Synthesis and characterization of chitosan derivatives carrying galactose residues

A series of water‐soluble chitosan derivatives, carrying galactose residues, were synthesized by using an alternative method in which the galactose groups were introduced into amino groups of the derivatives. First, hydroxyethyl chitosan (HECS) and hydroxypropyl chitosan (HPCS) were synthesized under alkaline conditions by using chitosan and propylene or chitosan and ClCH₂CH₂OH as the starting materials, respectively. Then lactobionic acid was added into the systems so as to form galactosylated HECS (Gal‐HECS) and galactosylated HPCS (Gal‐HPCS) with substitution degrees of 53 and 47%, respectively. Lactosaminated HPCS (Lac‐HPCS) and Lactosaminated HECS (Lac‐HECS) were obtained with substitution degrees of 42 and 38%, respectively, by the reductive amination of the mixtures of lactose and HECS or lactose and HPCS with potassium borohydride present in the reaction. The chemical structures of new chitosan derivatives were characterized by FTIR, ¹H NMR, ¹³C NMR, and elemental analysis. Some physical properties were also analyzed by wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). The novel chitosan derivatives carrying galactose residues may be used as additives for hepatic targeting delivery. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2161–2167, 2005     

Synthesis and degradation of agar‐carbomer based hydrogels for tissue engineering applications

Hydrogels studied in this investigation, synthesized starting from agarose and Carbomer 974P, were chosen for their potential use in tissue engineering. The strong ability of hydrogels to mimic living tissues should be complemented with optimized degradation time profiles: a critical property for biomaterials but essential for the integration with target tissue. In this study, chosen hydrogels were characterized both from a rheological and a structural point of view before studying the chemistry of their degradation, which was performed by several analysis: infrared bond response [Fourier transform infrared (FT‐IR)], calorimetry [differential scanning Calorimetry (DSC)], and % mass loss. Degradation behaviors of Agar‐Carbomer hydrogels with different degrees of crosslinkers were evaluated monitoring peak shifts and thermal property changes. It was found that the amount of crosslinks heavily affect the time and the magnitude related to the process. The results indicate that the degradation rates of Agar‐Carbomer hydrogels can be controlled and tuned to adapt the hydrogel degradation kinetics for different cell housing and drug delivery applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Interfacial properties of chitosan and nonylphenol polyoxyethylene ether

Nonylphenols are water‐soluble surfactants that are used extensively in industry and are found in many consumer products. Nonylphenol polyoxyethylene ether (known commercially as TX‐100), which is one of the most popular members of this family, has a detrimental effect on the environment. Adding chitosan to a solution of TX‐100 reduces the amount of surfactant required while maintaining its surface activity. We evaluated the interfacial properties, including the surface tension, contact angle, and particle size, as well as the fluorescence and Fourier transform infrared spectra of various test solutions prepared from three stock solutions: (1) chitosan dissolved in dilute acetic acid, (2) TX‐100 dissolved in deionized water, and (3) a mixed chitosan/TX‐100 solution. Previous results revealed that low concentrations of TX‐100 are relatively harmless to the environment; in this study, we found that its surface activity at a higher concentration was equal to that of its chemical mixture with chitosan. In addition, we found that the presence of chitosan improved the stability of emulsions of TX‐100. The micellar particles were small, and the stability of the emulsion was maximized at a TX‐100 to chitosan ratio of 7 : 3. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Antimicrobial and physical properties of woolen fabrics cured with citric acid and chitosan

In this study, we used citric acid (CA) as a crosslinking agent, mixed with biopolymer molecular chitosan, to perform a pad–dry–cure treatment on woolen fabrics to study its antimicrobial effects and physical properties with the help of IR spectroscopy, electron microscopy, and differential thermal analysis. From the experimental results, we learned that CA did not crosslink with the woolen fibers if the woolen fabrics were not oxidized by potassium permanganate and that after oxidization, CA produced esterification with the ? OH group of the wool and chitosan and transamidation with the? NH₂ group of the wool to form a crosslink. The surface crosslinks of the oxidized woolen fibers were relatively coarse, which is undesirable for shrink‐proofing and yet beneficial for the antimicrobial and antiseptic effects of the woolen fabrics. It had a negative effect on the fabric softness, yellowness, stretching resistance, and elongation percentage. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1999–2007, 2004     

