Effect of the nature and degree of crosslinking on the Rose Bengal uptake by DVB‐, NNMBA‐, HDODA‐, and TTEGDA‐crosslinked aminopolyacrylamides

Polyacrylamides with 2–20 mol % divinyl benzene (DVB), N,N′‐methylene‐bisacrylamide (NNMBA), 1,6‐hexanediol diacrylate (HDODA), and tetraethyleneglycol diacrylate (TTEGDA) crosslinking and without crosslinking were prepared by free radical solution polymerization. Amino functions were incorporated into these polymers by transamidation with excess ethylenediamine. The dye uptake of nonprotonated and protonated aminopolyacrylamides was followed by batch equilibration method towards Rose Bengal (RB), Methyl Orange (MO), Methyl Red (MR), and Methylene Blue (MB). RB uptake by the polyacrylamide‐supported systems is higher than other dyes. Generally the dye uptake by the protonated systems is higher than the nonprotonated systems. To optimize the conditions of dye uptake, the effect of the concentration of RB solutions, temperature, and pH were followed. Kinetic studies showed that the uptake of RB by both nonprotonated and protonated crosslinked aminopolyacrylamides is a phase boundary process followed by three‐dimensional diffusion. The extent of RB uptake by the various systems depends on the nature and degree of crosslinking, and the relative rigidity/flexibility ofthe polyacrylamide support. Thus, the dye uptake followed the order: linear > NNMBA‐ > DVB‐ > TTEGDA‐ > HDODA‐crosslinked system. The dye uptake followed the same trend as the variation of amino capacity with degree of crosslinking in the respective crosslinked system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Regioselective Synthesis of Phenols and Halophenols from Arylboronic Acids Using Solid Poly(N‐vinylpyrrolidone)/ Hydrogen Peroxide and Poly(4‐vinylpyridine)/Hydrogen Peroxide Complexes

Solid hydrogen peroxide complexes based on poly(N‐vinylpyrrolidone) and poly(4‐vinylpyridine) were prepared and used as solid hydroxylating reagents. These solid hydrogen peroxide equivalents are found to be much safer, convenient and efficient reagent systems for the ipso‐hydroxylation of arylboronic acids to the corresponding phenols in high yields at a faster rate. The versatility of the reagents has been further expanded for the one‐pot synthesis of halophenols. Density functional theory calculations were carried out on hydrogen peroxide complexes of N‐ethylpyrrolidone and 4‐ethylpyridine as models to get a better understanding of structure and behavior of hydrogen peroxide complexes of the polymers poly(N‐vinylpyrrolidone) and poly(4‐vinylpyridine) compared to aqueous hydrogen peroxide.     

Apparent activation energy of degradation of poly[acrylonitrile‐co‐(N‐vinylpyrrolidone)]

Differential scanning calorimetry results of the degradation of poly[acrylonitrile‐co‐(N‐vinylpyrrolidone)] in air are presented. The apparent activation energy of degradation was calculated using Kissinger's method. The effect of copolymerization conditions on the apparent activation energy was studied. Increasing the dimethylformamide concentration in the solvent mixture led to a rapid increase in the degradation apparent activation energy. The apparent activation energy decreased rapidly with increase in the comononer N‐vinylpyrrolidone concentration, and this change becomes less prominent as the weight ratio of N‐vinylpyrrolidone/acrylonitrile rises above 5/95. The apparent activation energy also increases with increasing copolymerization temperature. Copyright © 2004 Society of Chemical Industry     

Antibacterial activity and cytotoxicity of hydrogel–nanosilver composites based on copolymers from 2‐acrylamido‐2‐methylpropanesulfonate sodium

In this research, we contributed to the search for potential hydrogel–silver dressings by generating hydrogel–silver nanoparticles (AgNPs) composites prepared by the dipping of the crosslinked hydrogel poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) (1:1) and poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) (1:1) into an aqueous suspension of citrate‐stabilized AgNPs. The composites obtained were evaluated by an antibacterial activity assay on Staphylococcus aureus and Escherichia coli and subjected to an in vitro cytotoxicity assay for human fibroblasts. The composite formed from the hydrogel poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) with 3 mol % N,N‐methylene bisacrylamide showed the highest antibacterial activity and the least cytotoxicity among the composites tested; this makes it an excellent alternative as a potential dressing for the treatment of deep and exudative wounds. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39644.     

