Styrene-methacrylic Acid Copolymer Research Articles

Facile construction of magnetic hydrophilic molecularly imprinted polymers with enhanced selectivity based on dynamic non-covalent bonds for detecting tetracycline

While a number of methods towards water-compatible molecularly imprinted polymers (MIPs) have been reported, new strategies affording simple preparation process and enhanced adsorption selectivity towards templates are needed to promote the further development of MIPs. Herein, we propose a novel method for preparing water-compatible MIPs (Cu-CMMIPs) with enhanced selectivity for tetracycline (TC) based on the dynamic physically cross-linking. The as-synthesized styrene-methacrylic acid copolymer was introduced as hydrophilic cross-linking functional monomers instead of conventional functional monomers and cross-linkers, thus eliminating the need of optimizing the cross-linkers/functional monomers ratio. The copper ions served as cross-linker, and in view of increased adsorption capacity and enhanced selectivity of the prepared MIPs, it was hypothesized that the introduction of copper ions would result in the strong interaction between the polymer network and TC. The imprinting process of TC is carried out by direct physical cross-linking of active groups of TC with functional groups of the polymeric network. The resultant Cu-CMMIPs exhibited excellent hydrophilicity, outstanding adsorption capacity and selectivity towards TC in water. Finally, the developed Cu-CMMIPs were applied as magnetic solid phase extraction adsorbents for the specific recognition of TC in environmental water combined with HPLC-DAD detection (LOD is 3.75 μg/L and the recoveries ranging from 91.2 % to 101.3 %). The proposed concept in this work for fabrication of MIPs with facile preparation process, enhanced selectivity and satisfactory hydrophilicity would inspire more ideas to implement in cost-effective adsorbents construction.

A New Type of Dispersant [Sodium Salt of Styrene–Methacrylic Acid Copolymer (SSMA)/Montmorillonite (MMT) Nanocomposite] for Pesticide Water Dispersible Granules

AbstractA new type of dispersant [sodium salt of styrene–methacrylic acid copolymer (SSMA)/montmorillonite (MMT) nanocomposite] with different content of the MMT was synthesized through in situ solution free radical copolymerization. X‐ray diffraction measurements and electron microscopy observations prove that SSMA molecules can enter the interlayer space of MMT and form an intercalated structure. There are both fully intercalated and partly intercalated structures in the nanocomposites, which are related to the loading content of MMT. Transmission and scanning electron microscopy images indicate that the exfoliation degree of MMT in the nanocomposites decrease with increasing MMT content. Infrared spectroscopy (FTIR) analysis shows that there are hydrogen‐bonding interactions between carboxyl groups of SSMA and hydroxyl groups of MMT. Atrazine water dispersible granules were prepared by using SSMA/MMT nanocomposite as dispersant and their suspensibility in aqueous solution was determined to evaluate the dispersion properties of the nanocomposite. The results show that the addition of MMT can not only increase the steric effect of the SSMA to improve its dispersion properties, but also reduce the production cost of SSMA. The optimum loading content of MMT is 10 wt%.

Preparation and characterization of nanocomposites of natural rubber with polystyrene and styrene-methacrylic acid copolymer nanoparticles

Composites of natural rubber (NR)/vinyl polymer nanoparticles as polystyrene (PS) and poly(styrene- methacrylic acid) (P(S-MAA)) were prepared by heterocoagulation technique. The polymer nanoparticles were prepared by emulsifier-free emulsion polymerizations at 70°C using potassium persulfate as initiator. Under acidic condition where pos- itive charge was present on the NR latex (NRL) surface, the nanoparticles having negative charge mainly from sulfate group of initiator were able to adsorb on the NRL surface, the electrostatic interaction being the driving force. The scanning electron micrographs showed that the polymer nanoparticles are homogenously distributed throughout NR matrix as nano- clusters with an average size of about 500 and 200 nm for PS and P(S-MAA), respectively. The mechanical properties of NR/PS and NR/P(S-MAA) composite films were compared with the NR host. The nanocomposites, particularly when the polymer nanoparticles are uniformly dispersed, possess significantly enhanced mechanical properties strongly depending on the morphology of the nanocomposites.

Effect of stirring on preparation of hollow copolymer particles by alkali/cooling method

Hollow particles were prepared by the treatment of styrene-methacrylic acid copolymer particles with alkali/cooling method. The influences of stirring position (in aqueous phase or at the interface of O/W) and stirring speed (90, 110 and 240 r/min) on the formation of hollow particles were investigated. It is found that the soft stirring in aqueous phase at 90 r/min leads to the formation of monohollow particles, while the violent stirring at the interface of O/W and 240 r/min gives non-hollow products. In contrast, the weak stirring in aqueous phase at 110 r/min results in sterically heterogeneous dispersion of methacrylic acid-rich regions within the original particles, and hence the formation of multihollow particles. Further investigation indicates that the change of stirring efficiency provides a way to tune the diffusion behavior of monomer styrene, and therefore influences the distribution of methacrylic acid units in the original particles as well as the morphology of the treated particles.

