Controlled release of 5-aminosalicylic acid from a new pH responsive polymer derived from tamarind seed polysaccharide,acrylic acid,and polyamidoamine

A new pH-responsive polymer (TKP–AA–PAA) was synthesized from the combination of tamarind kernel powder (TKP), acrylic acid (AA), and polyamidoamine (PAA) which was utilized for controlled release of 5-aminosalicylic acid (5-ASA) in buffer medium. The network structure of TKP–AA–PAA was obtained by irradiating the mixture of TKP, AA, and PAA in different proportion in presence of 2,2-dimethoxy-2-phenyl acetophenone as a photoinitiator. The dynamic and equilibrium swelling properties of the polymeric materials were studied as a function of pH and time in different buffer solutions similar to that of gastric and intestinal fluids. The controlled release kinetics of 5-ASA in simulated body fluid showed a Fickian diffusion behavior.     

Morphology of Organic–Inorganic Hybrid Composites in Thin Films as Multichip Packaging Material

Silica–polyimide hybrid composites were prepared via a sol–gel process and thermal imidization. Two different types of soluble precursors, poly(amic acid) (PAA) and poly(amic diethyl ester) (ES), chemically convertible to poly(p-phenylene biphenyltetracarboximide), were used as organic polymer matrix component, and tetraethoxysilane (TEOS), convertible to silica, as the inorganic component. The structure of composites prepared as thin films was investigated by means of small-angle X-ray scattering, scanning electron microscopy and atomic force microscopy. Nanometre-scale composites were successfully obtained for ≤30wt% TEOS-loaded mixtures with ES and PAA. It was considered from the microstructural investigation that the composite films based on ES were not significantly affected by the inorganic particles generated, maintaining the structure of the homopolyimide, while those based on PAA did not preserve the structure due to the nanoparticles grown in situ during the sol–gel process. © 1997 SCI.     

The chemistry involved in the loading of silver(I) into poly(amic acid) via ion exchange: A metal-ion-induced crosslinking behavior

Metal-ion-induced crosslinking of poly(amic acid) (PAA) was observed in the incorporation of silver ions into PAA through ion exchange. Studies on the interaction of silver ions with 3,3′,4,4′-benzophenonetetracarboxylic acid/4,4′-oxidianiline (BTDA/ODA)-based PAA suggest that the ion exchange reactions between poly(amic acid) and silver ions are not so simple as what we generally believed. It involves not only the formation of silver carboxylate but also the generation of diversified silver chemical entities arising from the strong chemical bonding of metal ions with the functional groups, such as carbonyl groups and amide groups, in the polymer chain, which are suggested to be responsible for the crosslinking behavior. Moreover, silver ions loaded into the film are readily self-reduced and provides us a convenient route to disperse very small metal nanoparticles into the polymeric matrix. Meanwhile, strong accelerating effect of silver ions was observed on the hydrolysis of PAA molecules and the characterization results indicate that about 14-16 wt% precursors were dissolved during the ion exchange in the aqueous silver ion solutions. Fortunately, it is found that the metal-ion-induced crosslinking structure formed in the silver-doped film has helped to prevent the damaging effect of silver ions and the essential structural features of PAA were retained in the remaining polymer matrix.     

Triple percolation behavior and positive temperature coefficient effect of conductive polymer composites with especial interface morphology

Selective localization of carbon black (CB) at the interface of polymer blends was achieved by the method that poly(styrene-co-maleic anhydride) (SMA) was first reacted with CB, and then blended with nylon6/polystyrene (PA6/PS). In the PA6/PS blends, CB was localized in PA6 phase and typical double percolation was exhibited. In the PA6/PS/(SMA–CB) blends, TEM results showed that CB particles were induced by SMA to localize at the interface, resulting in the especial interface morphology fabricated by SMA and CB. The especial interface morphology of PA6/PS/(SMA–CB) caused distinct triple percolation behavior and very low percolation threshold. The positive temperature coefficient (PTC) intensity of PA6/PS/(SMA–CB) composites was stronger than that of PA6/PS/CB and the negative temperature coefficient (NTC) effect was eliminated. The elimination of NTC effect was arisen from the especial interface morphology. A stronger PTC intensity was attributed to the low percolation threshold and the morphology.     