Strontium(II) ion uptake on poly(N‐vinyl imidazole)‐based hydrogels

In this article, we report on the extraction of Sr(II) ions from aqueous solution with a series of poly(N‐vinyl imidazole)‐based hydrogels. The hydrogels were synthesized by the crosslinking of N‐vinyl imidazole with four different crosslinkers with γ rays as initiators. The well‐characterized hydrogels were used as Sr(II) sorbents. Sr(II) uptake was determined with a colorimetric method with Rose Bengal anionic dye. Scanning electron microscopy–energy‐dispersive spectroscopy analysis of the Sr(II)‐loaded polymers was recorded to ascertain the uptake of Sr(II) ions. The experimental adsorption values were analyzed with the Freundlich and Temkin equations, and the kinetics of adsorption were investigated with a pseudo‐second‐order sorption kinetic model. The results show that the equilibrium data fit well in the Freundlich isotherm and followed a pseudo‐second‐order kinetic model. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Forgotten monomers: access to α‐modified N‐vinylpyrrolidone polymers via C‐alkylation

Alkylation of N‐vinylpyrrolidone using lithium diisopropylamide and bis(2‐bromoethyl) ether was carried out to obtain 3‐(2‐(2‐bromoethoxy)ethyl)‐1‐vinyl‐2‐pyrrolidone ( 2 ). The derivative 2 represents a versatile starting molecule for further modification via nucleophilic displacement yielding, for example, the bicyclic 2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one ( 4 ) or the ammonium salt 3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone ( 10 ). Via free radical polymerization of 4 and 10 , the corresponding homopolymers were obtained. Copolymerization of 4 and 10 with N,N′‐diethylacrylamide yielded water‐soluble materials. The thermosensitive solubility of copolymers poly[(2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one)‐co‐(N,N′‐diethylacrylamide)] and poly[(3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone)‐co‐(N‐vinylpyrrolidone)] in water was investigated. © 2015 Society of Chemical Industry     

Self‐assembled amphiphilic poly‐N‐vinylpyrrolidone nanoparticles as carriers for hydrophobic drugs: Stability aspects

Nanoparticles can experience numerous impacts during storage or after intravenous administration resulting in disassembly and/or drug leakage and affecting their efficiency as drug delivery systems. In this study, this crucial issue was addressed by investigating the stability of amphiphilic poly‐N‐vinylpyrrolidone derivative nanocarriers in blood serum, against destabilizing agents and during long‐term storage. All amphiphilic poly‐N‐vinylpyrrolidone derivative nanoparticles prepared in this study were found to possess sizes less than 150 nm, narrow size distribution, spherical morphology, and a slightly negative surface charge. These nanoparticles could efficiently entrap hydrophobic substances (pyrene and curcumin) while retaining excellent compatibility with red blood cells. Moreover, our studies demonstrate the stability of the nanoparticles during long‐term storage and upon dilution with body liquids enhancing their potential as stable in vivo carriers, which is critically important for intravenous drug delivery applications. All properties were found to strongly depend on the ratio between the hydrophobic and the hydrophilic moiety of the polymers under study. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45637.     

Synthesis and characterization of new soluble poly(ester‐imide)s containing noncoplanar 2,2′‐dimethyl‐4,4′‐biphenylene unit

A new diimide–diacid chloride (3) containing a noncoplanar 2,2′‐dimethyl‐4,4′‐biphenylene unit was synthesized by treating 2,2′‐dimethyl‐4,4′‐diamino‐biphenylene with trimellitic anhydride followed by refluxing with thionyl chloride. Various new poly(ester‐imide)s were prepared from 3 with different bisphenols by solution polycondensation in nitrobenzene using pyridine as hydrogen chloride quencher at 170°C. Inherent viscosities of the poly(ester‐imide)s were found to range between 0.31 and 0.35 dL g^?1. All of the poly(ester‐imide)s, except the one containing pendent adamantyl group 5e, exhibited excellent solubility in the following solvents: N,N‐dimethylformamide, tetrahydrofuran, tetrachloroethane, dimethyl sulfoxide, N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidinone, m‐cresol, o‐chlorophenol, and chloroform. The polymers showed glass‐transition temperatures between 166 and 226°C. The 10% weight loss temperatures of the poly(ester‐imide)s, measured by TGA, were found to be in the range between 415 and 456°C in nitrogen. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2486–2493, 2004     

Synthesis,characterization, and blood compatibility of copolymers of polyamidoamines and n‐vinylpyrrolidone

