Copolymers Of Sodium Research Articles

Solvent Effects in the Synthesis of Highly Charged Foams of Poly(4‐styrenesulfonate‐co‐glycidylmethacrylate) for Efficient Adsorption of Methylene Blue Enhanced by Aromatic–Aromatic Interactions

AbstractWater‐resistant porous solid foams expressing a high amount of benzene sulfonate moieties have been fabricated to enhance the adsorption of cationic aromatic pollutants from wastewaters by aromatic–aromatic interactions. Copolymers of sodium 4‐styrene sulfonate (NaSS) and glycidyl methacrylate (GMA) have been obtained and submitted to thermal treatment at 270 °C for 15 min. The influence of the solvent used in the copolymerization step on foamability and foam stability, when formed, has been studied. The use of water as cosolvent with N,N‐dimethyl formamide (DMF) inhibited foam formation. The use of DMF or DMF/dimethyl sulfoxide (DMSO) = 1:1 as solvents allowed the expansion of copolymers, but the resulting foams are unstable in water, forming hydrogels. However, using DMF/DMSO = 5:1 as solvent, stable water‐resistant foams showing NaSS molar fractions of 43, 57, and 68% are obtained, showing high maximum capacity of 244, 435 and 588 mg g−1 and outstanding pseudo‐second‐order kinetic constants of 1.78, 4.49 and 5.64 g mg−1 min−1 toward adsorption of methylene blue (MB), between 2 and 5 orders‐of‐magnitude higher than referenced adsorbents. This is due to the highly exposed benzene sulfonate active sites / adsorbent mass ratio that induces strong aromatic–aromatic interactions with the cationic aromatic dye.

Copper oxide nanocomposite particles supported on sodium alginate-g-polyallylamine based reduced graphene oxide: An efficient electrochemical sensor for sensitive detection of cadmium ions in water

A highly sensitive and selective electrochemical sensor, sodium alginate-g-polyallylamine/reducedgrapheneoxide/CuO nanocomposite particles ([email protected] NPs) has been synthesized for the detection of Cd2+ ions in the aqueous environment. The graft copolymer/reduced graphene oxide supported CuO nanocomposite particles are prepared through bioreduction of graphene oxide by a novel synthesized graft copolymer sodium alginate-g-PAAM (SAG-g-PAAM) to reduced graphene oxide (SAGPMRGO) followed by using it as both a reductant and a stabilizing agent to obtain [email protected] hybrid nanocomposite particles. The graft copolymer is prepared via free radical solution phase graft copolymerization technique. The graphene oxide (GO) is prepared by the oxidation of graphite using modified Hummer's method. The prepared nanocomposite particles are characterized by UV-VIS, FTIR and Raman spectroscopy, powder X-ray diffraction (PXRD), HRTEM-EDS, FESEM, XPS and DLS analysis with zeta potential measurement in colloidal suspension. The prepared graft copolymer is characterized by 1H and 13C NMR spectroscopy, PXRD and FESEM analysis and the SAMPGRGO is characterized by UV-VIS and Raman spectroscopy, PXRD and FESEM analysis. The CuO nanocomposite particles are spindle shaped with an average particle size ranges from 15.6 nm to 32.1 nm and are well polydispersed. Metal ion (Cd2+) sensing is carried out by cyclic voltammetry (CV) and chronoamperometry (CA) analysis under optimum conditions. The limit of detection (LOD) and limit of quantitation (LOQ) is found to be 1.27 nM and 4.24 nM respectively which is lower than some other reported works. The reproducibility and stability properties of the developed sensor are examined where the results are found to be satisfactory. The selective detection of Cd2+ ions in a river water sample is also evaluated with an excellent performance.

Formulation and In-Vitro Evaluation of Sustained Release Pilocarpine Ocuserts Using Modified Karaya Gum Extracted from Sterculia urens

