Styrene-methacrylic Acid Copolymer Research Articles

Thermal degradation of styrene-methacrylic acid copolymers

Copolymers of styrene and methacrylic acid (MAA) with widely differing compositions have been studied by thermal volatilisation analysis (TVA) and thermogravimetry. The condensable volatile degradation products have been identified after separation by subambient TVA. The cold ring fraction (tar/wax products) and the structural changes in the residue in the course of degradation have also been examined. The copolymers are intermediate in stability between polystyrene (PS) and poly(methacrylic acid) (PMAA). The degradation products are mainly those expected by comparison with those obtained from the homopolymers, but methacrylic acid is formed in greater amount in the copolymer degradation and the distribution of MAA units leads to less intramolecular dehydration. Anhydride rings formed, however, reduce the zip length of depolymerisation to monomers, and both rings and isolated MAA units reduce the possibilities for transfer by polystyryl radicals.

Immunological agglutination kinetics of latex particles with physically adsorbed antigens

The influence of the properties of antigens and particles on the immunological agglutination kinetics of the antigen-coated latex particles was studied. Horse cytochrome c, hen egg-white lysozyme (HEL), bovine serum albumin (BSA), and Aspergillus sp. glucose oxidase were physically adsorbed onto the surfactant free latices of styrene-methacrylic acid (MAA) copolymer (p(S/MAA)) and polystyrene (PS). The initial rates of the immunological agglutination of these protein-coated particles initiated by the addition of antibodies were quantified by the absorbance change at a wavelength of 680 nm. The initial agglutination rates of the particles covered with smaller antigens were lower. This effect of the molecular size of antigens was larger in P(S/MAA), because small antigens are probably buried in the hydrous polymethacrylic acid layer on the surface of particles. Thus, both the molecular size of antigens and the surface properties of particles affect the sensitivity of the immunological agglutination. On the other hand, the dependence of the initial rate of the immunological agglutination on the ionic strength and pH was similar irrespective of antigen-particle systems. The initial agglutination rates were largest at an ionic strength of approximately 0.05 at pH 7.0 and decreased with increasing pH. This dependence of the sensitivity on the pH and ionic strength is attributed to the electrostatic interactions of particle-particle and antibody-particle.

Solution properties of ionomers. I. Counterion effect

AbstractThe effect of counterions on the solution properties of two types of ionomers, one based on sulfonated polystyrene and the other based on styrene–methacrylic acid copolymer, was studied by viscosity and light scattering measurements. It was found that the order of counterion binding of ionomers in a polar solvent and the order of aggregation of ionomers in a low‐polarity solvent were the same for the same ionomer system. However, the order for the sulfonated ionomer was Li < Na < K < Cs, whereas that for the carboxylated ionomer was the opposite. This can be explained by a difference in desolvation during anion–cation interaction and by considering site‐binding in a polar solvent and the association of ion pairs in a low‐polarity solvent. These findings for ionomer systems are parallel to the association behavior of small ions in water, cation affinity in crosslinked resins, and counterion binding of polyelectrolytes in water.

Ion clustering in styrene-based ionomers: Calorimetric and gravimetric hydration studies and effect of ion concentration and thermal history

Abstract : The water sorption behavior of styrene-methacrylic acid copolymers and of their sodium salts has been studied as a function of concentration of ionic groups and nature of the sample. The influence of thermal history has also been examined. The salt forms of the copolymers were found to have a greater hydration capacity than the acids, the hydration capacity increasing with ion content for the salts. The hydration energy of the acid forms was found to be in the vicinity of the liquefaction energy of water whereas the energy for the salt forms became much lower than that value, with increasing water content. This decrease in energy has been attributed to a rearrangement of the cluster structure to accommodate more water molecules.