Two new polyamidoamines derived from piperazine (Pip)/cyclohexylamine (CHA) and N,N′‐methylene bisacrylamide (MBA) were synthesized and subsequently copolymerized with N‐vinylpyrrolidone (NVP) under suitable reaction conditions to yield the respective copolymers (Pip–MBA–NVP and CHA–MBA–NVP). The synthesized materials were characterized by spectroscopic techniques. The material surface characteristics were checked by contact angle measurement, and the data established the relative hydrophilic characteristics of the synthesized copolymers with respect to the control poly(N‐vinylpyrrolidone). A thrombus‐formation study indicated less (<1.2 mg) clot formation on the heparinized material surfaces within a 30‐min contact time with the acid citrate dextrose human blood. The percentage of hemolysis of the blood by the materials was also less than 5%. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4068–4074, 2003     

Biodegradable amphiphiles of grafted poly(lactide) onto 2‐hydroxyethyl methacrylate‐co‐N‐vinylpyrrolidone copolymers as drug carriers

This article describes the synthesis and characterization of 2‐hydroxylethyl methacrylate‐co‐N‐vinylpyrrolidone copolymers, (HEMA‐co‐NVP), via free radical polymerization followed by grafting of poly(lactide) onto (HEMA‐co‐NVP) copolymers, via ring opening polymerization using tin octoate as a catalyst. The copolymers and the grafted copolymers (i.e., amphiphiles) were subjected to sustained release studies using salicylic acid, as a model drug. Characterization of the formed copolymers was performed using ¹H‐NMR, ¹³C‐NMR, FTIR, TGA, DSC, and SEM techniques. Derivative of TGA thermogram was used to determine %hydrophilicity and %hydrophobicity in the grafted and ungrafted copolymers. The SEM morphology revealed porous layers with crispy structure that were most likely due to the presence of poly(lactide) chains. At lower content of poly(lactide) moiety, grafted copolymers showed non‐Fickian diffusion release rate, whereas Fickian diffusion release rate at higher content of poly(lactide) was observed. The increase of poly(lactide) content (i.e., larger %hydrophobicity) in the copolymer increased the drug‐sustainability, due to the consistent but porous amphiphilic degradable structures that allow controllable release of drug in time interval. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Adsorption behavior of poly(N,N‐dimethylacrylamide‐co‐na 2‐acrylamido‐2‐methylpropanesulfonate) on sand surface

The adsorption behavior of poly(N,N‐dimethylacrylamide‐co‐Na 2‐acrylamido‐2‐methylpropanesulfonate), an enhanced oil recovery polymer, was studied. Adsorption isotherms show that adsorption on bentonite is very high followed by that on limestone that, in turn, is much higher than that on sand surface following the order: bentonite ? limestone > sand. On the addition of NaCl, adsorption on sand surface decreased to a minimum value and then increased. Adsorption increased with decreasing pH and also decreasing the content of Na 2‐acrylamido‐2‐methylpropanesulfonate in the copolymer. The amount of the copolymer adsorbed on the sand surface is comparable to that of partially hydrolyzed polyacrylamide but much less than that of poly(acrylamide‐co‐vinylpyrrolidone). The type of adsorption was found to be physical, which is supported by the enthalpy of adsorption as well as by IR spectra. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2482‐2490, 2004     

Silver‐ and gold‐labeled colloidal and crosslinked glycopolymers based on glycyl glycosynthons and maleic anhydride copolymers for lectin binding

A simple, convenient, and inexpensive technique for preparing lectin‐specific nanogold‐ and silver‐labeled colloidal and crosslinked neoglycoconjugates, based on maleic anhydride copolymers, was developed. Water‐soluble nanogold‐ and silver‐labeled glyconanoparticles were obtained in two steps: (1) introduction of free N‐acetyl‐D‐glucosamine or glycyl‐spacered glycosynthons—β‐N‐glycyl‐N‐acetyl‐D‐glucosamine or β‐N‐glycyl‐lactose—into poly(ethylene‐alt‐maleic anhydride) or poly(N‐vinylpyrrolidone‐alt‐maleic anhydride) and (2) labeling in situ the thus‐obtained glycopolymers with gold or silver nanoparticles. Lectin sorbents were synthesized from glycyl‐spacered glycosynthons and spherical, granulated, crosslinked maleic anhydride copolymers in an aqueous system without any condensing agents. Thus, maleic anhydride copolymer was used solely, without any preliminary modification of the polymer, as a matrix for crosslinking, for specific ligand binding, and as metal nanoparticles as a stabilizing cover. The resulting colloidal gold or silver glyconanoparticles were used as lectin sensors (in a dot‐blot analysis of lectins) and as crosslinked neoglycoconjugates for lectin sorption studies. The corresponding gold‐ or silver‐labeled water‐soluble glyconanoparticles and crosslinked neoglycoconjugates manifested high activity and specificity in all tests with a series of β‐D‐GlcNAc‐specific and β‐D‐Gal‐specific lectins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44718.     