Antifungal properties of chitosan salts in laboratory media

Some aliphatic carboxylic acids were used to produce chitosan (CS) salts by reaction with CS, and their antifungal activity against three kinds of phytopathogens was estimated by hypha measurement in vitro. The fungicidal assessment showed that all of the CS salts had excellent activity against the tested fungi. Their inhibitory indices were 41.15–64.15, 56.25–76.56, and 35.94–68.75% for Cladosporium cucumerinum (Ell.) et Arthur, Monilinia fructicola (Wint.) Honey, and Fusarium oxysporum sp. Cucumis sativus L., respectively, at 1000 μg/mL; these indices were higher than that of CS. It was confirmed that the amino groups' protonation was important for the antifungal activity of CS derivatives. The substituted groups with stronger electronegativity drew more electrons from the nitrogen atoms in the derivative molecules, which relatively strengthened the polycationic character of the CS derivatives. Therefore, the antifungal activity of the CS salts was improved. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide) as a novel cellulose‐based superabsorbent

A new cellulose‐based superabsorbent polymer, carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide), was prepared by the free‐radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N′‐methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose‐graft‐poly(acrylic acid‐co‐acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382–1388, 2007     

Silver‐nanoparticle‐loaded chitosan lactate films with fair antibacterial properties

Food quality and safety are major concerns in the food industry. Antimicrobial packaging can be considered an emerging technology that could have a significant impact on life and food safety. Antimicrobial agents in food packaging can control the microbial population and target specific microorganisms to provide greater safety and higher quality products. In this work, a lactic acid grafted chitosan film was synthesized. Silver nanoparticles were loaded into the chitosan lactate (CL) film by equilibration in a silver nitrate solution, which was followed by citrate reduction. The presence of silver nanoparticles was confirmed with transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis of the film. The silver‐nanoparticle‐loaded CL film was investigated for its antimicrobial properties against Escherichia coli. This newly developed material showed strong antibacterial properties and thus has potential for use as an antibacterial food‐packaging material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Interactions in blends containing chitosan with functionalized polymers

The phase behavior of blends containing chitosan with poly(vinyl‐alcohol) (PVA) and poly(2‐hidroxyethyl methacrylate) (P2HEM) was analyzed. Blends were obtained by casting from acetic acid solution (HAc) and 1,1,1,3,3,3 hexafluoro‐2‐propanol (HF2P) and studied by DSC, FT‐IR, and TGA. The phase behavior of the blends of chitosan with PVA and P2HEM, studied by DSC, shows that the systems behave as one‐phase systems in HAc as well as in HF2P according to the DSC results. According to the results of FT‐IR analyses of the different absorptions of the blends, relative to the pure components, they show an important shift that is considered evidence of an interaction between the components of the blends. The thermogravimetric analysis of the blends and the pure components shows that the temperature for thermal degradation of the blends is higher that that of the pure components, irrespective of the solvent casting from which the mixture was obtained. These results are interpreted as the formation of a new product that corresponds to a compatible polymer blend. The compatibilization of these systems is attributed to strong interactions, like hydrogen bonds formation between the functionalized polymers and chitosan, due to the presence of interacting functional groups in all the polymers studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1953–1960, 2005     

Preparation and characterization of a positive thermoresponsive hydrogel for drug loading and release