Incorporation of nonionic emulsifiers inside styrene–methacrylic acid copolymer particles during emulsion copolymerization

Emulsion copolymerizations of styrene and methacrylic acid with polyoxyethylene nonylphenyl ether nonionic emulsifiers having various hydrophilic–lipophilic balance (HLB) values (13.7, Emulgen 911; 15.5, Emulgen 920; 17.2, Emulgen 931) were performed. The incorporation behavior of the nonionic emulsifiers, comprising polydisperse poly(ethylene oxide) (PEO) chain lengths, inside the particles was investigated. At the completion of the polymerization, the incorporated percentage of the lowest HLB emulsifier was 61%, much higher than that of the highest HLB one (10%). In both polymerizations, the amounts of the incorporated emulsifiers increased with conversion, and shorter PEO chain (i.e., lower molecular weight) components were predominantly incorporated over longer PEO chain components.

Influence of nonionic emulsifier included inside carboxylated polymer particles on the formation of multihollow structure by the alkali/cooling method

The influence of nonionic emulsifier, included inside styrene-methacrylic acid copolymer [P(S-MAA)] particles during emulsion copolymerization, on the formation of multihollow structure inside the particles via the alkali/cooling method (proposed by the authors) was examined in comparison to emulsifier-free particles. It was clarified that the nonionic emulsifier included inside the P(S-MAA) particles eased the formation of multihollow structure.

Preparation of multihollow polymer particles by the alkali/cooling method under partial neutralization conditionsa)

AbstractHeterogeneity in the formation of multihollow structure among submicron‐sized styrene‐methacrylic acid copolymer particles, which were produced by batch emulsion copolymerization, by the alkali/cooling method under partial neutralization of carboxyl groups was investigated. There was a threshold of the acid content to form the multihollow structure. The heterogeneity among the particles was based on the heterogeneity of the acid content among the original particles.

Deformation of solid polymers in a constant magnetic field

The effect of a constant magnetic field on the creep rate is investigated for poly(vinyl butyral), styrene-methacrylic acid copolymer [poly(styrene) + 16 wt % methacrylic acid], poly(methylene oxide), and other polymers. It is demonstrated that the constant magnetic field can variously affect different polymers and that the effect of the magnetic field is enhanced in a particular range of strain rates.

Estimation of the adsorption state of nonionic emulsifier molecules onto styrene-methacrylic acid copolymer particles by in situ 1 H NMR measurements

The adsorption behavior of poly(oxyethylene) nonyl phenyl ether nonionic emulsifier molecules onto polystyrene (PS) and styrene–methacrylic acid copolymer [P(S-MAA)] particles dispersed in D2O was evaluated by in situ 1H NMR measurements at room temperature. The resonance due to the protons of the emulsifier molecules was only observed. Normalized NMR integrals of the resonance due to the protons of hydrophobic groups (nonyl and phenyl groups) and the hydrophilic group, poly(oxyethylene) chain, at a certain concentration of the emulsifier decreased with an increase in the total surface area of the PS particles dispersed in the system. The decrease for the hydrophobic groups was much larger than that for the hydrophilic groups. In the dispersion system of P(S-MAA) particles, ionized carboxyl groups at the particle surface decreased the amount of the emulsifier adsorbed.

Heterogeneity among multihollow polymer particles prepared by the alkali/cooling method under partial neutralization conditions

Heterogeneity in the formation of multihollow structure among styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, by the alkali/cooling method under partial neutralization conditions with potassium hydroxide was investigated. There was a threshold acid content to form the multihollow structure. The heterogeneity among the multihollow particles was based on the heterogeneity of acid contents among the original particles.

Evaporation behavior of water from aqueous dispersions of multihollow particles prepared by the stepwise alkali/acid method

In order to clarify the formation mechanism of multihollow structures inside styrene–methacrylic acid copolymer particles prepared by the stepwise alkali/acid method, which we proposed in 1990, the evaporation behavior of water from aqueous dispersions of the original carboxylated particles and those after the alkali treatment and the stepwise alkali/acid treatments was examined. It is concluded that the particle after the alkali treatment had a number of small water pools inside.

Behavior of nonionic emulsifier molecules on the preparation of nanoparticles from submicron-sized ionized styrene-methacrylic acid copolymer particles by the particle dissolution method

Submicron-sized styrene–methacrylic acid copolymer (92/8 molar ratio) particles dissolved in the presence of polyoxyethylene nonylphenylether nonionic emulsifier under alkaline conditions at 90 °C, resulting in nanoparticles with diameters of about 30 nm. In order to clarify the role of the emulsifier molecules in the dissolution process, 1H NMR measurements were carried out. As the particles swelled, the NMR integrals due to the emulsifier decreased markedly. This indicates that the emulsifier molecules permeated into the inside of the alkali-swelling particles and were adsorbed on the polymer molecules, which supports the formation mechanism of nanoparticles by the particle dissolution method proposed in a previous article.