Kinetics and reaction mechanism of template polymerization investigated by conductimetric measurements. Part 3. Radical polymerization of acrylic acid in the presence of poly(N‐vinylpyrrolidone)

Conductimetry was used for monitoring the radical polymerization of a weak electrolyte (acrylic acid) in aqueous solution and for determination of the kinetic parameters of the reaction (reaction order with respect to monomer, activation energy). The results obtained were consistent with those determined by other techniques (such as dilatometry) or expected from theory. Dilatometric and conductimetric measurements were also used to study the template polymerization of acrylic acid onto poly(N‐vinylpyrrolidone). Results indicate that the reaction proceeds according to a pick‐up mechanism. Complexes between poly(acrylic acid) and poly(N‐vinylpyrrolidone) were always isolated in equimolar composition of the two polymers, regardless of the polymerization mixture composition. Spectroscopic evidence of the existence of strong interaction and intimate mixing of the two polymers in the complexes was found. An influence of the template molecular weight on the chain length of the forming poly(acrylic acid) was detected by means of viscometry. © 2000 Society of Chemical Industry     

Semi‐interpenetrating networks based on poly(N‐isopropyl acrylamide) and poly(N‐vinylpyrrolidone)

Three series of novel semi‐interpenetrating polymer networks, based on crosslinked poly(N‐isopropylacrylamide), PNIPA, and different amounts of the linear poly(N‐vinylpyrrolidone), PVP, were synthesized to improve the mechanical properties and thermal response of PNIPA gels. The effect of the incorporation of the linear PVP into the temperature responsive networks on the temperature‐induced transition, swelling/deswelling behavior, and mechanical properties was studied. Polymer networks with four different crosslinking densities were prepared with varying molar ratios (25/1 to 100/1) of the monomer (N‐isopropylacrylamide) to the crosslinker (N,N′‐methylenebisacrylamide). The hydrogels were characterized by determination of the equilibrium degree of swelling, the dynamic shear modulus and the effective crosslinking density, as well as tensile strength and elongation at break. Furthermore, the deswelling kinetics of the hydrogels was studied by measuring their water retention capacity. The inclusion of the linear hydrophilic PVP in the PNIPA networks increased the equilibrium degree of swelling. The tensile strength of the semi‐interpenetrating networks (SIPNs) reinforced with linear PVP was higher than that of the PNIPA networks. The elongation at break of these SIPNs varied between 22% and 55%, which are 22 – 41% larger than those for pure PNIPA networks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Sorption properties of polymers based on N‐substituted maleimides

Physicochemical and functional properties of 2,2‐diallyl‐1,1,3,3‐tetraethylguanidinium chloride copolymers with N‐(n‐carboxyphenyl)maleimide, of N‐vinylpyrrolidone with N‐(n‐carboxyphenyl)maleimide, and of N‐vinylpyrrolidone with N‐phenylmaleimide have been investigated. Specific surface area and porosity of the copolymers under investigation have been determined by using the low‐temperature adsorption method. Electron microscope investigations in surfaces of the polymers have evinced that all of them have a spongy microstructure, the N‐vinylpyrrolidone copolymer with N‐(n‐carboxyphenyl)maleimide being the most homogeneous of these. Sorption capacity of the copolymers toward Re(VII) ions has been investigated. The process is described by the Langmuir isotherm. The pH is the most important parameter for sorption process of Re(VII). In the conjoint presence of Re(VII) and Mo(VI) in a solution of acid and ammoniac mediums, rhenium can be separated from molybdenum by using the sorbents under investigation at pH > 4.5 or at hydrochloric acid concentrations 0.1 mol L^?1 and more. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds

A series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry     

Synthesis and characterization of novel optically active poly(imide–urethane)s derived from N,N′‐(pyromellitoyl)‐bis‐(L‐leucine) diisocyanate and aromatic diols