Inhomogeneity of hydrolytic polyamide 6 with respect to the average molecular mass

The point of view was advanced that in spinning fibres from polymer melts, the molecular inhomogeneity of the melts is not due to the polydispersity of the polymer but to important differences in the average molecular mass of the individual granules. Using the example of three industrial samples of hydrolytic PA 6, it was shown that the standard deviation of the average molecular mass of the polymer with respect to the individual granules from its mean statistical values is at the level of 10–11% for a practically significant (for up to several percent of granules) deviation of 30–50%. The use of samples of PA 6 with the mass provided by GOST 18245–72, OST 6-06-S9-76, and GOST 11034-82 in determining the viscosity a solution of the polymer in H₂SO₄ allows correctly estimating its average molecular mass but makes it impossible to obtain reliable information relative to the real degree of inhomogeneity of the granulate based on this index. Translated from Khimicheskie Volokna, No. 5, pp. 26–28, September–October, 2008.     

The variation of cholesteric order during polymerization of the solvent in liquid crystalline solutions

Summary Ethyl-cyanoethyl cellulose [(E-CE)C]/acrylic acid (AA) formed a cholesteric liquid crystalline solution with vivid colors when the concentration is 42–52 wt%. (E-CE)C/polyacrylic acid (PAA) composites with cholesteric structure were prepared by polymerization of the AA in the (E-CE)C/AA liquid crystalline solutions. The layers of ordered polymer chains in the cholesteric phase were inclined during polymerization and the degree of the inclination depended on the polymerization temperature and the concentration of the solution before polymerization. Key words: Cholesteric structure, polymerization, and selective reflection. Received: 19 January 2000/Revised version: 13 March 2000/Accepted: 29 March 2000     

Fibre materials based on ultrahigh-molecular-weight polyethylene and montmorillonite nanoparticles

The effect of the thermodynamic quality of the solvent on the properties of polymer solutions was determined. Thermal annealing affects formation of the structure and the mechanical properties of UHMPE. Fourier transform IR spectroscopy revealed the effect of the filler on the structure of the polymer matrix. The morphology of filled UHMPE fibres was characterized by optical microscopy; the fibres have a longitudinally oriented structure and the filler aggregates in particles up to 50 μm in size, which does not allow classifying the materials obtained as nanocomposites. Translated from Khimicheskie Volokna, No. 3, pp. 4–8, May–June, 2008.     

Electroactive behavior assessment of poly(acrylic acid)‐graphene oxide composite hydrogel in the detection of cadmium

Super absorbent polymers of acrylic acid‐graphene oxide (PAA‐GO) were synthesized with different percentage of chemical neutralization (0, 10, and 20%) of the acrylic acid monomer before its polymerization. The influence of their swelling and adsorption/desorption capacity of cadmium ions in aqueous solutions were studied and revealed that the GO enables greater mechanical stability in the materials. The PAA hydrogels, with the same degrees of neutralization, were also prepared without GO to compare with the composites. Additionally, carbon paste electrodes (CPE) modified with the composites PAA‐GO were used to asses and compare their adsorption properties with cadmium(II). The anodic stripping voltammetry (ASV) peak, in the differential pulse voltammetry mode, for cadmium oxidation was found to be influenced by the presence of GO into the polymer, and also by their percentage of neutralization. The accumulation of cadmium(II) on the surface of the modified CPEs was performed under open‐circuit conditions taking an account the preconcentration time of the metal cation. The presence of GO enhances the electrical signal of the electrodes in short times of immersion in cadmium(II) solutions. This property contributed to get linear responses of the CPEs modified with the composites, which were influenced by their degrees of neutralization. The PAA‐GO 10N electrode with 10% of neutralization combined the influence of GO and the degree of neutralization in the same matrix, and also showed good performance in terms of its mechanical stability, it was chosen for preliminary studies on the selectivity of the electrode toward Zn(II) and Cu(II). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40846.     

