Effect of molecular weight on the surface morphology of crosslinked polymer particles in the RITP-dispersion polymerization

The RITP (reverse iodine transfer polymerization)-dispersion polymerization of methyl methacrylate (MMA) was conducted and the molecular weight and SEM images of them were investigated to propose the mechanism of the formation of surface morphology in crosslinked polymers. The morphology of the crosslinked particles varied depending on the sorts and contents of the crosslinking agents and iodine. As the iodine content increased under the same content of the crosslinking agent, the average molecular weight of the polymers [uncrosslinked portion of the polymers] decreased and the surface roughness simultaneously reduced. On the other hand, as the contents of the crosslinking agent increased, the molecular weight of polymers reduced and the surface morphology changed from smooth to rough in the absence of iodine. On the other hand, was the molecular weight was barely changed and the solubility increased upon iodine. Thus the mechanism of the formation of crosslinked polymers in the RITP-dispersion polymerization was proposed as the following; when crosslinking agent and iodine were simultaneously involved, the low molecular weight of polymers were first formed due to the effect of iodine and then the crosslinking was taking place, resulting in that iodine was a critical factor in controlling the molecular weight, particle size, solubility and the surface morphology in the crosslinked polymer particles.     

中空聚合物乳胶粒子的制备

研究了在制备中空乳胶粒子的过程中,复合乳液（苯乙烯（Ｓｔ）－丙烯酸丁酯（ＢＡ）－甲基丙烯醛（ＭＡ））进行种子聚合时,Ｓｔ／ＢＡ的质量比和ＭＡ的用量对胶乳粒子的空径、粒径和表面羧基质量摩尔浓度的影响。实验结果表明,当Ｓｔ／ＢＡ的质量比为１９,ＭＡ质量分数为单体的５．６％时,形成的乳胶粒子的空径最大。     

交联聚合物颗粒深部调驱技术的应用

为提高交联聚合物颗粒在高含水、非均质性严重的油藏中深部调驱的应用效果,通过粒径分析、岩心驱替等实验对交联聚合物颗粒分散体系的调驱适应性进行了研究,得到了孤岛污水配制的交联聚合物分散体系在60℃条件下溶涨10 d后粒径中值增大了34倍;其单管岩心封堵率大于92%,双管岩心驱油实验提高采收率大于11%,在由6 口水井和17口油井组成的现场试验中平均注入油压上升了1.2 MPa,对应中心油井见效高峰期含水率下降了5.6%,平均增产原油5 t/d.表明了交联聚合物颗粒分散体系完全能够满足孤岛高渗透油藏深部调驱的要求,交联聚合物颗粒深部调驱技术是改善注水剖面和降低油井含水率的有效方式.     

Synthesis of poly(tetrafluoroethylene)/poly(butadiene) core-shell particles and their graft copolymerization

This article describes how to convert the unreactive surface of poly(tetrafluoroethylene) (PTFE) into poly(styrene-co-acrylonitrile) (SAN). Composite particles with a crosslinked poly(butadiene) (PB) shell covered over a PTFE core were prepared by an emulsifier-free seeded emulsion polymerization of butadiene in the presence of PTFE latex. It was found that the increase in the PB crosslink density resulted in depressing the formation of PB secondary particles. Then, styrene and acrylonitrile were able to graft onto PB shell in high efficiency of 70%. SAN-modified PTFE/PB core-shell particles could eventually be dispersed homogeneously in a SAN matrix. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:185–190, 1998     

Characterization of sulfonated poly(styrene–divinylbenzene) and poly(divinylbenzene) and its application as catalysts in esterification reaction

Polymeric supports based on divinylbenzene (DVB) were prepared by aqueous suspension polymerization in presence or absence of styrene (S), using toluene and n‐heptane as diluents of the monomers. Poly(S–DVB) and poly(DVB) were sulfonated with sulfuric acid in presence of 1,2‐dichloroethane. The influence of the morphological structure of the supports and as a consequence of the catalyst on the esterification reaction of acetic acid with n‐butanol was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3616–3627, 2006     

Chromatographic performance of monodisperse–macroporous particles produced by “modified seeded polymerization.” I: Effect of monomer/seed latex ratio