N,N′‐(Pyromellitoyl)‐bis‐(L ‐leucine) diacid was reacted with ethyl chloroformate in the presence of triethylamine followed by reaction with activated sodium azide and gave N,N′‐(pyromellitoyl)‐bis‐(L ‐leucine) diacylazide in high yield. This diacylazide was heated in dry benzene and gave the unstable N,N′‐(pyromellitoyl)‐bis‐(L ‐leucine) diisocyanate ( 5 ) in quantitative yield. Thus, diisocyanate 5 was generated in situ and polycondensation reaction of this monomer with several aromatic diols, such as 4,4′‐dihydroxybiphenyl, 1,4‐hydroquinone, bisphenol A, phenolphthalein and 1,4‐dihydroxyanthraquinone, was performed in dry toluene under refluxing in the presence of 1,4‐diazabicyclo[2.2.2]octane (triethylenediamine) as a catalyst. The polymerization reactions proceeded within 48 h, producing a series of optically active poly(imide–urethane)s with good yield and moderate inherent viscosity in the range 0.18–0.28 dl g^?1. All of the above polymers were fully characterized by infrared spectra, elemental analyses and specific rotation. Some structural characterization and physical properties of these optically active poly(imide–urethane)s are reported Copyright © 2003 Society of Chemical Industry     

Synthesis and characterization of biodegradable block copolymer pluronic‐b‐poly(L‐lysine)

This study presented the investigations on the synthesis of a novel biodegradable block copolymer of pluronic‐b‐poly(L ‐lysine) (pluronic‐b‐PLL), which combined the characteristics of aliphatic polyester and poly(amino acids). The synthesis work started with end‐capping of pluronic with N‐t‐butoxycarbonyl‐L ‐phenylalanine using dicyclohexylcarbodiimide in the presence of 4‐dimethylaminopyridine, followed by a deprotection process to obtain the amino‐terminated pluronic; the new primary amino group in the modified pluronic initiated ring‐opening polymerization of amino acid N‐carboxyanhydride, which afforded the pluronic‐b‐poly(N^ε‐(Z)‐L ‐lysine) block copolymer. Finally, removal of the side‐chain N^ε‐(carbonybenzoxy) end protecting groups yields the block copolymer of pluronic‐b‐PLL. The products were characterized by ¹H‐NMR, FTIR, DSC, and GPC. The block copolymer micelle containing the anticancer drug paclitaxel was prepared by the double emulsion method. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of novel optically active poly(amide–imide)s containing N,N′‐(pyromellitoyl)‐bis‐L‐valine diacid chloride and 5,5‐disubstituted hydantoin derivatives under microwave irradiation

Pyromellitic dianhydride (1,2,4,5‐benzenetetracarboxylic acid 1,2,4,5‐dianhydide) was reacted with L ‐valine in a mixture of acetic acid and pyridine (3:2) at room temperature, and then was refluxed at 90–100 °C, N,N′‐(pyromellitoyl)‐bis‐L ‐valine diacid was obtained in quantitative yield. The imide–acid was converted to N,N′‐(pyromellitoyl)‐bis‐L ‐valine diacid chloride by reaction with thionyl chloride. Rapid and highly efficient synthesis of a number of poly(amide–imide)s was achieved under microwave irradiation using a domestic microwave oven by polycondensation of N,N′‐(pyromellitoyl)‐bis‐L ‐valine diacid chloride with six different derivatives of 5,5‐disubstituted hydantoin compounds in the presence of a small amount of a polar organic medium that acts as a primary microwave absorber. A suitable organic medium was o‐cresol. The polycondensation proceeded rapidly, compared with conventional melt polycondensation and solution polycondensation and was almost completed within 8 min, giving a series of poly(amide–imide)s with inherent viscosities in the range 0.15–0.36 dl g^?1. The resulting poly(amide–imide)s were obtained in high yield and are optically active and thermally stable. All of the above compounds were fully characterized by Fourier‐transform infrared (FT‐IR) spectroscopy, elemental analysis, inherent viscosity (η_inh) measurements, solubility testing and specific rotation measurements. The thermal properties of the poly(amide–imide)s were investigated by using thermogravimetric analysis. Copyright © 2004 Society of Chemical Industry     

Interaction of a new anesthetic drug richlocain with linear and weakly crosslinked poly‐N‐vinylpyrrolidone

The properties of complexes of richlocain, a new local anesthetic drug, with linear and weakly crosslinked poly‐N‐vinylpyrrolidone were investigated with changes in media properties of pH, temperature, and solvent thermodynamic quality. The kinetics and activation energy of drug release from the gel matrix were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2977–2981, 2003