Synthesis and characterization of three-component thermosetting acrylic polymer light conduits

In this study, new thermosetting acrylic polymer light conduits (PLCs) with the composition of A_xB_yC_z were prepared and characterized. The A and B components were methyl methacrylate and butyl acrylate, respectively. Tri-funcational acrylic monomers were used for the C component. The thermal properties and optical properties of the prepared PLCs are presented and compared with a commercially available PLC, S1. The prepared PLCs also have high numerical apertures and large diameters for illumination applications. The peak intensity and position can be tuned from their molecular structures. The peak position in the optical loss spectrum is in a satisfactory agreement with the theoretical calculation from the FTIR spectra, which results from the high harmonics of the C-H stretching vibration band. The peak intensity of the optical loss spectrum is proportional to the C-H bond density of the polymer core. The prepared PLCs have better thermal stability than S1.     

Graft copolymerization of n-vinyl-2-pyrrolidone on dimethyl sulfoxide pretreated poly(ethylene terephthalate) films using azobisisobutyronitrile initiator

Poly(ethylene terephthalate) (PET) films were grafted with n-vinyl-2-pyrrolidone (n-VP) using an azobisisobutyronitrile (AIBN) initiator. Films were pre-treated in dimethyl sulfoxide (DMSO) for 1 h at 140°C before the polymerization reaction was carried out. Variations of graft yield with time, temperature, initiator, and monomer concentrations were investigated. The optimum temperature and polymerization time was found to be 70°C and 4 h, respectively. Increasing monomer concentration from 0.28 to 1.22M and initiator concentration from 1.77 × 10⁻³ to 4.20 × 10⁻³M enhanced the percent grafting. The effects of monomer and initiator diffusion on PET films were also studied. The overall activation energy for grafting was calculated as 11.5 kcal/mol. Further changes in properties of PET films such as water-absorption capacity and intrinsic viscosity were determined. The grafted films were characterized with FTIR and scanning electron microscopy (SEM). © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1437–1444, 1997     

Ultrasonically initiated free radical‐catalyzed emulsion polymerization of methyl methacrylate (i)

The emulsion polymerization of methyl methacrylate initiated by ultrasound has been studied at ambient temperature using sodium lauryl sulfate as the surfactant. The investigation includes the: (1) nature and source of the free radical for the initiation process; (2) effects of different types of cavitation; and (3) dependence of the polymerization rate, polymer particle number generated, and the polymer molecular weight on acoustic intensity, argon gas flow rate, surfactant concentration, and initial monomer concentration. It was found that the polymerization could be initiated by ultrasound in the emulsion systems containing methyl methacrylate, water, and sodium lauryl sulfate at ambient temperature in the absence of a conventional initiator. The source of the free radical for the initiation process was found to come from the degradation of the sodium lauryl sulfate, presumably in the aqueous phase. The weight average molecular weight of the poly(methyl methacrylate) obtained varied from 2,500,000 to 3,500,000 g mol⁻¹, and the conversion for polymerization was up to 70%. Deviations from the Smith–Ewart kinetics were observed. The polymerization rate was found to be proportional to the acoustic intensity to the 0.98 power; to the argon gas flow rate to the 0.086 power; to the surfactant concentration to the 0.08 power, with the 0.035M–0.139M surfactant concentration range; and to the surfactant concentration to the 0.58 power, with the 0.139M–0.243M surfactant concentration range. The polymerization rate was found to increase with increasing initial monomer concentration up to a point where it became independent of initial monomer concentration. The polymer particle number generated per milliliter of water was found to be proportional to the acoustic intensity to the 1.23 power; to the argon gas flow rate to the 0.16 power; to the surfactant concentration to the 0.3 power, with the 0.035M–0.139M surfactant concentration range; and to the surfactant concentration to the 1.87 power, with the 0.139M–0.243M surfactant concentration range. The polymer weight average molecular weight was found to be proportional to the acoustic intensity to the 0.21 power, and to the argon gas flow rate to the 0.02 power. It was found to be inversely proportional to the surfactant concentration to the 0.12 and 0.34 power, with the 0.035M–0.139M and the 0.139M–0.243M surfactant concentration ranges, respectively. The polymer yield and polymerization rate were found to be much larger than those obtained from an ultrasonically initiated bulk polymerization method. The polymerization rates obtained at ambient temperature were found to be similar to or higher than those obtained from the conventional higher temperature thermal emulsion polymerization method. This investigation demonstrated the capability of ultrasound to both initiate and accelerate polymerization in the emulsion system, and to do this at a lower temperature that could offer substantial energy savings. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 797–825, 1999     