Viscosity properties of aqueous solutions of carboxymethylcellulose and hydroxyethylcellulose blends

The possibility of using hydroxyethylcellulose (HOEC) as a modifier polymer for regulating crosslinking processes in Na-carboxymethylcellulose (CMC) solutions was established. The effect of differences in the conformation of the macromolecules of miscible polymers not only on the intensity of intermolecular interaction but also on structuring of the solution was revealed. The decrease in the total concentration of components of the solution and the molecular mass of one of the miscible polymers causes the appearance of individuality of the macromolecules, confirmed by the deviation of the thermodynamic characteristics of viscous flow from additivity. __________ Translated from Khimicheskie Volokna, No. 1, pp. 11–14, January–February, 2007.     

Improving properties of superabsorbent composite induced by using alkaline protease hydrolyzed‐sericin (APh‐sericin)

A series of superabsorbent polymer composites based on sericin hydrolyzed with alkaline protease (AP) were prepared by grafting with acrylic acid (AA) and acrylamide (AM). The properties of the superabsorbent polymers (SAP) by using hydrolyzed sericin with different amount of alkaline protease (nAPh‐sericin) were compared. It was found that the polymer prepared from 5APh‐sericin (the mass ratio of AP to sericin was 5.0 mg g⁻¹) showed the highest graft percentage and water absorbency, this phenomenon may be attributed to the change of molecular weight of resulting sericin molecules. The molecular structure of the grafted polymers was proved by thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) measurements. Comparing with PAA‐AM (poly AA‐co‐AM) and 0APh‐sericin/PAA‐AM polymer, 5APh‐sericin/PAA‐AM polymer had the most excellent water retention capacity and enzyme degradability. The morphological features of the polymers with different drying methods were evidenced by SEM images. The water absorbencies of 5APh‐sericin/PAA‐AM polymer prepared with freeze‐drying were 896 g g⁻¹ in deionized water, 424 g g⁻¹ in tap water, and 83 g g⁻¹ in 0.9 wt% aqueous NaCl solution. POLYM. COMPOS., 35:509–515, 2014. © 2013 Society of Plastics Engineers     

The modifying effect of weak aqueous solutions of ammonia on poly(ethylene terephthalate) materials

The effect of water and aqueous solutions of ammonia of 0.02–0.04 M concentration on poly(ethylene terephthalate) and fleecy knit fabric was comparatively investigated at high temperatures. It was found that migration of oligomers to the surface of the polymer, partial hydrolysis of cyclic oligomers to the linear form, and total hydrolysis to TPA are possible under the effect of water, but water affects the knit much less than the film. The presence of ammonia intensifies the processes that can take place with oligomers of PET at high temperatures to a significant degree. The concentration of ammonia in the system determines which of these processes will predominate. It was found that a 0.015–0.03 M concentration of ammonia is optimum for refining polyester fibre materials. __________ Translated from Khimicheskie Volokna, No. 6, pp. 15–18, November–December, 2006.     

Properties of composites containing biologically active substances and the polymeric materials prepared from them

The effect of the structure of polysaccharides containing ionogenic groups on the properties of proteolytic enzymes included in the structure of polyelectrolyte complexes was investigated. A correlation was established between the composition of the polymer composites containing the proteolytic enzyme, the antimicrobial, and the modifying additives and the properties of the fibre and film materials prepared from them. Moscow State Textile Academy. Translated fromKhimicheskie Volokna, No. 4, pp. 32–38, July–August, 1999.     

