Pore memory of macroporous styrene–divinylbenzene copolymers

The variation of the pore structure of styrene–divinylbenzene (S–DVB) copolymer beads with the drying conditions was investigated. Macroporous S–DVB copolymer beads with various DVB contents were prepared in the presence of toluene‐cyclohexanol mixtures as a diluent. It was found that the pores of 10¹‐nm radius, corresponding to the interstices between the microspheres, collapse upon drying of the copolymers from toluene. The collapsed pores reexpand if the copolymers were dried from methanol. The collapse–reexpansion process of the pores was found to be reversible, indicating that the actual pore structure formed during the crosslinking copolymerization is memorized by the copolymer network. The magnitude of the pore structure variation increased on worsening the polymer–diluent interactions during the gel formation process due to the simultaneous increase in crosslink density distribution. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1055–1062, 1999     

共聚原甲基丙烯酸酯系吸附功能树脂合成及其性能研究

采用悬浮聚合法合成了LMA(甲基丙烯酸十二酯)均聚树脂、BMA(甲基丙烯酸正丁酯)/LMA共聚树脂、BMA/HEMA(甲基丙烯酸( 羟乙酯)共聚树脂、BMA/DVB(二乙烯基苯)共聚树脂以及BMA/HEMA/LMA共聚树脂.研究了单体种类、交联剂种类以及用量与树脂吸附性能、交联密度间的关系,利用FT-IR对树脂试样的化学结构进行了表征.结果表明,与LMA均聚物相比,BMA被引入大分子主链后,BMA/LMA共聚树脂对煤油的吸附量大大降低,对甲苯和三氯乙烯的吸附量增大,而BMA/LMA/HEMA共聚树脂对煤油、甲苯和三氯乙烯的吸附量均有所下降;化学交联型树脂的吸附量随时间变化较小,物理交联型树脂其吸附量随时间变化较为明显;物理交联剂HEMA的质量分数影响树脂的三维网状结构,进而影响树脂的吸附性能;树脂大分子间存在氢键作用,有利于物理交联结构的形成,长侧链LMA结构单元的引入,促使侧链间发生缠结甚至结晶,进一步增强了物理交联结构.     

Preparation and properties of poly(butyl methacrylate/lauryl methacrylate) and its blend fiber

The functionalized copolymers, based on butyl methacrylate (BMA), and lauryl methacrylate (LMA) with crosslinking agent HEMA (hydroxyethyl methacrylate) or DVB (divinyl benzene), have been innovatively synthesized by suspension polymerization for oil absorption. Further, the copolymers and polypropylene (PP) blend fiber were attained via melt spinning. Swelling behaviors were evaluated by equilibrium swelling experiment, oil absorbency test, gel fraction measurement, and optical observations in toluene. The thermal properties and morphologies of the blend fibers were analyzed by thermogravimetry (TGA) and a field-emission scanning electron microscope, respectively. The results show that the copolymers and their blend fibers have an impressive absorbency. PBMA/LMA/HEMA can be up to 35.18?g/g, showing the highest absorption in trichloroethylene. Optical images of swollen polymers in toluene depicted a colloidal translucence with gel structure. Thermogravimetric measurement demonstrates that the copolymer and PP are incompatible and PBMA/LMA/DVB component possesses more thermal stability. The micrographs of the blend fibers exhibit coarse surface and porous cross-section, which leads to the fibers being much more readily wetted by oil and provides a huge space for oil storage.     

Studies of crosslinked styrene–alkyl acrylate copolymers for oil absorbency application. I. Synthesis and characterization

The prepolymers for a novel oil absorbent were synthesized by copolymerizing styrene with 2‐ethylhexyl acrylate (EHA), lauryl acrylate (LA), lauryl methacrylate (LMA), and stearyl acrylate (SA). Suspension polymerization was carried out using benzoyl peroxide (BPO) as an initiator with a varying monomer feed ratio, and the copolymers were characterized by FTIR, ¹H‐NMR, DSC, and a solubility test. The copolymers were random copolymers with a single phase, and their compositions were similar to those in the monomer feed. The T_g of the copolymer could be controlled by varying the styrene/acrylate ratio. Acrylates introduced the crosslinking to linear polymers as a side reaction. Crosslinked copolymers were synthesized by adding divinylbenzene (DVB) as a crosslinking agent. At a low degree of crosslinking (0.5 wt % DVB), the T_g of the crosslinked copolymers was lower than or similar to that of the uncrosslinked ones. At a high degree of crosslinking, the T_g increased with increasing crosslinking density. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 903–913, 2000     

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     

Turbidimetric determinations of theta compositions

The turbidimetric titration method of determining theta conditions developed by Elias and modified by Cornet and van Ballegooijen has been extended and generalized for different types of polymer–solvent–nonsolvent systems. The modified procedures for the determination of theta compositions have been verified with the following systems: polystyrene–cyclohexane–n-hexane, polystyrene–cyclohexane–n-butanol, and polystyrene–toluene–nonsolvent.     