In this study, the monodisperse–macroporous particles produced by a relatively new polymerization protocol, the so‐called, “modified seeded polymerization,” were used as column‐packing material in the reversed phase chromatography (RPC) of proteins. The particles were synthesized in the form of styrene‐divinylbenzene copolymer approximately 7.5 μm in size. In the first stage of the synthesis, the monodisperse polystyrene particles 4.4 μm in size were obtained by dispersion polymerization and used as the “seed latex.” The seed particles were swollen by a low‐molecular‐weight organic agent and then by a monomer mixture. The monodisperse–macroporous particles were obtained by the polymerization of monomer mixture in the seed particles. In the proposed polymerization protocol, the number of successive swelling stages was reduced with respect to the present techniques by the use of sufficiently large particles with an appropriate average molecular weight as the seed latex. A series of particles with different porosity properties was obtained by varying the monomer/seed latex ratio. The separation behavior of HPLC columns including the produced particles as packing material was investigated in the RPC mode using a protein mixture including albumin, lysozyme, cytochrome c, and ribonuclease A. The chromatograms were obtained with different flow rates under an acetonitrile–water gradient. The theoretical plate number increased and chromatograms with higher resolutions were obtained with the particles produced by using a lower monomer/seed latex ratio. The separation ability of the column could be protected over a wide range of flow rates (i.e., 0.5–3 mL/min) with most of the materials tested. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 607–618, 2004     

Synthesis of well‐defined poly(vinyl ether)‐based macromonomers having pendant glycerols via living cationic polymerization and their application to the preparation of core−shell polymer particles

A new vinyl ether monomer bearing a glycerol pendant moiety protected with an isopropylidene group (2‐(2,2‐dimethyl‐[1,3]dioxolan‐4‐ylmethoxy)‐ethyl vinyl ether, IpGEVE) was designed as the precursor of a novel type of hydrophilic poly(vinyl ether) containing glycerol pendants. It was found that the polymerization of IpGEVE proceeded in a controlled manner, and the protecting groups of isopropylidene moieties could be cleaved with trifluoroacetic acid. Living cationic polymerization of IpGEVE with an initiator bearing a methacryloyl group (VEM‐HCl) and subsequent deprotection of the pendant isopropylidene groups of the resultant precursor afforded a glycerol‐substituted hydrophilic macromonomer MA‐PGEVE. Nearly monodispersed polymer particles in the submicron size range were successfully obtained via dispersion copolymerization of MA‐PGEVE with styrene.© 2013 Society of Chemical Industry     

Surface morphology evaluation of polymer beads based on divinylbenzene by atomic force microscopy

Macroporous poly(styrene‐co‐divinylbenzene) and poly(divinylbenzene) beads were synthesized by modified suspension polymerization in the presence of different mixtures of toluene and heptane as porogen agent. Through atomic force microscopy, it was possible to identify the microspheres and the channels between them that constitute the bead pores. It was also possible to make a comparison with the results obtained by nitrogen desorption, a traditional technique used to determine the porosity of macroporous copolymers in the dry state. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 541–551, 2002; DOI 10.1002/app.10290     

Simultaneous novel synthesis of conducting,nonconducting, and crosslinked polymers by microwave initiation

A novel synthesis of poly(dibromophenylene oxide) (P), conducting polymer (CP), and/or crosslinked polymer (CLP), and/or radical ion polymers (RIP) was achieved simultaneously from sodium 2,4,6‐tribromophenolate by microwave energy in a very short‐time interval. The synthesized polymers were characterized via elemental analysis, FTIR, ¹H NMR and ¹³C NMR, X‐ray diffraction spectroscopy, SEM, DSC, TGA, ESR, GPC, conductivity measurement, and light scattering. It was found that polymerization proceeds through both 1,2‐ and 1,4‐addition at equal rates. The effects of the energy and time on the % conversion and the polymer synthesis were investigated. The optimum condition for synthesis of P (the highest M_w, 2.97 × 10⁵ g/mol) and CP was 70 W for 5 min in 5 mL water and 100 W for 1 min in 0.5 mL water, having maximum values 23.6% and 27.2%, respectively. In addition, synthesis of CLP and RIP were achieved in 5 mL water at 350 W and 700 W at the end of 1 min, respectively. The direct synthesis of highly conducting polymer, with the conductivity of 1 S cm^?2 was achieved in the absence of applied doping process in a very short time sequence. P, CP, CLP, and RIP had fine granular, sponge‐like, dendrite, and coarse surface structures, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5427–5435, 2006     

Morphology and thermal properties of two polymethacrylates modified by a polymer liquid crystal