Synthesis and characterization of polymer light conduits

Summary Large diameter polymer light conduits are prepared for the first time by UV-curing. The polymer cores of the polymer light conduits are prepared from the copolymerization of various monomer mixtures in FEP tubes by UV curing, where FEP is used as the polymer cladding. The monomer mixtures consist of a multifunctional monomer for adjusting the heat resistance of the polymer cores and a monofunctional monomer for adjusting the flexibility. Experimental results indicate that the properties of the prepared polymer light conduits can be significantly modified by the formulations of the reactant mixtures. The onset thermal decomposition temperatures of the prepared polymer cores are 50°C to 79°C higher than that of the PMMA core. The glass transition temperatures and the refractive indices of the prepared polymer cores decrease from 78°C to -34°C and 1.490 to 1.474, respectively, when the contents of 2-ethyl-hexyl acrylate in the monomer mixtures increase from 0% to 70%. The prepared polymer light conduits conduits have large numerical apertures suitable for wide angle illumination applications.     

Experimental study of emulsion polymerization with crosslinking

Herein is reported the results of an extensive experimental investigation of the kinetics of emulsion polymerization as affected by crosslinking in the polymer particles. The model monomer system, methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA), was chosen for this study due to its earlier comprehensive investigation in bulk polymerization. Standard recipes with sodium dodecylsulfate (SDS) as anionic emulsifier and potassium persulfate (KPS) as initiator were used for the batch emulsion polymerizations. Results, which clearly show the effect of crosslinking on the kinetics, are discussed in detail. These include swellability of polymer particles by monomer; polymer particle nucleation rates, below and above the critical micelle concentration (CMC); average number of radicals per particle; and gel-sol levels. It was found advantageous to use electron spin resonance (ESR) to follow radical concentrations during crosslinking in polymer particles. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 935–957, 1997     

星形超支化聚酯改性丙烯酸酯树脂的制备及其水性涂料性能研究第一部分——星形超支化聚合物的合成及其影响因素

用树枝状超支化聚酯BoltornTM H20 (B-OH)与叔碳酸缩水甘油酯(E10P)进行阳离子开环接枝聚合,合成了星形超枝化聚合物B-PE 10P,研究了聚合反应条件对单体E10P转化率的影响,确定了较佳反应条件为∶n(E10P)∶n(—OH)=30,n [BF3O(C2H5)2]∶n(—OH)=1.0,以质量分数...     

Photo‐mediated metal free atom transfer radical polymerization of acrylamide in water

Photo‐mediated metal free atom transfer radical polymerization of acrylamide was conducted at 25 °C in water under visible light irradiation with water soluble 2‐hydroxy‐3‐(4‐benzoylphenoxy)‐N,N,N‐trimethyl‐1‐propaminium chloride (HBTPC) as photoredox catalyst and 2‐hydroxyethyl 2‐bromoisobutyrate as alkyl halide. The polymerization followed first‐order reaction kinetics. The living character of photo‐mediated atom transfer radical polymerization of acrylamide was verified by the linear development of the polymer number average molar mass (M_n,GPC) with monomer conversion and narrow molecular weight distributions (?). The effects of acrylamide concentration, light intensity, amount of HBTPC, and tris(2‐dimethylaminoethyl)amine on polymerization were investigated. Increasing monomer concentration led to a higher M_n,GPC values with narrow ?. The polymerization rate increased with increasing the amount of monomer, light intensity, HBTPC and tris(2‐dimethylaminoethyl)amine. The polymerization was monitored by the periodic light on/off. The structure of polyacrylamide was analyzed by proton nuclear magnetic resonance spectrometer and gel permeation chromatography. Successful chain extension experiments show the controlled nature of the polymerization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46567.     