Preparation and properties of trypsin chemically attached to EEDQ activated styrene–methacrylic acid copolymers

Styrene-methacrylic acid copolymers of varying combinations crosslinked with p-DVB (1-2%) and porous structure were synthesized to be used as carriers in trypsin immobilization. The styrene-methacrylic acid copolymers containing free carboxy groups were activated by conversion into the mixed carbonic anhydride with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) at pH 4.0. The degree of activation of copolymers were determined from the amount of p-aminobenzoic acid each could bind. The activated copolymers were incubated with trypsin in phosphate buffer (pH 8.0) at 4 degrees C for 24 h. The optimum conditions for enzymatic activity measurements determined and the activity tests were carried out in 1.5 x 10(-2)M CaCl(2) solution (pH 8.0) at 0.05 ionic strength with a pH-stat instrument. The dependence of the activity of styrene-methacrylic acid (SMA)/trypsin derivatives to pH was investigated and it was observed that the optimum pH of the immobilized trypsin derivatives moved to the basic region compared to the native trypsin. It was found that as the ionic strength increased, the shift in the optimum pH decreased and the activity increased. The Michaelis constants for the SMA-trypsin derivatives were determined with aid of Lineweaver-Burk diagrams. The thermal, storage, and operational stabilities of SMA-trypsin derivatives were assessed. It was found that the above stabilities for all the immobilized trypsin derivatives were better than that for the native trypsin.

Dielectric Relaxations of Ethylene–Acrylic Acid and Styrene–Methacrylic Acid Copolymers and Their Sodium Salts

Dielectric Relaxations of Ethylene–Acrylic Acid and Styrene–Methacrylic Acid Copolymers and Their Sodium Salts

Resistance to deformation and intermolecular interaction in glassy polymers

With polystyrene and styrene-methacrylic acid copolymers, the relationship between the resistance to non-elastic formation and the effective energy of the specific (hydrogen bonds) and the van der Waals (universal) intermolecular interactions has been experimentally investigated. The stress-strain curves σ(ϵ) have been compared with the corresponding changes in the intermolecular interactions. The latter have been varied by alteration of the copolyner composition, by quenching and by deformation and have been assessed by IR spectroscopy and differential scanning calorimetry. It has been demonstrated that there is a direct connection between the change in the resistance to deformation and the change in the energy of intermolecular interaction. For a series of polymers investigated with similar structures, the limit of enforced elasticity, σ B, has been found to depend linearly on the effective energy of intermolecular interaction.

Dielectric properties and conductivity of styrene-methacrylic acid copolymers and partially neutralized salts

Abstract Dielectric and conductivity measurements have been carried out on styrene-methacrylic acid copolymers and their salts in the glass transition region, stressing the comparison of polymers neutralized to different extents. A simple monomer-dimer equilibrium between carboxylic acid groups is applicable to the pure acid polymers, which explains the increase of both the glass transition temperature and of the dielectric strength with concentration of methacrylic acid. The dielectric data indicate that very few sodium carboxylate groups can dissolve in the matrix of the pure salt, whereas the presence of carboxylic acid groups in partly neutralized polymers enhances the dissolution of the salt groups in the matrix. Considerable differences are observed between the partly neutralized polymer and the blend consisting of pure acid and pure salt copolymers, which suggests that exchange of cations between acid and salt groups is quite slow even at high temperatures. The conductivity of the ionomers appears to be related to the diffusion of carriers through the matrix.

Dielectric relaxations of Cu(II) salts of ethylene—acrylic acid and styrene—methacrylic acid copolymers

Dielectric constant, ɛ′, and the loss, ɛt", of various Cu(II) salts of ethylene-acrylic acid, E-AA, (9.3 mol% AA) and styrene-methacrylic acid, S-MAA, (4.4 mol% MAA) have been measured in the frequency range of 30 Hz to 30 kHz. In the Cu(II) salts of E-AA which form almost dimeric structure of monohydrated copper acetate, two relaxations were observed, β'-relaxation due to a micro-Brownian molecular motion aboveT g andy-relaxation due to a local molecular motion belowT g . By examining molecular motion and estimating number of polar group for the two relaxations, an existence of ion aggregation was comfirmed at the high degrees of neutralization above 20%. In the Cu(II) salts of S-MAA, there were three types of structure of copper complex, monomeric type, monohydrated copper acetate type and pseudo anhydrous copper formate type, the mixing ratio of which depends on preparation procedure of Cu(II) salts. Dielectric behavior of y-relaxation was sensitively influenced by the structure of Cu(II) salt.