We have studied blends of a polymer liquid crystal (PLC) with poly(cyclohexylethyl methacrylate) (PCHEMA) or poly(cyclohexylpropyl methacrylate) (PCHPMA). The PLC is PET/0.6PHB where PET = poly(ethylene terephthalate), PHB = p-hydroxybenzoic acid and 0.6 is the mole fraction of the latter in the copolymer. The microstructure was studied by scanning electron microscopy (SEM). PCHEMA + PLC (20 wt% of the latter, blend E) has a fine texture with LC islands evenly distributed in the matrix and good adhesion between the phases resulting from their partial miscibility. The PCHPMA + PLC (20 wt% of the latter, blend P) shows only limited compatibility. The SEM results are confirmed by values of the glass transition temperatures T_g determined via thermal mechanical analysis. The T_g value of the blend E is shifted towards the T_g of PLC; T_g of blend P is practically equal to that of PCHPMA. The linear isobaric expansivity α_L values for both blends are lower than the respective values for pure PCHPMA and PCHEMA. Thermal stabilities of the blends determined by thermogravimetry are also better than those of pure polymethacrylates. The temperature of 50% weight degradation for blend E is higher than that for pure PCHEMA by more than 60 K Copyright © 2004 Society of Chemical Industry     

Efficient adsorption of oil by hydrophobic macroporous polymer synthesized with the emulsion template and magnetic particles on the surface

Fast development of oil industry and cargo distribution make accidental oil spills more possible in the course of transportation. Here we fabricated a hydrophobic macroporous phenol resin poly high internal phase emulsions (poly‐HIPEs) to adsorb oil pollution. To improve hydrophobic property and adsorption ability of the poly‐HIPEs, we adopted a facile way to modify the poly‐HIPEs that Fe₃O₄ nanoparticles act as magnetic particles to make the poly‐HIPEs magnetic and 1‐dodecanethiol as hydrophobic monomer grafted to the surface to strengthen the hydrophobicity with dopamine as the adhesive. As a result, we succeed in making the poly‐HIPEs superhydrophobic and their contact angle transforms from 107° to 150°. After the oil adsorption experiment, the adsorption capacity of the modified poly‐HIPEs is obviously better than the original poly‐HIPEs which is about ten times than original weight of material, what's more, the final products also have good recycle ability after ten times' employing, which makes it a promising candidate material for use in oil‐spill cleanups. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44731.     

Preparation of hydrophobic polymer particles by radical polymerization and subsequent modification into magnetically doped particles

The application potential of hydrophobic polymer is numerous. Lauryl methacrylate (LMA) having long alkyl chain is a commercially available hydrophobic monomer. In this investigation, poly‐LMA (PLMA) latex particles were prepared by suspension polymerization in aqueous media using 2,2′‐azobis(isobutyronitrile) (AIBN) in presence of poly(vinyl alcohol) (PVA) as steric stabilizer. The preparation kinetics was studied in detail in terms of percentage yield and particle size variation. Low glass transition temperature (～ ?65°C) associated with high flexibility did not allow electron micrographic observation though ¹H‐NMR and particle size measurement confirmed the formation of PLMA latex. To improve the glass transition temperature, aqueous emulsion copolymerization of LMA with methyl methacrylate (MMA) was carried out. The solubility of LMA was improved by adding ethanol to the aqueous phase. Two types of polymeric stabilizers, PVA and poly(vinyl pyrrolidone) (PVP) were used to stabilize the colloidal particles. The nature of the stabilizer affected both morphology and final rate of polymerization. The hydrophobic P(LMA‐MMA) copolymer particles were subsequently modified by nanosized magnetic (Fe₃O₄) particles by two different methods. The in situ formation of Fe₃O₄ particles in presence of P(LMA‐MMA) was found to be suitable for the preparation of magnetic latex particles. Scanning electron microscope (SEM), FTIR, transmission electron microscope (TEM), X‐ray diffraction (XRD) and energy‐dispersive X‐ray spectroscopy (EDX) were used for the characterization of magnetically doped particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Sonochemical synthesis of monosized spherical BaTiO3 particles

Monosized spherical particles of BaTiO₃ have been successfully synthesized by a sonochemical method in a strong alkaline environment using BaCl₂·2H₂O as the barium source and TiCl₄ as the titanium source. The as-prepared BaTiO₃ powders were characterized by employing techniques including X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive analysis of X-rays (EDAX) and laser particle size analyzer. The effects of reactant concentrations and Ba/Ti molar ratio on the precipitation of BaTiO₃ particles were briefly investigated. The particles have a monosized spherical morphology and the particle size ranges from submicron (600-800 nm) to nanometer (60-70 nm) by increasing the reactant concentration (from 0.072 mol/L to 0.72 mol/L). The studies indicated that increasing the Ba/Ti ratio can promote synthesis of BaTiO₃.     