Late Transition Metal Catalyst Based on Cobalt for Polymerization of Ethylene

The late transition metal catalyst of [2,6-diacethylpyridinebis(2,6-diisopropylphenylimine)]cobalt(II) dichloride was prepared under controlled conditions and used for polymerization of ethylene. Methylaluminoxane (MAO) and triisobuthylaluminum (TIBA) were used as a cocatalyst and a scavenger, respectively. The highest activity of the catalyst was obtained at about 30°C; the activity decreased with increasing temperature. At polymerization temperatures higher than 50°C not only was a sharp decrease in the activity observed but also low molecular weight polyethylene product that was oily in appearance was obtained. The polymerization activity increased with increasing both of the monomer pressure and [MAO]:[Co] ratio. However, fouling of the reactor was strongly increased with increasing both of the monomer pressure and the amount of MAO used for the homogeneous polymerization. Hydrogen was used as the chain transfer. The activity of the catalyst and the viscosity average molecular weight (M_v) of the polymer obtained were not sensitive to hydrogen concentration. However, the viscosity average molecular weight of the polymer decreased with the monomer pressure. The (M_v), the melting point, and the crystallinity of the resulting polymer at the monomer pressure of 1 bar and polymerization temperature of 20°C were 1.2 × 10⁵, 133°C, and 67%, respectively. Heterogeneous polymerization of ethylene using the catalyst and the MAO/SiO₂ improved morphology of the resulting polymer; however, the activity of the catalyst was also decreased. Fouling of the reactor was eliminated using the supported catalyst system.     

Analysis of thermosetting acrylic polymer light conduits

In this study a series of thermosetting acrylic polymer light conduits (PLCs) with the composition of A_xB_yC_z were synthesized to investigate the structure–property relationships. The A and B components were selected from methyl methacrylate (MMA), butyl acrylate (BA), or 2,2,3,3‐tetrafluoropropyl methacrylate (TFPMA). Various bifunctional acrylics were used for the C component. High numerical aperture values were found in the prepared large‐diameter PLCs. The peak maxima of the optical loss spectra vary from 735 nm to 745 nm, which satisfactorily agree with the theoretical calculation from the FTIR spectra. They are due to the fifth harmonic of the C—H stretching vibration band. The peak maximum and intensity can be adjusted by varying molecular composition. The peak intensity of the optical loss spectrum is proportional to the C—H bond density of the polymer core. The replacement of the MMA moiety by the TFPMA moiety in the three‐component thermosetting PLCs reduces the peak intensity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 2098–2104, 2000     

Synthesis and hydrolysis study of polyacrylates containing 2′,5-dichloro-4′-nitrosalicylanilide

Monomers (meth)acryloyloxy-2′,5-dichloro-4′-nitrosalicylanilide have been synthesized by treating 2′,5-dichloro-4′-nitrosalicylanilide (niclosamide) with acryloyl or methacryloyl chloride, and polymerized by free radical polymerization to give a polymer containing chemically bonded niclosamide. The structure of monomer and polymer were confirmed by IR, UV, and elemental analysis. Hydrolysis data of polymer in different media indicated that the hydrolysis rates of polymer were strongly dependent on the nature of the polymer structure and the hydrolyzing medium. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 29–33, 1997     

Investigation of kinetics of 4‐methylpentene‐1 polymerization using Ziegler–Natta‐type catalysts