Porous maleic anhydride–styrene–divinylbenzene copolymer beads

The formation of the porosity and the pore stability in maleic anhydride–styrene–divinylbenzene (MAn–St–DVB) copolymer beads were investigated using the apparent density measurements of the samples dried from methanol (maximum porosity) and from dioxane (stable porosity). The copolymer beads were prepared by the suspension polymerization method in glycerol instead of water as the dispersing medium. A toluene–dioxane (1:1) mixture was used as the diluent at a fixed volume fraction of the organic phase (0.47). Compared to St–DVB copolymers prepared in the presence of nonsolvating diluents, porous MAn–St–DVB copolymers are obtained at relatively low DVB concentration, i.e., at 1–3% DVB. The porosity of the copolymers increases with decreasing MAn concentration in the feed due to the decrease in the copolymer yield. The results of the elemental analyses and titrimetric methods indicate that approximately only half of the MAn units in the copolymer are able to react with amine or with water. A possible rearrangement of the MAn units into the cyclopentanone structures was suggested.     

Pore structure and water‐swelling behavior of porous resins based on methyl acrylate and different divinylbenzene isomers

Porous resins based on divinylbenzene (DVB) and methyl acrylate (MA) were prepared with m‐DVB (98.3%) or p‐DVB (99.1%) in the presence of toluene as a porogen. The MA/DVB resins thus obtained with a wide range of pore structures were hydrophobic in nature and were swellable by direct contact with water. The behavior of m‐DVB and p‐DVB as a crosslinker in the MA/DVB monomer system was different from that in the styrene (ST)/DVB system and was influenced by the amount of MA in the MA/DVB monomer system. As a result, a larger specific surface area and pore volume were observed for MA/DVB resins derived from p‐DVB than for those derived from m‐DVB, which was opposite to that observed for resins based on DVB and ST. The different behaviors of m‐DVB and p‐DVB in the MA/DVB monomer system also resulted in different swelling abilities of the resins in water. Compared with the MA/DVB resins derived from m‐DVB, the p‐DVB derived resins swelled faster in water and were water‐swellable when the resins had a higher DVB content and, therefore, a stronger hydrophobicity and a larger specific surface area. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2071–2078, 2005     

Solvent effect on the emulsion copolymerization of methyl methacrylate and lauryl methacrylate in aqueous media

Aqueous emulsion homo- and copolymerization of lauryl methacrylate (LMA), a highly hydrophobic, almost water-insoluble monomer, is quite challenging. Due to the addition of ethanol to the aqueous phase the solvency for LMA is increased and it is possible to successfully produce LMA-methyl methacrylate (MMA) copolymer particles. The incorporation of LMA is confirmed by ¹H NMR spectroscopy. Coagulation at higher ethanol content in the continuous phase could be avoided by polymeric steric stabilizers such as poly(vinyl pyrrolidone) or poly(vinyl alcohol). The conversion–time curves exhibit, independent of the stabilizer, an initially high rate where predominantly MMA is polymerized and a second period with slower rate dominated by LMA consumption as proven by ¹H NMR spectroscopy and DSC data. The morphology of the copolymer particles changes with increasing ethanol content from solid sphere - like to porous. For medium PVP - stabilizer concentrations the particles possess a single pore and appear almost bowl-shaped. The large difference between the hydrodynamic and the hard sphere particle diameter indicates a high degree of swelling of the copolymer particles with the water–ethanol mixture of the continuous phase.     