Development of methods of manufacturing nonwoven sorbing materials

Impregnation composites and the conditions for fabricating them to make filled nonwoven materials with elevated physicomechanical properties were developed. The use of impregnation composites with a filler undergoing vibrational treatment in optimum conditions allows obtaining nonwovens with the ability to sorb heavy metal ions from aqueous solutions of surfactants and to selectively sorb microorganisms. __________ Translated from Khimicheskie Volokna, No. 3, pp. 3–5, May–June, 2006.     

Synthesis,characterization and swelling behaviors of hydroxyethyl cellulose‐g‐poly(acrylic acid)/attapulgite superabsorbent composite

In this work, a series of novel hydroxyethyl cellulose‐ g‐poly(acrylic acid)/attapulgite (HEC‐g‐PAA/APT) superabsorbent composites were prepared through the graft polymerization of hydroxyethyl cellulose (HEC), partially neutralized acrylic acid (AA), and attapulgite (APT) in aqueous solution, and the composites were characterized by means of Fourier‐transform spectroscopy, scanning electron microscopy, and transmission electronmicroscopy. The effects of polymerization variables including concentrations of the initiator and crosslinker and APT content on water absorbency were studied, and the swelling properties in various pH solutions as well as the swelling kinetics in various saline solutions were also systematically evaluated. Results showed that the introduction of 5 wt% APT into HEC‐g‐PAA polymeric network could improve both water absorbency and water absorption rate of the superabsorbent composites. In addition, the superabsorbent composites retained high water absorbency over a wide pH range of 4–10, and the swelling kinetics of the superabsorbent composites in CaCl₂ and FeCl₃ solutions exhibited a remarkable overshooting phenomenon. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Nanosized colloidal particles from thermosensitive poly(methoxydiethyleneglycol methacrylate)s in aqueous media

The formation of well-defined colloidal particles (mesoglobules) from the thermosensitive polymer poly(methoxydiethyleneglycol methacrylate) was observed in dilute aqueous solutions (0.5–1.0 g/L) by turbidimetry and dynamic light scattering (DLS). DLS measurements were performed at 70 °C and showed a strong influence of polymer molecular weight: the hydrodynamic diameters of the mesoglobules increased from ca. 160 to 330 nm with a relatively small, i.e., from 6,400 to 14,000, increase in molecular weight. The addition of sodium dodecyl sulfate (SDS) at surfactant/polymer ratios (s/p, g/g) ranging from 0.3 to 0.5 practically inhibited the clouding of the solutions as the initial transmittance decreased by only 10–30%. Furthermore, a dramatic shift of the original cloud point values taken as a 10% decrease in transmittance, by approximately 20–60 °C was registered upon the surfactant addition. The presence of SDS resulted in size reduction by 52–90% as indicated by DLS.     

Nanoparticles of Block Ionomer Complexes from Double Hydrophilic Poly(acrylic acid)-<Emphasis Type="Italic">b</Emphasis>-poly(ethylene oxide)-<Emphasis Type="Italic">b</Emphasis>-poly(acrylic acid) Triblock Copolymer and Oppositely Charged Surfactant

The novel water-dispersible nanoparticles from the double hydrophilic poly(acrylic acid)-b-poly(ethylene oxide)-b-poly(acrylic acid) (PAA-b-PEO-b-PAA) triblock copolymer and oppositely charged surfactant dodecyltrimethyl ammonium bromide (DTAB) were prepared by mixing the individual aqueous solutions. The structure of the nanoparticles was investigated as a function of the degree of neutralization (DN) by turbidimetry, dynamic light scattering (DSL), ζ-potential measurement, and atomic force microscope (AFM). The neutralization of the anionic PAA blocks with cationic DTAB accompanied with the hydrophobic interaction of alkyl tails of DTAB led to formation of core–shell nanoparticles with the core of the DTAB neutralized PAA blocks and the shell of the looped PEO blocks. The water-dispersible nanoparticles with negative ζ-potential were obtained over the DN range from 0.4 to 2.0 and their sizes depended on the DN. The looped PEO blocks hindered the further neutralization of the PAA blocks with cationic DTAB, resulting in existence of some negative charged PAA-b-PEO-b-PAA backbones even when DN > 1.0. The spherical and ellipsoidal nature of these nanoparticles was observed with AFM.     