Molecular interaction and conformation of molecules in polystyrene and styrene-methacrylic acid copolymers

A study was made of universal and specific molecular interaction (MI) and the conformation structure in solid PS and styrene-methacrylic acid (MAA) copolymers, the content of the latter acid varying between 2 and 33 mole %. Experiments were carried out by IR spectroscopy using results of differential scanning calorimetry (DSC) and internal friction (IF). A spectroscopic parameter was selected for the control of variations of universal MI in the polymers studied. Hydrogen bond concentrations in the copolymers were determined according to composition and past thermal history. It was found that in addition to the main effect-increase in the entire MI as a result of hydrogen bonds, the addition of MAA units to PS produces secondary effects, a reduction in universal MI, increase in small scale mobility and chain convolution. These effects are particularly significant starting from MAA concentrations of 10–16%, when average distances between hydrogen bridges become commensurate with the size of the statistical segment.

The use of differential scanning calorimetry for evaluating the intermolecular reaction changes in glass-like polymers

The possibility of using differential scanning calorimetry to study the intermolecular reactions in polymer glasses has been tested experimentally. Polystyrene and the styrene-methacrylic acid copolymer have been used to show the effects of the composition (structure), the thermal and mechanical history on the progress of the differential scanning calorimetry (DSC) curve. The respective energy changes (enthalpy differences ΔH) appearing on the curves in the relaxation transition ranges have been evaluated. The results have been compared with the inter- and intra-molecular reaction changes established by IR spectroscopy. The DSC was found to be useable in a quantitative evaluation of the intermolecular reactions taking place in polymer glasses.

Studies on preparation and stability of styrene-methyl methacrylate and styrene -methacrylic acid copolymer latices

Series of styrene-methyl methacrylate (SM) and styrene-methacrylic acid (SA) copolymer latices have been prepared by emulsion polymerization using polyoxyethylene nonyl phenyl ether as emulsifier and potassium persulphate as initiator. Trace carboxyl groups were detected both in polystyrene latex and styrene-methyl methacrylate copolymer latices. The stability and electrophoretic behaviour of these latices against barium chloride have been investigated. The values of the critical coagulation concentration (c. c. c.) increased with increasing methacrylic acid content for SA series latices, while they are almost independent of methyl methacrylate content for SM series latices. The effects of methyl methacrylate and methacrylic acid on the change in Hamaker constant were found to be almost identical. The difference inc. c. c. between SM and SA series latices seems to be due to the difference in electrical repulsion caused mainly by carboxyl groups on the surface.

Rheogoniometry of molten blends of polystyrene and styrenic ionomers

AbstractThe rheological properties of the molten blends between polystyrene (PS) and styrenemethacrylic acid copolymer (S‐MAA) or its metallic salts were determined with a Weissenberg rheogoniometer, and the mixed structure and the processability were discussed. Results were as follows. (1) The viscosities of the salts increased and the compliances decreased with increasing density of ionic crosslinkings. (2) The viscosities of the molten blend between PS and S‐MAA or its salt increased steeply even at lower shear rate and the Newtonian flow region was not observed. (3) This shear‐sensitivity of viscosity in low shear rate region increased with increasing temperature. (4) The effect of temperature on the viscosity of these blends deviated from the simple Arrhenius plot. (5) Some network structures are suggested for the blends between PS and S‐MAA salts but they may be broken eventually under high shear rate or at high temperature. Therefore, the mixed structures and the flow mechanisms of these molten blends seem to change with shear or temperature.