Chlorinated crosslinked adsorbents

High crosslinked copolymers based on poly(ethylstyrene-co-divinylbenzene), bead shaped, have chlorinated, resulting in adsorbents with a high content of chlorine (45.0% Cl). The chlorination process of the copolymer beads (0.40–0.80 mm in diameter) was carried out in 1,2-dichloroethane in the presence of a Friedel–Crafts catalyst (AlCl₃, FeCl₃), at 5–40°C, yielding yellow beads without any cracks and good mechanical strength. The chlorination degree of the samples is high because each vinyl aromatic unit contains 1.8–2.2 chlorine atoms. The chlorinated copolymer samples were used to retain Cephalosporine C from standard solutions comparatively with commercial adsorbents (Amberlite XAD-4 Rohm, Haas Co.; SP-206/7, Mitsubishi Kasai Corp., Japan). © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1579–1587, 1998     

Synthesis of monodisperse nonporous crosslinked poly(glycidyl methacrylate) particles with metal affinity ligands for protein adsorption

Monodisperse nonporous crosslinked poly(glycidyl methacrylate) (PGMA) particles with immobilized metal affinity ligands were prepared for selective recovery of proteins. The PGMA particles, with an average size of 2.2 µm, were prepared by a simple dispersion polymerization of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA). The particles were characterized by scanning electron microscopy (SEM) and Fourier‐transform infrared spectroscopy (FTIR). The epoxy groups of the particles were modified with the metal chelating agent iminodiacetic acid (IDA), which forms metal–IDA chelates at the active sites. After charging with copper ions, the particles were used to recover a model protein, bovine hemoglobin (BHb), in a batchwise manner. The particles had the adsorption capacity of 218.7 mg g⁻¹ with little nonspecific adsorption. The adsorption behavior could be described with the Langmuir equation. The effect of pH on the adsorption was also studied. Regeneration of the metal‐chelated particles was easily performed with 50 mmol L⁻¹ ethylenediaminetetraacetic acid (EDTA), followed by washing with water and reloading with Cu²⁺. The particles could be very useful as an affinity separation adsorbent. Copyright © 2005 Society of Chemical Industry     

Highly crosslinked micron‐sized,monodispersed polystyrene particles by batch dispersion polymerization,Part 1: Batch,delayed addition,and seeded batch processes

The seeded batch dispersion polymerization with or without monomer absorption was compared with the batch polymerization and delayed addition by batch polymerization, to prepare the highly crosslinked, monodispersed polystyrene (PS) particles. The seeded batch polymerization was carried out under the variation of styrene (in second stage)/styrene (in PS seed) (St/St) ratio, divinylbenzene (DVB) concentration, and polymerization temperature using 1.9‐μm monodispersed PS seed particles. The experimental results imply that the seeded batch process is more efficient method that could avoid the sensitive particle nucleation step in the presence of the crosslinker than the batch and delayed addition processes. Without monomer absorption, 2.3‐μm uniform crosslinked PS particles with 7 wt % of the DVB were prepared in 1/1 (St/St) ratio. In comparison, with the monomer absorption, monodispersed and smooth‐surfaced PS particles containing 20 wt % of the DVB were formed. A total of 5% weight loss of the crosslinked PS particles determined by TGA occurred from 353.8 to 374.8°C, and the degree of swellability in toluene decreased from 150 to 104.5% with increasing the DVB concentration from 5 to 20 wt % because of the increase of the crosslink density of the particles. The seeded polymerization, especially through monomer absorption procedure, is a novel way to obtain highly crosslinked, monodispersed PS particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Highly crosslinked micron‐sized,monodispersed polystyrene particles by semicontinuous dispersion polymerization. II. Semicontinuous,delayed addition and seeded semicontinuous processes