A positive thermoresponsive hydrogel composed of poly(acrylic acid)‐graft‐β‐cyclodextrin (PAAc‐g‐β‐CD) and polyacrylamide (PAAm) was synthesized with the sequential interpenetrating polymer network (IPN) method for the purpose of improving its loading and release of drugs. The structure and properties of the PAAc‐g‐β‐CD/PAAm hydrogel (IPN hydrogel) were characterized with Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and swelling measurements. FTIR studies showed that the IPN hydrogel was primarily composed of an IPN of PAAc‐g‐β‐CD and PAAm. The data from DSC and swelling measurements indicated that the phase‐transition temperature or upper critical solution temperature (UCST) of the IPN hydrogel was approximately 35°C. Through the measurement of the temperature dependence of the swelling, increases in the UCST and non‐sensitivity to changes in the salt concentration were observed for the IPN hydrogel versus the normal IPN hydrogel poly(acrylic acid)/PAAm (without β‐cyclodextrin). Furthermore, the swelling/deswelling kinetics of the IPN hydrogel also exhibited an improved controllable response rate versus the normal IPN hydrogel. Ibuprofen (IBU) was chosen as the model drug for examining loading and release from the IPN hydrogel. The experimental data proved that the IPN hydrogel provided a positive drug release pattern; the IBU released faster at 37°C than at 25°C, and improved drug loading and controlled release were achieved by the IPN hydrogel versus the normal IPN hydrogel. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

RF sputter deposition of poly(tetrafluoroethylene) films as masking materials for silicon micromachining

Polymers have been studied extensively because of their wonderful array of properties. Their properties can be tailored by many means and can be made useful in many ways. Polymers can be crosslinked or branched and can provide different properties, such as conduction and passivation. This study dealt with the RF sputter deposition of poly(tetrafluoroethylene) (PTFE) films with the aim of using them as masking materials during the fabrication of various micromachined structures. The films were deposited on silicon substrates at different plasma powers (100, 150, and 200 W) for a constant deposition time (60 min). To test the masking properties, the deposited films were immersed in a 20 wt % aqueous KOH solution at 80°C for 60 min. The films showed lower contact angles and interfacial tension, and this indicated good adhesion of the films to the silicon substrates. Good adhesion is an essential quality of masking materials during micromachining. The structural properties of the as‐deposited and etched films were studied with Fourier transform infrared and X‐ray photoelectron spectroscopy. These indicated that the bonding groups and binding energies of C? F and C? CF matched the reported values well. Furthermore, the presence of C? F and C? CF bonds, even after the etching of silicon substrates in highly alkaline KOH solutions for 60 min, showed that the PTFE films remained unchanged in the etchant and, therefore, could function as good masking materials during the fabrication of micromachined structures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1183–1192, 2004     

Synthesis of thermosensitive copolymer beads containing pyridinium groups and their antibacterial activity

Thermosensitive 4VP‐NIPAAm‐4G copolymer beads containing pyridyl groups were first prepared by suspension copolymerization of 4‐vinylpyridine (4VP), N‐isopropylacrylamide(NIPAAm), and tetraethylene glycol dimethacrylate (4G; crosslinking reagent) in a saturated Na₂SO₄ aqueous solution in the presence of surfactant and MgCO₃ as dispersants. Then the copolymer beads containing pyridinium groups were obtained by the quaternization of the copolymer beads with various alkyl iodides (CH₃I, C₄H₉I, C₈H₁₇I) in N,N‐dimethylformamide. The 4VP‐NIPAAm‐4G (15 : 97 : 3) copolymer bead and the 4VP‐NIPAAm‐4G copolymer beads quaternized with butyl iodide exhibited high thermosensitivity in water, although the 4VP‐NIPAAm‐4G copolymer beads quaternized with methyl iodide or octyl iodide hardly exhibited thermosensitivity. All the quaternized copolymer beads exhibited antibacterial activity against Escherichia coli (E. coli), although the 4VP‐NIPAAm‐4G copolymer bead did not. In particular, the copolymer bead quaternized with butyl iodide exhibited the highest antibacterial activity against E. coli at 30°C. It was also found that the antibacterial activity of the quaternized 4VP‐NIPAAm‐4G copolymer beads was greatly affected by not only chain length of alkyl groups in alkyl iodides, with which the 4VP‐NIPAAm‐4G copolymer beads were quaternized, but also by temperature of the solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characterization of acrylic resins and fluoroelastomer blends as potential materials in stone protection