The kinetics of 4‐methylpentene‐1 (4MP1) polymerization by use of Ziegler–Natta‐type catalyst systems, M(acac)₃‐AlEt₃ (M = Cr, Mn, Fe, and Co), are investigated in benzene medium at 40°C. The effect of various parameters such as Al/M ratio, reaction time, aging time, temperature, catalyst, and monomer concentrations on the rate of polymerization and yield are examined. The rate of polymerization increased linearly with increasing monomer concentration with first‐order dependence, whereas the rate of polymerization with respect to catalyst concentration is found to be 0.5. For all cases, the polymer yield is maximum at an Al/M ratio of 2. The activation energies obtained from linear Arrhenius plots are in the range of 25.27–33.51 kJ mol^?1. It is found that the aging time to give maximum percentage yield of the polymer varies with the catalyst systems. Based on the experimental results, a plausible mechanism is proposed that envisages a free‐radical mechanism. Characterization of the resulting polymer product, for all the cases, through FTIR, ¹H‐NMR, and ¹³C‐NMR studies, showed isomerized polymeric structures with 1,4‐structure as dominant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2468–2477, 2003     

New polymerization of dienes and related monomers catalyzed by late transition metal complexes

This article reviews recent studies on the polymerization of 1,6-heptadienes and 2-aryl- and 2-alkoxy-1-methylenecyclopropanes catalyzed by Co, Fe, and Pd complexes. Co and Fe complexes with bis(imino)pyridine ligands catalyze the cyclopolymerization of 1,6-heptadiene in the presence of MMAO to produce the polymer, which contains five-membered rings in the monomer units. The polymers with cis- or trans-five-membered rings are obtained selectively, depending on the complex used in the polymerization. The catalyst, prepared from the Co complex having a bis(imino)pyridine ligand and MMAO, promotes the polymerization of 2-aryl-1-methylenecyclopropanes without ring-opening. The reaction under ethylene atmosphere produces alternating copolymer of the two monomers to yield the polymers composed of the C4 repeating unit with a 1,1-cyclopropanediyl group. The alternating copolymer of ethylene and 7-methylenebicyclo[4.1.0]heptane undergoes thermal rearrangement to afford the polymer with CC double bond in main chain. A radical pathway is proposed. Dinuclear π-allylpalladium complexes with bridging Cl ligands initiate living polymerization of 2-alkoxy-1-methylenecyclopropanes, which accompanies ring-opening of the monomer, to afford the polymers composed of the C₃ repeating units having alkoxy and vinylidene groups. A cyclic dinuclear π-allylpalladium complex reacts with 2-alkoxy-1-methylenecyclopropane in the presence of pyridine to produce the living polymer with macrocyclic structures. Block copolymerization of the two monomers that contain OR or O(CH₂CH₂O)R as the substituents on the three-membered ring, results in the polymers with hydrophobic and hydrophilic segments.     

A comparative study on effects of two kinds of polymerization methods on grafting of polymer onto silica surface

In this article we present the result of a comparative study of two kinds of polymerization methods—solution polymerization (sol. poly.) and dispersion polymerization (dis. poly.) for grafting polymer onto silica. As a model for the grafting polymerization reaction, styrene was chosen as the monomer and azo diisobutyronitrile (AIBN) as the initiator. The study aims at supplying theoretical reference for better selecting polymerization method to graft polymer on the silica particle surface. First, monolayers of 3‐methacryloylpropyl trimethoxysilane were chemically bonded onto the surfaces of micrometer‐sized silica gel particles, and so double bonds were immobilized onto the silica surface. Second, the copolymerizations between the immobilized double bonds and the monomer styrene were carried out, homopolymerizations of styrene followed, and finally polystyrene was grafted to the silica surfaces. Two kinds of polymerization methods, sol. poly. and dis. poly., were adopted respectively, and the effects of polymerization methods on grafting process were examined mainly. At the same time, the effects of different polymerization conditions on the grafting degree were researched. It was found that in the dis. poly. system the grafting degree is obviously higher than that in the sol. poly. system under the same polymerization conditions, and the grafting degree can go up to 47%, i.e. 47g/100g. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5808–5817, 2006     