Ocular inserts of Pilocarpine nitrate (PN) were prepared using modified karaya gum (MKG) alone as release retarding polymer and in combination with the copolymer sodium alginate. Modification of the karaya gum was done by treating it with the trisodium trimetaphosphate (STMP) by cross linking method and evaluated for its physicochemical properties. Films of the MKG were prepared by employing solvent casting method using varying concentrations (600mg, 500mg and 400mg) of MKG and the sandwiching technique was used for the loading of drug. Sodium alginate (SA) and PN blend were prepared by triturating their appropriate amounts. Six ocusert formulations (F1-F6) were prepared with different concentrations of the polymer i.e MKG and SA while the amount of PN was kept constant in formulations. Formulations F1-F3 contained the MKG alone in varying concentrations (600mg, 500mg and 400mg) and F4-F6 contained SA (0.5 mg) in addition to MKG. The surface pH of prepared ocuserts from the formulations (F1-F6) was in the range of 6.63 to 6.8. Thickness range of the ocuserts was from 0.21 to 0.32 mm. Dissolution profiles of prepared ocuserts were studied and drug release was found within the range of 69.2± 1.36 % (F4, minimum) to 90.5± 3.21% (F3, maximum). Overall results of the study concluded that ocuserts fabricated with MKG and SA at optimized concentrations have the potential to sustain the release of PN and therefore reducing dosing frequency and adverse effects.

Structure and dynamics of sodium alginate as elucidated by chemical shift anisotropy and site-specific spin-lattice relaxation time measurements.

The biocompatible, biodegradable, linear copolymer sodium alginate is fabricated from [Formula: see text] linked [Formula: see text]-D-mannuronic acid (M block) and [Formula: see text]-L-guluronic acid (G-block). It has wide applications in drug delivery, cell encapsulation, and commercial application in the textile, cosmetics, paper, food, biomedical, and pharmaceutical industries. The structure and dynamics of sodium alginate were here investigated by measuring chemical shift anisotropy (CSA) parameters, spin-lattice relaxation time, and molecular correlation time. The principal components of the CSA tensor were determined by two-dimensional phase-adjusted spinning sideband (2DPASS) cross-polarization magic angle spinning (CP-MAS) SSNMR. The alternating M and G blocks of both equatorial and axial links are associated with greater overall flexibility. The molecular correlation time of the carboxyl carbon of both G and M blocks is faster than for the anomeric carbon and pyranose carbon. This is further experimental evidence of the coexistence of two different dynamics within the polysaccharide chains of sodium alginate, which was previously established by 1H-13C dipolar profile analysis. The relaxation time of the para-crystalline region of sodium alginate is comparable with that of chitosan, but it is much shorter than that of cellulose and chitin. The order of the molecular correlation time of sodium alginate and chitosan is also the same. Hence, it can be concluded that sodium alginate exhibits greater flexibility than cellulose and chitin. These types of investigation into the local electronic configuration and nuclear spin dynamics at various carbon nuclei sites of the biopolymer at atomic-scale resolution will help in the design of biomimetic materials.

Recycling of waste PP and crumb rubber together by use of self-healing ionomer as process compatibilizer

Recycling of mixed waste, including plastic and rubber, by the blending process is one of the promising sustainable routes. In this paper, the processing of crumb rubber with waste thermoplastic polypropylene is reported. The poly(ethylene-co-methacrylic acid) copolymer sodium ion was introduced as a compatibilizer. The waste materials were processed by injection molding to a property improved value-added plastic–rubber recyclate. There was an improvement of tensile strength and modulus of about 60 and 85%, respectively, by addition of 7 wt.% of ionomer as compatibilizer. Enhanced thermal stability was also observed as compared to that of neat blend. The change in morphological characteristics that influence the end properties was analyzed by field emission scanning electron microscope and atomic force microscope. Evaluation of dispersion of different phases and their stress transfer tendency was studied for both tensile fractured and molded samples. The changes in thermo-mechanical properties are correlated to morphological characteristics, and the efficacy of the compatibilization process was estimated.

The role of carboxylic groups in heparin-mimicking polymer-functionalized surfaces for blood compatibility: Enhanced vascular cell selectivity

Blood compatibility is an eternal topic of biomedical materials. The effect of heparin-mimicking polymers (HMPs) on blood compatibility has been well studied, especially the synergistic effect of sugar unit and sulfonate/sulfate unit. However, carboxylic groups also play an important role in HMPs. In this work, copolymers of sodium 4-vinyl-benzenesulfonate (SS) and 2-methacrylamido glucopyranose (MAG) (poly(SS-co-MAG)) and poly(acrylate acid) (PAA) were self-assembled on Au surfaces with different feed ratios. When self-assembly of poly(SS-co-MAG) alone, the optimized feed ratio of SS and MAG for vascular cell selectivity was 1:1 (PS1M1); at this ratio the Au-PS1M1 surface showed the highest human umbilical vein endothelial cells (HUVECs) density and the lowest human umbilical vein smooth muscle cells (HUVSMCs) density. When self-assembly of PAA alone (surface designated as Au-PAA), the proliferation of both HUVECs and HUVSMCs was inhibited. Compared with either PS1M1 or PAA alone, the surfaces modified with both PAA and PS1M1 at the feed ratio of 1:1 (material designated as Au-PSM/PAA-2) showed enhanced promoting effect on HUVECs as well as enhanced inhibiting effect on HUVSMCs, indicating stronger vascular cell selectivity of carboxylic groups in the presence of sugar and sulfonate units.