A highly crosslinked, monodispersed polystyrene (PS) particle was prepared by the seeded semicontinuous dispersion polymerization using ready‐made monodispersed PS seed particles. The effects of Styrene (in 2nd stage)/Styrene (in PS seed) ratio, addition point and feeding time of divinylbenzene (DVB), concentration of DVB and polymerization temperature on the particle size, size distribution and morphology of the resulting particles were investigated. Monodispersed PS particles with 15 wt % of the DVB were prepared at 1/1 in St/St ratio, In comparison, highly crosslinked monodispersed and smooth‐surfaced PS particles containing up to 70 wt % of the DVB were effectively prepared at 0/1. 5% weight loss of the PS particles determined by TGA occurred from 353.3 to 389.6°C and the degree of swellability in toluene decreased from 113 to 101% as the DVB concentration increased from 10 to 70 wt %, implying increased thermal stability and solvent resistance due to the increase of the crosslink density. This study demonstrates that the seeded semicontinuous process, primarily with the starved condition at the second stage, is an efficient way to obtain highly crosslinked, monodispersed PS particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical and dielectric breakdown properties of PBT/TPE,PBT/PBT/PET,and PBT/antioxidant blends

To improve the thermal aging flexibility of poly(butylene terephthalate) (PBT), PBT was melt‐blended with three type thermoplastic elastomer [poly ether‐ester type (TPE1), polyester‐ester type (TPE2), and poly(buthylene 2,6‐naphthalate)/poly(tetramethylene glycol) block copolymer type (TPE3)], PBT/poly(ethylene terephthalate), (PET) alloy (Alloy), and phosphate type antioxidant (T1). The content of the three type TPEs and Alloy was fixed at 20 parts per 100 g of PBT. The morphology and thermal behavior of these blends have been investigated with scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetry (TG). In the case of PBT/Alloy‐20 and PBT/TPE3–20 blends show clean fractured surface, whereas for PBT/TPE1–20 and PBT/TPE2–20 blends, the elongated pieces or fiber can be seen abundantly which indicates a good compatibility. TG traces show a significant shift of the weight loss toward higher temperature for PBT/Alloy‐20, whereas PBT/TPE1–20, PBT/TPE2–20 and PBT/TPE3–20 blend decrease in thermal stability than PBT. To investigate the applicability for insulation material, the prepared blend samples were extruded an electric wire and flexibility and electric breakdown voltage (BDV) of wire after thermal aging were studied. For PBT/TPE1–20 and PBT/TPE2–20 blends did not show any cracks after flexibility test at 130°C for 6 h and 225°C for 30 min. In contrast PBT, PBT/Alloy‐20, PBT/TPE3–20, and PBT/T1–1 showed a partial crack in the insulation after flexibility test at 130°C for 6 h although its good flexibility at 225°C for 30 min. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization and preparation of new multiwall carbon nanotube/conducting polymer composites by in situ polymerization

Composites based on poly(diphenyl amine) (PDPA) and multiwall carbon nanotubes (MWNTs) were prepared by chemical oxidative polymerization through two different approaches: in situ polymerization and intimate mixing. In in situ polymerization, DPA was polymerized in the presence of dispersed MWNTs in sulfuric acid medium for different molar composition ratios of MWNT and DPA. Intimate mixing of synthesized PDPA with MWNT was also used for the preparation of PDPA/MWNT composites. Transmission electron microscopy revealed that the diameter of the tubular structure for the composite was 10–20 nm higher than the diameter of pure MWNT. Scanning electron microscopy provided evidence for the differences in the morphology between the MWNTs and the composites. Raman and Fourier transform IR (FTIR) spectroscopy, thermogravimetric analysis, X‐ray diffraction, and UV–visible spectroscopy were used to characterize the composites and reveal the differences in the molecular level interactions between the components in the composites. The Raman and FTIR spectral results revealed doping‐type molecular interactions and coordinate covalent‐type interactions between MWNT and PDPA in the composite prepared by in situ polymerization and intimate mixing, respectively. The backbone structure of PDPA in the composite decomposed at a higher temperature (>340°C) than the pristine PDPA (～300°C). This behavior also favored the molecular level interactions between MWNT and PDPA in the composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3721–3729, 2006     

Dissolution rates for thin films of miscible polymer blends

The dissolution rates of thin polymer films were measured and compared. Mixtures of various ratios of poly(methyl methacrylate), PMMA, and poly(p-hydroxystyrene), PPHS, were dissolved in methyl isobutyl ketone, MIBK. The polymer solutions were then spun into thin films on silicon wafers and dried. The coated wafers were immersed in an MIBK bath and the rate of dissolution was observed using laser interferometry. The results show that pure PPHS films have dissolution rates 1000 times greater than films of pure PMMA at comparable molecular weights. However, for films containing both PPHS and PMMA, a minimum dissolution rate occurs for a mixture with about 20% (by weight) PPHS. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2015–2020, 1997