Resistivity of conductive polymer–coated fabric

Preparation of conductive polymer–coated fabrics was carried out by admicellar polymerization. By this method, a thin layer of conductive polymers (polypyrrole, polyaniline, and polythiophene) was formed on cotton and polyester fabrics by a surfactant template. The effects of monomer concentration, oxidant to monomer ratio, and addition of salt on the resistivity of the resulting fabrics were studied. The results showed that the apparent surface and volume resistivity decreased with an increase in monomer concentration in the range 5–15 mM, but was not strongly dependent on the oxidant to monomer ratio over the range of 1 : 1 to 2 : 1. Addition of 0.5M salt was found to reduce the resistivity significantly. The lowest resistivity obtained was with polypyrrole‐coated fabric, with resistivity around 10⁶ ohm. SEM micrographs of the treated fabric surface showed a filmlike polymer coating, confirming that the fabrics were successfully coated by admicellar polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2629–2636, 2004     

Modelling of polymerization kinetics and molar mass development in the nitroxide-mediated polymerization (NMP) of styrene in supercritical carbon dioxide using the PC-SAFT equation of state

A mathematical model for polymerization kinetics and molar mass development in the nitroxide-mediated polymerization (NMP) of vinyl monomers in supercritical carbon dioxide (scCO₂) has been developed. The method of moments is used for molar mass development. The perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state is used to estimate the number of stable phases present at equilibrium in the reaction mixture, critical number average chain length at which polymer particles are formed, and monomer concentration in each phase. Pure and binary PC-SAFT interaction parameters are estimated from liquid–liquid equilibrium (LLE) and liquid–vapour equilibrium (LVE) experimental data at 60 to 129°C. The effect of pressure on monomer conversion and molar mass development in the polymerization of styrene (Sty) using benzoyl peroxide (BPO) and 2,2,6,6-Tetramethylpiperidinyl-1-oxyl (TEMPO) at 120°C and 300–500 bar is studied. It was observed that increasing pressure increases polymerization rate without significantly affecting molar mass development.     

Amphoteric hydrogels for immobilization of enzymes using template polymerization technique

Novel ionizable amphoteric hydrogels were prepared from poly(acrylic acid) and dimethylaminoethyl methacrylate monomer, employing template polymerization technique. The mode of interaction, as proved by FTIR, was multiple H‐bonding between the tertiary amino group of the monomer and the carboxylic groups of the polymer. The impact of varying equal polymer–monomer feed ratios from 0.1 to 1.1 on the swelling dynamics was examined. Penetrant sorption experiments demonstrated that the swelling behavior depends strongly on the polymer complex composition. The polymer complex of feed ratio 0.5 : 0.5 (polymer : monomer) showed maximum swelling percentage. The mechanism of the polymer complexes swelling was probably a non‐Fickian with n values approaching Fickian behavior. The hydrogels showed maximum swelling efficiencies of 27 folds and 13.5 folds in drastic acidic and basic medium, respectively, using polymer complex of 0.5 : 0.5 feed ratio. Because of reversibility and rapidity of swelling, the gel could be considered as a mechanochemical system. The prepared hydrogel successfully immobilized the industrially used β‐galactosidase as an acidic model enzyme. The novel immobilized enzyme showed a remarkable improvement in its activity (13.8 μmol min^?1 mg^?1) compared to the free enzyme (3.2 μmol min^?1 mg^?1). The optimum pH values for free and immobilized enzyme were 4.5–5 and 4, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Ultrasonically initiated emulsion polymerization of n‐butyl acrylate