Effect of superabsorbent polymer characteristics on rheology of ultra-high performance concrete

Abstract Changes of rheological properties in ultra-high performance concrete (UHPC) suspending mortar incorporated superabsorbent polymer (SAP) were investigated. The effect of chemical composition of two SAP types (S1, acrylamide/acrylic sodium copolymer and S2, acrylamide polymer) and the S1 SAP with mean particle sizes of 95.1 and 471.3 μm on water absorption was evaluated. The effect of these parameter for dry SAP used at content of 0–0.6%, by mass of cementitious materials, on the rheology of the UHPC mortar was evaluated. The S1 SAP was also employed at 0.4% content in a pre-absorbed state to investigate the effect of the preconditioning method on the rheological properties. Test results show that the rheology of UHPC made with SAP depend on the water absorption/desorption properties. The water desorption after reaching the maximum water absorption limit for the S1 SAP can led to a decrease or stagnation of yield stress between 15 and 30 min of age. The increase in particle size of the SAP was shown to delay this stage of decrease or stagnation. The variation in yield stress of UHPC mortar made with the S2 SAP over time increased from 1 to 4 times compared to the reference mixture given the longer time for water absorption. The addition of the S1 SAP reduced the plastic viscosity and thixotropy, regardless of the size, content, and preconditioning method. The use of dry S2 SAP increased plastic viscosity by approximately 10 Pa.s and the thixotropy. The preconditioning method of SAP had no significant influence on thixotropy.

Recycling of Quaternary Household Plastic Wastes by Utilizing Poly(Ethylene-co-Methacrylic acid) Copolymer Sodium Ion: Compatibility and Re-processability Assessments

The recycling of quaternary plastic wastes irrespective of their chemical nature into a value-added material has been investigated in this paper. Household plastic wastes like polyethylene terephthalate bottles, polyethylene bags, polyvinyl chloride sheets, and polypropylene decorative ribbons were recycled based on their polarity by utilizing poly (ethylene-co-methacrylic acid) copolymer sodium ion. The composition of the blend is varied by altering the level of loading of a two-phase compatibilizer. The composition with 7 wt% loading of compatibilizer showed improved properties than the neat blend. Tensile strength and elongation at break (%) improvement of 117% and 485%, respectively reflected in the composition containing 7 wt% of ionomer as a compatibilizer on comparing with 0 wt% of ionomer, making them ideal composition. The compatibilization and improved mechanical performances were supported by nanometric level phase morphological characteristics. The stability and thermal degradation of the compositions are discussed through thermal analysis. Comparative study on repeated processing up to three cycles and their compatibilization mechanism based on polarity has been reported here.

Sulfonated Copolymers as Heparin-Mimicking Stabilizer of Fibroblast Growth Factor: Size, Architecture, and Monomer Distribution Effects.

Fibroblast growth factors (FGF) are involved in a wide range of biological processes such as cell proliferation and differentiation. In living organisms, the binding of FGF to its receptors are mediated through electrostatic interactions between FGF and naturally occurring heparin. Despite its prevalent use in medicine, heparin carries notable limitations; namely, its extraction from natural sources (expensive, low yield and extensive purification), viral contamination, and batch-to-batch heterogeneity. In this work a range of synthetic homopolymers and copolymers of sodium 2-acrylamido-2-methylpropanesulfonate were evaluated as potential FGF stabilizers. This was studied by measuring the proliferation of BaF3-FR1c cells, as a model assay, and the results will be compared with the natural stabilization and activation of FGF by heparin. This study explores the structure-activity relationship of these polysulfonated polymers with a focus on the effect of molecular weight, comonomer type, charge dispersion, and polymer architecture on protein stabilization.

