基甲酸基的PVC引发苯乙烯接枝聚合的研究

本文介绍用铜试剂（Ｎ－Ｎ－二乙基二硫代氨基甲酸钠，简称ＮａＳＲ）取代ＰＶＣ中的部分氯原子，得到含有多个ＳＲ基团的功能高分子，并用它引发苯乙烯在四氢呋喃中的接枝聚合反应。结果表明，紫外光辐射下的单体转化率随单体浓度、引发剂浓度和聚时间的增加而增加，聚合反应具有高的接枝率和接枝效率，产物为交联聚合物。对照实验表明，在功能高分子存在下的热聚合或无功能高分子存在下的光聚合，其单体转化率都很低。     

Interpenetrating polymer networks. I. Photopolymerization of multiacrylate systems

The light-induced polymerization of a triacrylate monomer (TMPTA) has been carried out in a polymer matrix to generate a semi-interpenetrating polymer network (IPN). The reaction kinetics was followed by IR spectroscopy for the various polymer binders studied: poly(vinyl chloride) (PVC), poly(methyl methacrylate), polystyrene, and crosslinked polyurethane. Under intense illumination, crosslinking occurred extensively within a fraction of a second, with formation of a hard and highly resistant polymer material. These semi-IPNs were found to be essentially insoluble in the organic solvents, thus indicating that the acrylate network is grafted onto the polymer matrix, probably because of an efficient chain transfer process. The monomer and photoinitiator concentration, as well as the light intensity were shown to have a great influence on both the rate of polymerization and the final degree of conversion. By using an acylphosphine oxide photoinitiator, PVC–;TMPTA blends have been cured within a few minutes in an accelerated QUV-A weatherometer, which emits low-intensity UV radiation similar to sunlight. © 1994 John Wiley & Sons, Inc.     

On-line measurement of monomer concentration in UV photopolymerization using a quartz crystal resonator

In spite of the importance of monomer concentration measurement in polymerization, it is difficult to measure the concentration in thin film polymerization, such as the UV photopolymerization of acrylates. A small device, a quartz crystal resonator, has been applied to the measurement of monomer amount in the UV photopolymerization of trimethylolpropane triacrylate with an initiator of 2-ethylanthraquinone. The resonant resistance of the resonator is converted to the monomer concentration using an empirical relationship. The measurement results indicate that the proposed technique is effective for determining the monomer concentration. The simplicity and ready availability of the proposed application have been proven experimentally.     

UV‐radiation–induced preirradiation grafting of methyl methacrylate onto lignocellulose fiber in an aqueous medium and characterization

The preirradiation method of grafting has been established by ultraviolet radiation. Methyl methacrylate (MMA) was grafted onto jute fiber in an aqueous medium. The variation of graft weight with UV‐radiation time, monomer concentration, and reaction time was investigated. The conversion of monomer into homopolymer and graft copolymer was evaluated. The graft weight passes through a maximum value (～ 122%) with UV‐radiation time. The optimum value of the monomer concentration was evaluated for maximum degree of grafting. Graft copolymerization of MMA onto lignocellulose fiber significantly increases the elongation at break (～ 65%) compared to that of the “as‐received” sample. However, a linear decrease on breaking load was observed with the increase of graft weight. The estimation of degree of grafting was achieved using an IR technique by correlating band intensities with the degree of grafting. Considering the water‐absorption property, the grafted sample showed a maximum up to 61% decrease in hydrophilicity compared to that of the as‐received sample. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1667–1675, 2004     

ATR‐UV monitoring of methyl methacrylate miniemulsion polymerization for determination of monomer conversion

Attenuated Total Reflection (ATR) UV spectroscopy has been used to monitor monomer conversion in methyl methacrylate miniemulsion polymerization. It was found that the vinylic groups of methyl methacrylate strongly absorb the UV light with a maximum absorption at 225 nm. This absorption peak decreases as monomer is converted to polymer. The polymer has a strong absorption at a lower UV region. The results from this feasibility study indicate that ATR‐UV sensor technique has a great potential to be used for on‐line or in‐line process monitoring in emulsion and miniemulsion polymerization. With a partial least square (PLS) calibration model, very good prediction the monomer conversion was obtained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1471–1475, 2006     

紫外光引发甲基丙烯酸-N,N-二甲氨基乙酯溶液聚合的研究

研究了甲基丙烯酸 -N ,N -二甲氨基乙酯的紫外光引发自由基溶液聚合的条件 ,包括引发剂安息香乙醚用量、单体浓度、光引发时间及其对聚合速率、产率与相对分子质量的影响 ,实验确定了制备线型聚甲基丙烯酸 -N ,N -二甲氨基乙酯聚合物的工艺及方法。采用膨胀计法研究了聚合反应 ,其反应速率与单体浓度呈 1.91级关系 ,结果表明 ,单体可能同时参与了光引发过程     