Fabrication of modified fibre materials containing biologically active substances

The effect of the composition of a polymer composite used for treating unmodified textile material and the structure of the fibre matrix on the properties of the material obtained, which contains the proteolytic enzyme protease C and low-molecular-weight antimicrobial substances, was investigated. The factors that affect the biological activity and stability of biologically active fibre materials and the kinetics of separation of biologically active substance from them were established. The composition of the polymer composites which makes it possible to obtain fibre materials with long-lasting complex biological activity resistant to sterilization with γ-irradiation was determined. Translated from Khimicheskie Volokna, No. 6, pp. 15–21, November–December, 1997.     

Convective mass transfer in the system poly-m-phenylene isophthalamide solution—precipitator

The conditions of the appearance of convective currents in solutions of PmPIPA on contact with different precipitators were investigated. The dependence of the structure and properties of fibres, flat, and fibre membranes in fibre-film polymer binders on the development of convective currents in solutions of a polymer was demonstrated. Translated from Khimicheskie Volokna, No. 3, pp. 19–21, May–June, 1998.     

Synthesis and characterization of C60‐based composites of amphiphilic N‐vinylpyrrolidone/triethylene glycol dimethacrylate copolymers

It was found that under mixing of aqueous solutions of copolymers and toluene solutions of C₆₀ two types of polymer composites can be produced with different matrix structure, the fullerene content and an aggregation degree. The dimethacrylate enriched macromolecules migrate to toluene and the VP units enriched copolymer chains remain in water to form copolymer micelles and their aggregates in these media that solubilize and encapsulate the fullerene. The structure and properties of obtained polymer composites were studied by GPC with dual detection (RI and MALLS), FT‐IR, WAXS and SAXS methods. It is shown that in a composite based on N‐vinylpyrrolidone copolymer isolated from toluene the fullerene form larger particles, compare to that isolated from water. According to SAXS, the fullerene particles in a solid copolymer are organized in spherical objects with fine coil‐like structure. The stability of the composites in water, ethanol, and chloroform was shown to depend on the original polymer matrix structure and on copolymer/fullerene ratio. POLYM. COMPOS., 35:1362–1371, 2014. © 2013 Society of Plastics Engineers     

Microwave-induced shape-memory poly(vinyl alcohol)/poly(acrylic acid) interpenetrating polymer networks chemically linked to SiC nanoparticles

Microwave (MW)-induced shape-memory poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) interpenetrating polymer networks (SMP-IPNs) were prepared through in situ polymerization. Silicon carbide (SiC) nanoparticles were modified by 3-(methacryloyloxy) propyltrimethoxysilane (KH570). 3-(Methacryloyloxy) propyltrimethoxysilane was covalently bonded on the surface of SiC through the reaction of silanol and the methoxy groups. The polymerization of acrylic acid (AA) using N,N′-methylenebis (2-propenamide) (MBA) as cross-linker in PVA solution was initiated through the double bonds of KH-570 grafted on SiC, leading to a PAA polymer network cross-linked with MBA. The PVA molecular chains run through the PAA cross-linking network and form an IPN structure. Therefore, SiC as a strong MW absorbing material could be chemically cross-linked into polymer matrix. The effect of composition on the properties of SMP-IPN was studied using dynamic mechanical analysis, dielectric properties and shape memory effect (SME) test. The results showed that the introduction of SiC in IPNs not only provided samples with excellent MW-induced shape memory effect (SME), but also caused a higher equilibrium temperature under MW irradiation. Moreover, both SiC content and applied MW power affected the shape recovery properties of PVA/PAA interpenetrating composites. MW-induced SMPs offered great advantages such as fast recovery, high recovery rate, and remote actuation. This study provides the potential applications of the fast and environmentally friendly SMPs used as MW-responsive sensors, implantable devices, etc.