Novel spray dried pH-sensitive polyacrylamide-grafted-carboxymethylcellulose sodium copolymer microspheres for colon targeted delivery of an anti-cancer drug

Unique pH-sensitive spray dried microspheres were formulated employing hydrolyzed polyacrylamide-g-carboxymethylcellulose sodium (PAAm-g-NaCMC) co-polymer for colon targeted delivery of an anticancer drug, capecitabine. Synthesis of PAAm-g-NaCMC was carried out through free radical polymerization, which was supported with an inert atmosphere and then the alkaline hydrolysis was performed and subjected for characterization including FTIR spectroscopic analysis, 1H NMR spectroscopic analysis, elemental analysis, viscosity measurement, neutralization equivalent and thermo-gravimetric investigation. The swelling data suggested that the PAAm-g-NaCMC possesses significant pH-sensitive property. The microspheres were in the range of 1.00 to 7.34 μ and the drug entrapment efficiency ranged between 70.98 and 94.41%. In vitro drug release suggested the failure of microspheres formulated using native NaCMC which failed to impede drug release in stomach and small intestine, while those prepared with pH-sensitive PAAm-g-NaCMC copolymer and cross-linked with glutaraldehyde are suitable for colon targeting because they retarded release of drug in physiologic atmosphere of stomach and small intestine. Only 12.97% of drug was released from CMC10 formulation by the end of 5th h and rest of drug has been targeted to colonic region. A sudden increase in release of drug was observed in rat caecal contents media because of colonic bacterial action on PAAm-g-NaCMC copolymer.

Thermo-sensitive complex micelles from sodium alginate-graft-poly(N-isopropylacrylamide) for drug release

Polymer micelles with environmentally sensitive properties have potential applications in biomedicine. In this paper, thermo-sensitive complex micelles assembled from biocompatible graft copolymers sodium alginate-graft-poly(N-isopropylacrylamide) (SA-g-PNIPAM) and divalent metal ions were prepared for controlled drug release. The polymer micelles had core-corona structure, which was constituted by metal ions (Ba(2+), Zn(2+), Co(2+)) cross-linked sodium alginate as the core and thermo-sensitive PNIPAM chains as the corona. Formation of polymer micelles was determined by Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The polymer micelles were observed as regular spheres with good polydispersity and excellent performance on drug encapsulation and release ability. The cumulative release of 5-fluorouracil (5-FU) from micelles was controlled by pH, ionic strength or temperature of surroundings. The superior properties of sensitive polymer micelles induced by metal ions are expected to be utilized in controlled drug delivery systems.

Surface - Active and Complexforming Copolymers of Sodium 2-acrylamido-2-methylpropanesulfonate with Ethyleneglycol Vinyl Ether

<p>A new water-soluble polyelectrolyte - the copolymer of sodium 2-acrylamido-2-methylpropanesulfonate and ethylene glycol vinyl ether has been synthesized by free-radical copolymerization in aqueous medium. Synthesis of the linear structure water-soluble copolymer of sodium 2-acrylamido-2-methylpropanesulfonate (Na-AMPS) and ethylene glycol vinyl ether (EGVE) has been confirmed by IR spectroscopy method, potentiometric titration and viscometer. The concentration behavior of the reduced viscosity of copolymer solutions that is typical for polyelectrolytes has been revealed. The reactivity ratios for the copolymerization of the monomers estimated by the Mayo–Lewis method have indicated lower reactivity of ethylenglycol vinyl ether in comparison with sodium 2-acrylamido-2-methylpropanesulfonate. Also it was shown the decrease of reaction’s relative rate with an increase of molar fraction of EGVE in the initial mixture of monomers. Adsorption at the air-water solution interface was studied by measure of surface tension (σ) in order to determine the surface properties of new copolymers of ethyleneglycol vinyl ethers – sodium 2-acrylamido-2-methylpropanesulfonate. It was shown that copolymers of sodium 2-acrylamido-2-methylpropanesulfonate and ethylenglycol vinyl ether have higher surface activity compared to sodium 2-acrylamido-2-methylpropanesulfonate homopolymer. The isotherm of copolymer’s surface tension based on equilibrium value of σ was constructed together with the isotherm of surface tension water solution poly- Na-AMPS. Based on isotherms the surface activity on Rebinder (G<sub>Re</sub>) for poly- Na-AMPS and copolymer Na-AMPS-EGVE was determined. The values of polymer’s standard free energy of adsorption (Δ<sub>ads</sub>G<sup>0</sup><sub>298</sub>) were calculated in order to identify the causes and mechanism of change in surface activity and adsorption. Results show that the gain in standard free energy adsorption in the transition from homopolymer to copolymer Na-AMPS-EGVE is about 4 kJ/base-mole. Interpolymer reaction of the Na-AMS–EGVE copolymer with poly- <em>N,N</em>-dimethyl-<em>N,N</em>-diallylammonium chloride (PMAAC) has been studied. Higher surface activity of mixtures of copolymer and PMAAC than of individual polyelectrolytes was discovered. This effect testified to the formation of interpolymer complex of the Na-AMS–EGVE copolymer with polycations due to electrostatic interactions.</p>