Metal‐solvating and self‐association of amphiphilic polyamides containing poly(oxyethylene) blocks

An amphiphilic poly(ether amide) consisting of hydrophilic poly(oxyethylene) amide blocks was prepared from the copolymerization of sebacic acid and two poly(oxyalkylene) diamines including a poly(oxyethylene) diamine (POE‐amine at 2000 M_w) and a poly(oxypropylene) diamine (POP‐amine at 230 M_w). The copolymer was estimated to have an average molecular weight of 15,000 M_w (GPC) or approximately three hydrophilic POE segments per strain. The presence of POE segments rendered polymer hydrophilicity and complexing ability for Li⁺, K⁺, Ca⁺², Ni⁺², Pd⁺², and Cu⁺² salts. In particular, lithium perchlorate affected the copolymer to the greatest extent in enhancing electrostatic dissipation or reducing surface resistivity as low as 10^5.0 Ω/sq (cross‐sectional area) at 1/180 Li⁺/EO from 10^7.2 Ω/sq (without metal ion). In such a metal complexation, the copolymer showed a new POE segmental crystalline phase at a melting temperature between ?10.4 and ?14°C, accompanied with the metal‐free original phase of ?31°C. In static toluene/water, the metal ions had no effect on the copolymer surfactancy in lowering the interfacial tension, reaching 4.4 dyn/cm at a critical micelle concentration (cmc) of 0.01 wt %. When mixing toluene and water, the lithium or nickel ions were found to be detrimental to the emulsifying process. Without the metal ion, fine droplets at average sizes of 4.5–5.0 μm were observed in the copolymer/ toluene/water emulsification. These amphiphilic behaviors of the POE‐segmented polyamide with or without metal ions were explained by the competing noncovalent bonding interactions among POE/metal ion/water. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 612–621, 2002     

Preparation of highly syndiotactic block copolymers of methyl methacrylate and lauryl methacrylate and their characterization

Summary Highly syndiotactic diblock and triblock copolymers comprising lauryl methacrylate (LMA) and methyl methacrylate (MMA) with narrow molecular weight distributions were prepared by the living anionic polymerization with t-C₄H₉Li/(C₂H₅)₃Al in toluene at low temperature. The block copolymers were soluble in acetone which is a non-solvent for poly(lauryl methacrylate) (PLMA). ¹HNMR and vapor pressure osmometric analyses of the block copolymers indicated the aggregation of the copolymer in acetone through the interaction between PLMA blocks. Stereocomplex formation between the triblock copolymer and isotactic poly(methyl methacrylate) (PMMA) took place more effectively in solution than in the solid state.     

Particle size and distribution of biodegradable poly‐D,L‐lactide‐co‐poly(ethylene glycol) block polymer nanoparticles prepared by nanoprecipitation

A biodegradable block copolymer, poly‐D ,L ‐lactide (PLA)‐co‐poly(ethylene glycol) (PEG), was prepared by the ring‐opening polymerization of lactide with stannous caprylate [Sn(Oct₂)] as a catalyst; then, the PLA–PEG copolymer was made into nanoparticles by nanoprecipitation under different conditions. The average molecular weight and structure of PLA–PEG were detected by ¹H‐NMR and gel permeation chromatography. The sizes and distributions of the nanoparticles were investigated with a laser particle‐size analyzer. The morphologies of the nanoparticles were examined by transmission electron microscopy. The effects of the solvent–nonsolvent system, operation conditions, and dosage of span‐80 on the sizes and distributions of the nanoparticles are discussed. The results show that acetone–water was a suitable solvent–nonsolvent system and the volume ratio of the nonsolvent phase to the solvent phase (O/W) (v/v), the concentration of PLA–PEG in the solvent phase, and the dosage of span‐80 had important effects on the particle sizes and distributions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1884–1890, 2005     

Antibacterial activity of resin-containing triethylenetetramine side chains and/or thiol groups–metal complexes

Four chelating resins containing triethylenetetramine side chains and/or thiol groups were made from macroreticular 2,3-epithiopropyl methacrylate, styrene–divinylbenzene (DVB), or methyl methacrylate–DVB copolymer beads, and then the resins bearing metal ions such as Ag⁺, Cu²⁺, and Zn²⁺ were made. The antibacterial activity of the resins bearing metal ions against Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) was investigated. The resins containing thiol groups showed the higher adsorption capacity for silver ions than for other metal ions. The resins, which contain both triethylenetetramine side chains and thiol groups, bearing silver ions (RE-TTA-Ag) exhibited high antibacterial activity against bacteria, especially E. coli, without the residual silver ions in water after contacting with bacteria. The activity of the RE-TTA-Ag did not decrease even after reusing several time. © 1996 John Wiley & Sons, Inc.     