Multiscale modeling of syndiospecific styrene polymerization

A detailed mathematical model for syndiospecific styrene polymerization based on combining features of the multigrain model (MGM) and the polymeric multigrain model (PMGM). This model has been established to predict the radial monomer concentration within the growing macro particles and the rate of polymerization. The latter, the parameters, have an effect on the molecular weight distribution (MWD). In this model, the effect of intraparticle diffusion resistance and the radius of catalyst particles on the rate of polymerization and MWD were studied. The model simulation showed the presence of a large distribution of monomer concentration across the radius of particles. It was further noticed that the diffusion resistance was most intense at the beginning of the polymerization process. For MWD, the model simulation showed that the existence of diffusion resistance led to have an increase in the molecular weight within a period of time similar to the one needed in the catalyst decay. Moreover, the validation of the model with experimental data given a good agreement results and show that the model is able to predict a correct monomer profile, polymerization rate, particle growth factor and MWD, an algorithm, which embeds physicochemical effects, has been developed to model the industrial reactors.     

Effects of fluorinated substituents on the refractive index and optical radiation resistance of methacrylates

Novel fluorinated methacrylate polymers were synthesized. The purpose was to produce polymers with low refractive indices and increased resistance to optical radiation damage. Six different fluorinated substituents were appended on the monomer before polymerization. Optical-quality samples were prepared, and their transmission spectra, through 0.8 cm thick samples, were obtained. Each sample was tested for refractive index and glass transition temperature. The samples absorbed 10 MRad gamma radiation from a ⁶⁰Co source in an air environment; their transmission spectra were recorded immediately after irradiation and again after seven days had elapsed. As expected, increasing the fluorine content in the side chains resulted in decreased refractive indices. Fluorine content also influenced optical radiation stability. One polymer, poly(1H,1H-heptafluorobutyl methacrylate) retained superior UV/visible transmission after irradiation. © 1993 John Wiley & Sons, Inc.     

How to speed up the UV curing of water-based acrylic coatings

Water-based polyurethane-acrylate (PUA) coatings have been cured, after drying, by a short exposure to UV radiation in the presence of a radical-type photoinitiator. The light induced polymerization has been followed quantitatively by means of real-time infrared spectroscopy, by monitoring continuously the disappearance of the acrylate double bonds. The UV curing of the dry film was markedly accelerated by adding to the PUA formulation a reactive plasticizer (diacrylate monomer), by operating in a humid atmosphere or by raising the temperature. The neutralizer of the carboxylic groups, needed to get a stable dispersion, plays a key role in both the polymerization kinetics and in the hydrophilic character of the UV-cured polymer, the best performance being achieved by using a volatile tertiary amine. Water-based UV-cured PUA coatings combine hardness and flexibility and are, therefore, quite resistant to abrasion and scratching. Presented at the Spring 2003 Meeting of the American Chemical Society, March 23–27, New Orleans LA.     

Evolution to similarity solutions for polymerization and depolymerization with microwave radiation

The kinetics of polymerization and depolymerization are critical in understanding the stability and characterization of polymers. The kinetics of simultaneous polymerization and degradation of poly(methyl methacrylate) have been investigated by varying the initiator concentration and monomer concentration under the influence of microwave energy. Microwave radiation initially polymerizes the monomer, then degrades the resulting polymer and the polymer attains an equilibrium molecular weight distribution with a polydispersity of two. To understand more fully the kinetics, the molecular weight distribution (MWD) is represented as a gamma distribution; the random degradation rate coefficient is assumed to vary linearly with molecular weight and the polymerization rate coefficient is assumed to be independent of molecular weight. The change of the MWD with time is studied by continuous distribution kinetics; the solutions obtained depict the change of the average molecular weight, polydispersity and the gamma distribution parameters with time. Experimental data indicate that reaction rates are enhanced by microwave radiation and the MWD approaches a similarity solution within 10 min for all the investigated cases. The model satisfactorily predicts the change of the MWD with time. © 2001 Society of Chemical Industry     

Poly(triallyl phosphate) and its copolymers with allyl diglycol carbonate as solid state nuclear track detectors.