Hydrogen bond cross-linked sulfonated poly(imino ether ether ketone) (PIEEK) for fuel cell membranes

A new diamine monomer, 3,3′-dihydroxydiphenylamine, is prepared by the palladium catalyzed C–N coupling reaction and the following reduction reaction of 3-bromoanisole and m-anisidine. A series of novel hydrogen bond cross-linked sulfonated poly(imino ether ether ketone) (SPIEEK) are obtained by the copolymerization of sodium 5,5′-carbonylbis(2-fluorobenzene sulfonate), 4,4′-difluorobenzophenone with 3,3′-dihydroxydiphenylamine. The structures of resulting polymers are characterized by means of FT-IR, 1H NMR spectroscopy, and elemental analysis; the results show an agreement with the proposed structure. The resulting SPIEEK membranes display much better resistance to swelling than these without imino groups due to the strong interchain interaction through imino and sulfonic acid groups. The SPIEEK-60 and SPIEEK-80 membrane show the proton conductivity of 0.118 and 0.154 S cm−1 at 80 °C which is higher than Nafion 117 (0.082 S cm−1 at 80 °C). Moreover, the SPIEEK membranes exhibit good mechanical properties and lower methanol permeability due to the hydrogen bondings between the polymer chains.

Preparation of gold nanoparticles by a novel biodegradable graft copolymer sodium alginate-g-poly (N,N-dimethylacrylamide-co-acrylic acid) with anti micro bacterial application

Abstract Sodium alginate-g-poly-(N,N-dimethylacrylamide-co-acrylic acid) was prepared in presence of potassium peroxydisulfate (K2S2O8) as the initiator by solution polymerization technique. The so prepare graft copolymer was characterized by different characterization techniques like determination of molecular weight by SEC, FTIR, 1H NMR and 13C NMR spectroscopy, XRD-studies. Biodegradation of the graft copolymer was analyzed by enzymatic cleavage. The graft copolymer was used to synthesize gold nanoparticles from chloroauric acid tetra hydrate (HAuCl4, 4H2O) without addition of any reducing agent. The gold nanoparticles were characterized by UV–VIS spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Analysis (EDAX). The effects of various synthetic parameters such as polymer and chloroauric acid (HAuCl4, 4H2O) concentration, pH, reaction time and temperature were studied for finding optimum condition. It was shown that the synthesized nanoparticles were rice shaped. One type of synthesized gold nanoparticles, under optimized condition was used for antimicrobial activity against both gram-negative and gram-positive bacteria by agar well diffusion method. The gold nanoparticles prepared under optimum condition exhibits excellent anti bacterial sensitivity to one gram negative bacteria Vibrio parahaemolyticus (ATCC-17802) and one gram positive bacteria Bacillus subtilis (ATCC-11774).

Hybrid vesicles co-assembled from anionic graft copolymer and metal ions for controlled drug release

Abstract In this paper, hybrid vesicles assembled from hydrophilic graft copolymer sodium alginate-g-poly(N-isopropylacrylamide) (ALG-g-PNIPAM) and multivalent metal ions (Ca2+ and Al3+) for controlled release of 5-Fluorouracil (5-FU) were studied. Transmission electron microscopy (TEM) showed that the vesicles had a well-defined hollow structure with a size of about 100 nm. The hydrophobic membrane was formed by the negatively charged sodium alginate cross-linked with metal ions, and the diffuse corona was constituted of swollen neutral polymer chains. The high stability of vesicles was the result of the nature of coordination complex bonds between anionic sodium alginate chains and metal ions. The lower critical solution temperature (LCST) of polymer vesicles was in the region of 37 °C. The drug loading efficiency of hybrid vesicles was high due to the large cavities of hollow structure and intermolecular attractions with drug. Changing temperature, pH or ionic strength, a sustained and controlled drug release was observed. The novel hybrid polymer vesicles are expected to be used in the field of intelligent drug delivery system.