Synthesis of 100 μm uniform porous spheres by SPG emulsification with subsequent swelling of the droplets

100 μm porous p(styrene-co-divinylbenzene) (PS-DVB) microspheres were synthesized by employing a particular membrane emulsification technique, and subsequent swelling of the seed droplets. DVB dissolving a water-insoluble substance, hexadecane (HD), and an initiator was permeated through a SPG (Shirasu porous glass) membrane, and the uniform (seed) droplets were released to a stabilizer solution acting as the continuous phase. The average droplet size was around 30 μm, and this emulsion was mixed with a secondary emulsion of much smaller size consisting of more hydrophilic components, a mixture of styrene, middle chain alcohol (C6 to C8), dichlorobenzene, and isoamyl acetate, which promotes the degradative diffusion process of the components. After all the droplets in the secondary emulsion virtually disappeared, the seed droplets were swollen to a maximum 110 μm. Polymerization was carried out at 348 K under a nitrogen atmosphere. Uniform porous spheres of 100 μm with the coefficient of variation less than 10% were obtained. Specific surface area was 350 m²/g. Careful controlling of the specific gravity of swollen droplets and the choice of solvents balancing between the good solvency for the polymer and polarity (solubility in water) proved vital in order that the polymerization may proceed without an extensive phase separation in the early stage, which eventually induces breakup of the droplets. The three component system, isoamyl acetate-hexanol-o-dichlorobenzene, provided an adequate cosolvent for these purposes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 931–942, 1997     

Studies of porous polymer gels. II. Structure and porosity of moderately crosslinked poly(methacrylic acid) gels

The porosity of suspension copolymers of methacrylic acid (MA) and divinylbenzene (DVB) has been studied. The copolymers were prepared both directly from monomer blends and with toluene or n-octane as inert diluents. The pore volume and radii of pores were larger for copolymers containing 5.0% of DVB than those for copolymers containing 9.1% of DVB. The volume and radii of pores increased with increasing diluent content, but the effect of n-octane was more pronounced than that of toluene. Based on considerations of monomer reactivities and copolymer-diluent and copolymer-unreacted monomer interactions, the following model of structure of MA and DVB copolymers has been proposed: The copolymers are composed of microgels interconnected into a rigid skeletonlike structure, surrounded by lightly crosslinked and unentangled poly(methacrylic acid) chains.     

Translucent acrylic nanocomposites containing anisotropic laminated nanoparticles derived from intercalated layered silicates

New acrylic nanocomposites consisting of methyl methacrylate (MMA)/n‐dodecylmethacrylate (LMA) copolymers and intercalated layered silicates were prepared. The silicates were based upon bentonite which was rendered organophilic by ion exchange with N,N,N,N,‐dioctadecyl dimethyl ammonium ions. Morphological, thermal, mechanical, and optical properties were examined as a function of both organophilic bentonite and LMA content. Addition of LMA improved the compatibility between the layered silicate and the acrylic matrix, thus promoting bentonite intercalation and formation of anisotropic laminated silicate nanoparticles of an average diameter of 18 nm, average length of 450 nm, and interlayer distance of 4.8 nm, as determined by WAXS, TEM, and AFM. Addition of 2–10 wt % of intercalated layered silicate accounted for improved stiffness/toughness balance, higher glass temperature, and enhanced thermal stability, with respect to the properties of the corresponding MMA/LMA copolymer. As a result of the addition of LMA, translucent acrylic nanocomposites were obtained. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 396–405, 2000     

Miniemulsion polymerization of styrene with polymeric costabilizers

The polymeric costabilizers poly(stearyl methacrylate‐co‐2‐hydroxyethylmethacrylate) (PSH) and poly(lauryl methacrylate‐co‐2‐hydroxyethylmethacrylate) (PLH), composed of a hydrophilic backbone and several hydrophobic alkyl (stearyl or lauryl) side chains, were prepared by the free‐radical copolymerization of stearyl methacrylate (SMA) or lauryl methacrylate (LMA) with 2‐hydroxyethylmethacrylate and evaluated in the miniemulsion polymerization of styrene (ST). For comparison, the reactive costabilizers SMA and LMA were also included in this work. The hydrophobicity of costabilizers in increasing order was PLH < PSH < LMA < SMA. Only a small amount of these comb‐like copolymers was capable of producing kinetically stable ST emulsion droplets. The more hydrophobic the costabilizer was, the more effective was the costabilizer in the retardation of Ostwald ripening. About 30–40% of the monomer droplets were successfully converted into latex particles during the polymerization. The degree of monomer droplet nucleation increased with increasing hydrophobicity of the costabilizer. The formation of particle nuclei in the continuous aqueous phase played a crucial role in the polymerization kinetics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1961–1969, 2004     