Ultrasonically initiated emulsion polymerization of n‐butyl acrylate (BA) without added initiator has been studied. The experimental results show that high conversion of BA can be reached in a short time by employing an ultrasonic irradiation technique with a high purge rate of N₂. The viscosity average molecular weight of poly(n‐butyl acrylate) (PBA) obtained reaches 5.24 × 10⁶ g mol^?1. The ultrasonically initiated emulsion polymerization is dynamic and complicated, with polymerization of monomer and degradation of polymer occurring simultaneously. An increase in ultrasound intensity leads to an increase in polymerization rate in the range of cavitation threshold and cavitation peak values. Lower monomer concentration favours enhancement of the polymerization rate. ¹H NMR, ¹³C NMR and FTIR spectroscopies reveal that there are some branches and slight crosslinking, and also carboxyl groups in PBA. Ultrasonically initiated emulsion polymerization offers a new route for the preparation of nanosized latex particles; the particle size of PBA prepared is around 50–200 nm as measured by transmission electron microscopy. © 2001 Society of Chemical Industry     

Preparation of SBS/poly(styrene–methyl methacrylate) thermoplastic interpenetrating polymer network

SBS as polymer I, poly(styrene–methyl methacrylate) polymerized by atom transfer radical polymerization as polymer II, and a thermoplastic interpenetrating polymer network of SBS/poly(styrene–methyl methacrylate) were prepared by the sequential method. The effects of the polymerization temperature, the composition of the catalyst, the ratio of the monomers studied, and the kinetics at 90°C were also investigated. It was shown that when polymerization was initiated by a BPO/CuCl/bpy (BPO:CuCl:bpy = 1:1:3) system at 90°C, the mass averaged molecular weight of the poly(styrene–methyl methacrylate) increased with monomer conversion, and the polydispersities were kept very low. Fourier transform infrared spectroscopy and gel permeation chromatogram showed that poly(styrene–methyl methacrylate) with low polydispersities had been synthesized. Thus, a thermoplastic interpenetrating polymer network comprised of both narrow molecular‐weight‐distribution components was successfully prepared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2007–2011, 2003     

PAN/氧化石墨烯纳米复合材料的热性能研究

采用原位聚合的方法制备了聚丙烯腈(PAN)/氧化石墨烯(GO)纳米复合材料;利用红外光谱和紫外光谱表征了试样的组成及组分间的相互作用;使用扫描电镜和透射电镜对试样的微观形貌进行观察;从单体转化率和聚合液的黏度变化研究了GO对丙烯腈自由基聚合的影响;用热分析仪分析了GO对PAN热稳定化过程的影响。结果表明:复合体系聚合至13 h时,与空白试样(PAN)相比,聚合液的黏度和单体转化率分别降低了1.3%和2.9%,说明在聚合前期GO对自由基聚合起到一定的阻聚作用;GO的厚度由聚合前的3～4 nm剥离到聚合后的1 nm,表明GO在原位聚合过程中以单层形式分散在PAN基体中;PAN与GO之间存在较强的π-π相互作用,这种相互作用抑制了PAN在热稳定化过程中的环化反应。     

Solid‐supported synthesis of hyperbranched polymer with β,β‐diethynylstyryl units

Two novel aromatic polyamide supports bearing aromatic bromine and iodine functionality have been synthesised and tested for the solid‐supported polymerization of AB₂ type monomer 4‐(5‐hexynyloxy)‐β,β‐dibromostyrene via Pd‐catalysed cross‐coupling of vinyl halides and terminal acetylenes. It was found that the solid‐supported polymerization leads to a decrease in molecular weight and increase in the degree of branching from 17 000–18 000 g mol⁻¹ to 8000–4000 g mol⁻¹ and from 30–35 % to 50–65 %, respectively, compared to solution polymerization. All other things being equal, the decrease in molecular weight of hyperbranched polymer on solid‐supported polymerization is a function of the distance between adjacent active sites of the polymer support. © 2001 Society of Chemical Industry