Effect of molecular weight on preparation of nanoparticles by particle dissolution method from submicron-sized ionized styrene-methacrylic acid copolymer particles in nonionic emulsifier solution

Styrene–methacrylic acid copolymer [P(S-MAA)] (92/8, molar ratio) nanoparticles were prepared by a dissolution of submicron-sized P(S-MAA) particles with various molecular weights in a polyoxyethylene nonylphenylether nonionic emulsifier aqueous solution at pH 13.0 and above 90°C. The latter particles were produced by emulsion copolymerization in the presence of various concentrations of n-octyl mercaptan. The effect of molecular weight on the dissolution behavior was examined at various conditions and using various kinds of the nonionic emulsifier. It was clarified that a decrease in the molecular weight led to the production of the nanoparticles at mild treatment conditions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1461–1464, 1997

Influence of the kind of alkali on the preparation of multihollow polymer particles by the alkali/cooling method

The influence of the kind of alkali (KOH, NH 4 OH, ethanolamine ) in alkali treatment on the formation of multihollow structure within submicron-sized styrene-methacrylic acid copolymer particles by the alkali/cooling method proposed by the authors was examined. The original particles were produced by emulsion copolymerization. The obtained results indicate that there was no great difference in the preparation of the multihollow particles by the method using the three kinds of alkali and support the formation mechanism of multihollow structure proposed previously.

Preparation of nanoparticles by “dissolution” of submicron-sized ionized styrene-methacrylic acid copolymer particles in nonionic emulsifier solution

Styrene-methacrylic acid copolymer (P(S-MAA)) nanoparticles having high Tg were produced by a dissolution of submicron-sized P(S-MAA) particles as follows. Submicron-sized P(S-MAA) particles having various MAA contents were produced by emulsion copolymerization. Secondly, they were treated in a polyoxyethylene nonylphenylether nonionic emulsifier aqueous solution at pH 13.0 and above 90 °C. The nanoparticles having about 30 nm in diameter were only produced from the particles having MAA contents around 7 mol%, and above the contents, they were not produced. It seems to be based on that emulsifier molecules are not adsorbed onto the polymer molecules enough to dissolve them. The effect of MAA content on such a dissolution behavior was examined using seven kinds of different nonionic emulsifiers having hydrophile-lipophile-balance values between 12.2 and 18.2 at various temperatures and initial pH.

Maxwell - Wagner - Sillars relaxations in surface-modified glass-bead polystyrene-based composites

Polystyrene-glass-bead and styrene/methacrylic acid copolymer-glass-bead composites were investigated by dielectric spectrometry in order to study the Maxwell-Wagner-Sillars (MWS) interfacial relaxation. Untreated glass beads and glass beads with various surface coatings were both used in the composites. The interfacial relaxation is used to test for the influence of the surface coating on the blocking nature of the interface. A good agreement is found between the van Beek calculated values of the maximum loss frequencies and the experimental ones. Through this analysis, the use of a coupling agent is shown to improve the trapping of the ions at the interface between the polymer matrix and the glass inclusions. This was especially the case in styrene-methacrylic acid copolymer filled with glass beads coated with a methacrylic silane. The presence of water causes the maximum loss frequency to increase dramatically and is also thought to improve the blocking of the electric charges at the matrix-inclusions interface.

Effect of molecular weight on the production of multi-hollow polymer particles by the alkali/cooling method

The effects of molecular weight, particle diameter and cooling condition on the formation of multi-hollow structure formed within submicron-sized styrene-methacrylic acid copolymer particles by the “alkali/cooling method” proposed by the authors were examined and the formation mechanism was proposed. The original particles were produced by emulsion copolymerization in the presence of n-octyl mercaptan as a chain transfer agent.

Production of submicron-sized multihollow polymer particles by alkali/cooling method

Submicron-sized styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, were changed to those having multihollow structure by treating stepwise the emulsion as follows. First alkali treatment was carried out at higher temperature than the glass transition temperature and subsequently the emulsion was cooled by keeping it at room temperature. This was named “alkali/cooling method”. The effects of methacrylic acid content, pH, time and temperature in the alkali treatment on the formation of multihollow structure were clarified.

Production of submicron-sized multihollow polymer particles having high transition temperatures by the stepwise alkali/acid method

Submicron-sized multihollow styrene-methacrylic acid (92.6/7.4, molar ratio) copolymer particles having high transition temperature above 100°C were produced by using the stepwise alkali/acid method proposed by the authors. The original particles were prepared by emulsion copolymerization of styrene and methacrylic acid. The effects of pH, temperature and time in the alkali treatment process as the first step on the multihollow structure were clarified under the same acid treatment conditions.

Water-based epoxy-acrylic graft copolymer

High molecular weight epoxy resins have been grafted with styrene−methacrylic acid monomers; the epoxy-g-(styrene-methacrylic acid) copolymer was water-reducible when neutralized with a base. Characterization of graft sites in the epoxy-g-acrylic copolymer by 13C NMR spectroscopy is described. Grafting takes place at the aliphatic carbons of the epoxy resin. The rationale for this behavior is presented.