Synthesis and properties of natural rubber modified with stearyl methacrylate and divinylbenzene by graft polymerization

The graft polymerizations of stearyl methacrylate (SMA) and divinylbenzene (DVB) onto natural rubber (NR) were carried out in a solution process using benzoyl peroxide (BPO) as an initiator in toluene or chloroform. The main products of the grafted NR include an uncrosslinked (sol) part [sol(SMA–NR–DVB): s‐SNRD] and a crosslinked (gel) part [gel(SMA–NR–DVB), g‐SNRD]. s‐SNRD was obtained by extraction using tetrahydrofuran. It was identified by IR and ¹H‐NMR spectroscopies. The glass transition temperature (T_g) and thermal properties of s‐SNRD and g‐SNRD were studied by DSC and TGA. The glass transition temperature and thermal decomposition temperature of s‐SNRD and g‐SNRD were higher than were those of NR. The light resistance and weatherability of s‐SNRD were measured with a Weather‐o‐Meter. The light resistance and weatherability of s‐SNRD are better than are those of NR. The effects of the initiator concentration, mol ratio of SMA to DVB, reaction time, temperature on grafting ratio, and crosslinking ratio were investigated. The highest grafting ratio and crosslinking ratio in the graft polymerization of SMA and DVB onto NR were obtained when the mol ratio of SMA to DVB and BPO were 4.0 and 2 wt %, at 80°C for 48 h, respectively. Following several studies on oil‐absorptive polymers in our laboratory, 9 the oil absorptivity of g‐SNRD was examined using crude oil. The oil absorptivity of g‐SNRD was 600% when the immersion time was 10 min. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2464–2470, 2001     

Design and preparation of cross‐linked α‐methylstyrene acrylonitrile copolymer nanoparticles and their interfacial investigation with rubber

Cross‐linked α‐methylstyrene and acrylonitrile (MStAN) copolymer particles in a latex form were synthesized by free radical emulsion polymerization. The particles showed a narrow size distribution and an average diameter of 65 nm. The amount of the vinyl groups at the surface of the (MStAN) copolymer particles resulted from varied amount of the initiator (APS) and the cross‐linking agent (DVB) was detected by iodine titration method. When filled into ethylene propylene rubber (EPR), the MStAN nano‐particles exhibited excellent reinforcing capabilities, and with the increase of the vinyl groups at the surface of MStAN particles, the tensile stress of MStAN/EPR increased. Results demonstrated that the vinyl groups at the surface of the (MStAN) copolymer particles provided certain chemical interactions between the filler particles and the macromolecular chains of rubber matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41914.     

Preparation of Chelating Resins Containing a Pair of Neighboring Carboxylic Acid Groups and the Adsorption Characteristics for Heavy Metal Ions

Abstract

For the functional enhancement of chelating resins containing carboxylic acids, copolymer beads were prepared by suspension polymerization of styrene (St), methyl methacrylate (MMA), and divinylbenzene (DVB) in the presence of toluene as diluent. The phenyl rings of the beads were directly chloromethylated, and the carboxylic ester groups of the beads were converted into hydroxymethyl groups by reduction followed by chlorination to give chloromethyl groups, respectively. The chelating resins containing a pair of neighboring carboxylic acid groups (NCAGs) were obtained by the alkylation of chloromethyl groups in copolymer beads with diethyl malonate in the presence of sodium hydride followed by hydrolysis using aqueous alkali solution. Accordingly, the structural effects of the resins on the adsorption of heavy metal ions were investigated. Poly(St‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, and Cu²⁺, whereas poly(MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Cu²⁺, Cd²⁺, and Co²⁺. On the other hand, poly(St‐co‐MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, Co²⁺, and Cu²⁺: a synergistic effect on the adsorption of heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, and Co²⁺ was observed. The adsorption ability of poly(St‐co‐MMA‐co‐DVB)‐based chelating resin among three kinds of chelating resins was relatively good.