This paper describes the design and development of new polymers for solid state nuclear track detection. A monomer triallyl phosphate (TAP) has been synthesized and cast homo/ copolymerized with allyl diglycol carbonate (ADC) to get transparent thin films of poly(triallyl phosphate) (PTAP) and poly(TAP-co-ADC) polymers respectively, which were successfully explored for the first time for detection of alpha particles and fission fragments. The polymerization kinetics studies were carried out to generate constant rate polymerization profile for TAP and TAP: ADC monomer mixture. Poly(TAP-co-ADC) copolymer in 3:7 wt./wt. ratio showed better radiation sensitivity as compared to indigenously prepared PADC and commercially available CR-39 detectors.     

多官能团单体对聚乙烯的增感辐致凝胶效应

研究了典型的多官能团单体三羟甲基丙烷三甲基丙烯酸酯（TMPTMA）对不同种类聚乙烯辐致凝胶效应的促进作用，实验表明：多官能团单体对聚乙烯早期的辐射交联有显著的促进作用，但随着剂量的增加，作用逐渐减弱直至消失，它对聚乙烯的极限凝胶分量几乎没有贡献，这种作用对聚乙烯的品种没有选择性，依据对实验事实的分析，多官能团单体对聚乙烯辐射交联的促进机理应是：辐射引发单体聚合，在聚合的同时向大分子链频繁发生链转移，从而形成大分五－单体聚合物之间的交联网络，由于更高的剂量率能够引发更多的聚合反应动力学链，所以有助于单体对交联促进作发挥。     

Graft polymerization of acrylamide onto UV-irradiated films

Graft polymerization of acrylamide was attempted onto the surface of films preirradiated with UV radiation. The films employed are nylon 6, polypropylene, and ethylene–vinyl acetate copolymers. Following UV irradiation in air on films without photosensitizer, they were placed in monomer solution, degassed, and then heated to 50°C to effect the graft polymerization. After rigorous removal of homopolymers, polyacrylamide chains were found to be grafted in the surface region of the films to amounts up to several hundred micrograms per square centimeter of films. An ESCA study revealed the UV-irradiated but not yet grafted surfaces to be oxidized, and formation of peroxides was strongly suggested by the reaction of irradiated films with 1,1-diphenyl-2-picrylhydrazyl. It is likely that the initiator responsible for the graft polymerization is peroxides generated at and near the film surfaces upon UV irradiation. The grafted films became very slippery when contacted with water, in contrast with the films UV-irradiated but not yet grafted.     

Investigation of the photoactivated frontal polymerization of oxetanes using optical pyrometry

An investigation of the photoactivated cationic ring-opening frontal polymerization of a series of 3,3-disubstituted oxetanes was carried out with the aid of a novel technique, optical pyrometry. Using this technique, the effects of various experimental parameters such as photoinitiator type and concentration, light intensity and sample configuration as well as the effects of monomer structure on the frontal behavior of these monomers were examined. Upon photoactivation with UV light, 3,3-disubstituted oxetanes display a long dormant period at room temperature as the result of the formation of metastable tertiary oxonium ions. Only small amount of thermal activation energy is required to induce the further reaction of these species with resulting exothermic autoaccelerated ring-opening polymerization. Frontal polymerization was observed for both mono- and difunctional oxetane monomers and the velocity of propagation of a given monomer was found to be related to its oxetane equivalent weight.     

Modification of adhesive properties of a polyethylene film by photografting

Graft polymerization of acrylic acid from monomer solutions in water or in bulk onto low‐density polyethylene film substrate was carried out by the method of continuous process under UV radiation. Effects of the nature of photoinitiator on acrylic acid grafting was first studied. One PI₂ and two PI₁ photoinitiators were used. Benzophenone was then retained for the following study. The influence of photoinitiator and monomer concentration was investigated by determining polymerization kinetics and grafted polymer amount. A study of surface wetting and morphological structure was then carried out on a bulk system and as a function of the photoinitiator concentration. Finally, such surface modification was studied with respect to its effect on the adhesion of an acrylic stick on its surface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2803–2811, 2004     

Chelating polymer granules prepared by radiation‐induced homopolymerization. I—Kinetic study of radiation polymerization process

Chelating polymer granules containing amidoxime chelating groups were synthesized by radiation‐induced homopolymerization of acrylonitrile monomer. The chemical reactive intermediate polyacrylonitrile was treated with hydroxylamine solution to convert the chemical active cyano groups into the amidoxime groups. Kinetic study of the effects of monomer concentration, radiation dose, dose rate, and temperature on the polymerization process was investigated. It was found that at low monomer concentration, the rate of polymerization is roughly independent on the initial monomer concentration, while at high monomer concentration, 35–65%, a marked acceleration on the rate was observed. The order of the dependence of the initial rate of polymerization on the dose rate is 0.77, which deviates from the classical square‐root law due to the precipitation of the formed polymer. The conversion percent and molecular weight of the produced polymer are inversely proportional to dose rate at constant radiation dose. The activation energy was found to be 2.7 kcal/mol, and the rate constant of initiation is independent of temperature. The effect of type of solvent on the polymerization was studied. DMF solvent of the closest solubility parameter to the solubility parameter of polyacrylonitrile is the best solvent for the polymerization process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1405–1412, 2000     