Preparation and characterisation of styrene—methyl methacrylate and styrene–methacrylic acid copolymer latices

AbstractSeries of styrene‐methyl methacrylate and styrene‐methacrylic acid copolymer latices have been prepared by emulsion polymerisation using polyoxyethylene nonyl phenyl ether as emulsifier and potassium persulphate as initiator. the effects of surfactant concentration and monomer composition on the ultimate particle size and conversion were investigated. The ultimate particle diameters decreased with increasing surfactant concentration, while the conversions were found to be almost independent of surfactant concentration. The ultimate particle diameters were notably decreased by increasing the content of methacrylic acid. Trace carboxyl groups were detected both in polystyrene latex and styrene‐methyl methacrylate copolymer latices. The number of sulphate groups on the polystyrene latex surface was about five times that of carboxyl groups.

Studies on polymer blend of nylon 6 and polypropylene or nylon 6 and polystyrene using the reaction of polymer

AbstractIn the presence of maleic anhydride‐grafted polypropylene, marked dispersibility of the polymer blend of isotactic polypropylene and nylon 6 was obtained. This appeared to be caused by the formation of a certain graft polymer between maleic anhydride in polypropylene and terminal amino groups of nylon 6. The same phenomenon was observed when polystyrene and nylon 6 were blended with styrene–methacrylic acid copolymer as the interpolymer. The existence of such a graft polymer was confirmed by solvent extraction, estimation of the amino group of nylon 6, and identification by differential scanning calorimetry. The physical properties, especially mechanical properties of nylon 6–polypropylene polymer blends, were remarkably improved with increase of maleic anhydride added to the polymer blend. On the other hand, the physical properties those of nylon 6–polystyrene polymer blends were very little improved even in the presence of good dispersibility.

Infrared Spectroscopic Approaches to Polymer Transitions. II. The Transition of Hydrogen Bonding in Styrene–Methacrylic Acid (St–MAA) Copolymers

Recently, infrared spectrophotometry has been applied as a useful tool for the investigation of polymer transitions. The solid-state transition in styrene–methacrylic acid copolymer was studied by infrared method in the range of 23–170°C. From the temperature dependence of the peak absorbances of 1700- and 1745 cm−1 bands, transition at 120°C was detected, and its mechanism was presumed to be associated with the association-dissociation process of intermolecular force between chains, namely with the breakdown of intermolecular hydrogen bonding. These results are in good agreement with Andrews’ definition for polymer transitions (or Tg). Thus the transition at 120°C was interpreted by the normal thermodynamic equilibrium consideration.

Polymer association. V. Solution behavior and rheology of neutralized styrene-methacrylic acid copolymers

The behavior of styrene copolymers containing 2.3 mole % or 5.6 mole % of methacrylic acid and of their lithium, sodium, and barium salts was studied in dilute benzene and dioxane solution. Light-scattering molecular weights were higher in benzene but the extent of molecular aggregation was small except with the barium salt. Intrinsic viscosities of the acid polymers and their salts were very similar but the reduced viscosities of the salts increased rapidly at concentrations above 1 g./100 ml., suggesting an increasing molecular association. Creep and creep recovery studies were carried out on films containing styrene copolymer with 2.3 mole % methacrylic acid, its lithium and barium salt, and a styrene homopolymer of similar chain length, all plasticized with 25% dioctyl phthalate. The rigidity and the tensile viscosity increased as the forces between interacting groups were increased in the order — COOH < —COO −Li + < —COO −Ba ++ 1 2 , but when the materials were compared at temperatures corresponding to the same compliance, the irrecoverable flow was least with samples which had the strongest interacting groups. The activation energy of viscous flow changed in an order opposite to that of the tensile viscosities. Films plasticized with an α-methylstyrene oligomer were more rigid and had less irrecoverable flow than films plasticized with DOP. This difference was much more pronounced with the acid copolymer than with its lithium salt.