Synthesis, characterization, and aqueous properties of new amphiphilic copolymer with fluorocarbon groups

A series of amphiphilic copolymers with fluorocarbon groups (Poly(AMPS-co-FS), PAMFS) were synthesized by the radical copolymerization of sodium 2-acryamido-2-methylpropanesulfonate (AMPS) and styrene derivatives with a fluorocarbon side chain (FS). The structures and molecular characteristics of PAMFS were confirmed by 1H-NMR, 19F-NMR, elemental analysis, and static light scattering. The aggregation behavior of the copolymer in aqueous solution was studied by surface tension, electrical conductivity, dynamic laser light scattering, transmission electron microscopy, and fluorescence measurements at different conditions. The results indicated that the surface activity of PAMFS is dependent on the content of fluorocarbon groups in the copolymer structure. The surface tension (γ cmc) and critical micelle concentration of PAMFS decrease with the increase of sodium chloride concentration. The copolymers formed micelle-like aggregates and the fluorocarbon groups exhibited a strong tendency for intermolecular association.

Copolymerization of sodium 2-acrylamido-2-methylpropane sulfonate with acrylamide and acrylonitrile in water: an effect of conditions on the compositional heterogeneity

The copolymerization of sodium-2-acrylamido-2-methylpropane sulfonate with acrylonitrile and acrylamide in water has been studied at different concentrations of monomers, the initiator and the external electrolyte (NaCl). It was shown that an increase in the total concentration of the monomers leads to enriching the copolymers with units of the ionic monomer. A decrease in the initiator concentration causes the increase of the nitrile content in the product. Using of reactivity ratios r1 and r2 was shown to be invalid for this system as it does not allow one to appropriately predict the copolymer composition or its microstructure. The observed effects of significant dependence of copolymers composition on these factors have been explained by the influence of prepolymerization processes of formation of monomer assemblies and aggregates of monomers with growing macroradicals.

Preparation of polyaniline coated polystyrene‐poly(styrene‐co‐sodium 4‐styrenesulfonate) microparticles and the further fabrication of hollow polyaniline microspheres

AbstractIn this article, the microparticles of polystyrene‐poly(styrene‐co‐sodium 4‐styrenesulfonate) (PS‐PSS) coated by polyaniline (PANI) were prepared and hollow PANI microspheres were further obtained by dissolving the core. First, surface‐sulfonated monodispersed PS was prepared by copolymerization of sodium 4‐styrenesulfonate (SSS) and styrene with dispersion polymerization method. Then aniline was polymerized on the surface of the surface‐sulfonated PS (PS‐PSS) by chemical oxidative polymerization. After purification, we prepared core‐shell (PS‐PSS)/PANI particles. Hollow PANI microspheres were prepared by dissolving the plastic PS core of the (PS‐PSS)/PANI particles in chloroform. The growth process of PANI on the surface of PS‐PSS particles was investigated and the hollow PANI microspheres were characterized. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Salt and Heat Induced Aggregation of Diblock Copolymers of Sodium 2-(acrylamido)-2-methylpropanesulfonate and N-Isopropylacrylamide in Aqueous Solutions

Heat and salt induced aggregation of three well-defined double hydrophilic block copolymers (DHBCs) of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS) and N-isopropylacrylamide (NIPAM) with constant chain length of the PAMPS block (with number-average degree of polymerization, DP n = 61) and varying chain length of the PNIPAM block with DP n = 11, 23, and 34 synthesized via reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization was investigated by turbidity, dynamic light scattering (DLS) and 1H NMR measurements. In the presence of salt or with an increase in temperature, the diblock copolymers form micelles with a PNIPAM core and PAMPS corona. The heat and salt induced aggregation in dilute aqueous solutions dependant on the molecular characteristics of the DHBC (DP n of the PNIPAM block) was observed. The DHBC becomes amphiphilic as the PNIPAM block loses hydrophilicity at higher temperature above its lower critical solution temperature (LCST). Furthermore, the presence of salt induces salting out effect of the uncharged PNIPAM block. The diblock copolymer thus forms nanosized aggregates at a high temperature or in the presence of salt. These aggregates may be multiple aggregates due to inter-micellar aggregation of the spherical core-corona micelles.

Copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in water-dimethyl sulfoxide solutions

The solvent effect on the kinetic features of the synthesis and molecular characteristics of the copolymers in homogeneous radical copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in water and water-dimethyl sulfoxide mixtures (75: 25, 50: 50, 25: 75) at pH 9 and 60°C in the presence of potassium persulfate was studied