Transparent fluorocarbon-based semi-II IPN elastomers by high-energy radiation methods

Semi-II interpenetrating polymer network fluorocarbon elastomers were prepared by the addition of small amounts of a multifunctional monomer to the linear fluorocarbon polymer, followed by radiation polymerization in situ. The linear fluorocarbon is physically bound up with crosslinked network II, producing a semi-IPN of the second kind. Due to the high-energy radiation attack on the fluorocarbon backbone, a significant amount of graft copolymer forms which improves compatibility and yields clear, transparent elastomers. High-energy β and γ radiation produce very similar semi-IPN elastomers. Low-energy UV, which does not promote grafting, produces poorer quality elastomers which show significantly less optical clarity, much lower strength, and higher creep. High-energy radiation also appears to destroy possible incipient crystallinity thought to be present in the linear fluorocarbon material.     

Radiation grafting of methyl methacrylate monomer on natural rubber latex

A method of radiation grafting of methyl methacrylate (MMA) monomer on natural rubber (NR) latex has been studied. The irradiation dose in radiation emulsion polymerization of MMA monomer was lower compared to the irradiation dose for grafting of MMA monomer on NR latex, in order to obtain the same degree of conversion. This is due to the size of the rubber particles which are quite large and, hence, not sufficient to ensure an ideal emulsion polymerization. The irradiation dose for radiation grafting of MMA monomer on latex was around 300 krad to obtain a 75% degree of conversion. However, this irradiation dose was lower compared to the irradation dose for bulk polymerization of MMA monomer, in order to obtain the same degree of conversion. This is due to the gel effect in the viscous media. Radiation grafting of MMA monomer on NR latex does not influence the pH of the latex, but influences the viscosity significantly. The viscosity of the NR latex increased with an increase in irradiation dose, due to the increase of the total solid content in the latex. The MMA monomer converted to P-MMA in NR latex was largely grafted on the NR, or at least insoluble in a solvent for P-MMA, such as acetone or toluene. The hardness of the pure gum vulcanizate with an increase in the degree of grafting or P-MMA content, but the other physical properties, such as tensile strength, modulus, elongation at break, and thermal stability, were not greatly influenced by the degree of grafting.     

Surface graft polymerization of ionic monomers onto poly(ethylene terephthalate) by UV-irradiation without degassing

Graft polymerization of anionic and cationic monomers was performed onto the surface of poly(ethylene terephthalate) (PET) film with a simultaneous UV irradiation method, but using no photo-sensitizer. To effect graft polymerization, the PET film was immersed in an aqueous solution containing a monomer and periodate (NaIO₄) of appropriate concentrations, followed by UV irradiation without degassing. The monomers used were 2-acrylamide-2-methylpropane sulfonic acid and acrylic acid as anionic and N,N-dimethyl aminopropyl acrylamide and dimethyl aminoethyl methacrylate as cationic monomer. The role of NaIO₄ at the polymerization was to make the concentration of oxygen dissolved in solution zero by the photochemical reaction with the oxygen. The surface structure of grafted films was characterized by their contact angle, dyeing, X-ray photoelectron spectroscopy, and zeta potentials. Graft polymerization took place, not merely on the outermost surface, but also within the thin surface region of the PET film without any change in bulk properties. © 1993 John Wiley & Sons, Inc.     

Diffusion of Water through Poly(styrenesulfonate) membranes produced from the sulfonation of wasted PS plastic cups

Summary Two urethane carbazolyldiacetylenes, 6-(N-Carbazolyl)hexa-2,4-diyn-1-ol-1acetate buthyl urethane and 9-(N-carbazolyl)nona-5,7-diyn-1-ol-acetate buthyl urethane (hereafter named CHBU and CNBU, respectively), which present methylene spacers with different length between the urethane and diacetylene moieties, have been synthesized in order to obtain a conjugated polymer for non linear optics. The UV polymerization is studied by UV-Vis spectroscopy in polymeric films prepared by mechanical alignment of the monomer powder on hot substrates followed by UV polymerization. PolyCHBU films containing residual monomer exhibit thermochromic properties from blue to red form while no spectroscopic changes are observed for the polyCNBU films upon temperature. For polyCHBU, both blue and red films present also optical dichroism as observed by polarized UV-Vis spectroscopy, polarized microscopy and AFM.