Films of blends of Paraloid® B72 (copolymer of ethyl methacrylate and methyl acrylate) and Tecnoflon NM® (copolymer of vinylidene fluoride and hexafluoropropene) with different compositions were investigated by means of FT‐IR spectroscopy and FT‐IR microspectroscopy before and after UV and thermal treatments. Preliminary results of DSC measurements are also reported. Paraloid B72 has been extensively applied as a protective agent for stone since the 1950s. More recently considerable research has also been carried out on the application of fluorinated polymers in the field of stone conservation, eg the fluoroelastomer Tecnoflon®. A high content of Tecnoflon with respect to Paraloid increases the stability of the blends when they are submitted to UV radiation and thermal treatments. A THF solution of a blend of this kind was successfully applied to a marble surface of the Saint Maria Cathedral in Lucca, Tuscany, Italy. The changes in the properties of such mixtures with different compositions can offer new possibilities in developing suitable protective materials. © 2000 Society of Chemical Industry     

Carboxymethyl tamarind: Synthesis,characterization and its application as novel drug‐delivery agent

Carboxymethylated tamarind (CMT) has been synthesized by reacting tamarind kernel powder (TKP) with sodium salt of monochloro acetic acid (SMCA) in the presence of sodium hydroxide. This new material was characterized by a variety of materials characterization techniques, namely intrinsic viscosity measurement, FTIR spectroscopy, ¹³C NMR spectra, thermal studies (TGA and DTA), static light scattering (SLS) technique for determination of weight average molecular weight and elemental analysis (C, H, N and O). The material thus developed was studied for its suitability as a matrix for controlled drug delivery. The kinetics of Drug release was also undertaken. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of poly(p‐phenylene diamine) and its corrosion inhibition effect on iron in 1M HCl

Water‐soluble poly(p‐phenylene diamine) was chemically synthesized. Its corrosion inhibition performance was evaluated for iron corrosion in 1M HCl at various concentrations, and the results were compared with that of the monomer. The corrosion inhibition properties were evaluated by polarization techniques and electrochemical impedance spectroscopy. The results showed that poly(p‐phenylene diamine) was a more efficient corrosion inhibitor than the monomer and gave an 85% inhibition efficiency at a concentration of 50 ppm, whereas the monomer gave an efficiency of 73% at 5000 ppm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Water/ethanol pervaporation performance of asymmetric polyelectrolyte complex membrane constructed by the diffusion of poly(acrylic acid) in chitosan membrane

Asymmetric polyelectrolyte complex (PEC) membranes composed of chitosan membrane and absorbed poly(acrylic acid) (PAA) were constructed. Absorption and therefore PEC formation were performed by bringing a chitosan membrane into contact with a PAA aqueous solution. The mean molecular weight (MW) of PAA employed was 5,000, 25,000 or 250,000. Absorption of PAA and asymmetry of PEC membranes were confirmed and evaluated by Fourier transform infrared (FTIR) spectra and electron spectroscopy for chemical analysis (ESCA). The absorption quantity of PAA decreased while the water selectivity of the PEC membrane increased with an increase in the MW of constituent PAA. In a pervaporation experiment, the water selectivity of the membrane was so high that no ethanol was detected by gas chromatography (GC). Such selectivity was attained by just a small quantity of PEC formation at the surface of the chitosan membrane. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 265–271, 2002     

Preparation and multifunctional application of meso‐chitosan for the woolen process

This study used chitosan deacetylated to different degrees to process woolen fabrics via the nanometrization of sodium hydroxide of different concentrations. The analysis and determination of the bacterial resistance, shrink resistance, Fourier transform infrared, and dyeability were then carried out for the processed substances. The particle diameter was measured with light scattering and scanning electron microscopy. It was then reduced with 5% and higher concentrations of NaOH, in which the particle diameter was 150–750 nm. As for bacterial resistance, the processed cloth that was not oxidized by H₂O₂ had better bactericidal and bacteriostatic effects than the cloth that underwent the oxidation process. Chitosan and meso‐chitosan had a bacterial‐resistance effect on the woolen fabrics. The processed cloth also had a better shrink‐resistance rate, but the effect of nanometrization was not obvious. For the dyeability of the woolen fabrics, meso‐chitosan was better than chitosan. The higher degree of deacetylation of chitosan slightly improved the dyeability. The dyeability increased a little as the temperature of the curing treatment rose and the time of the curing treatment was extended. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4080–4086, 2007     

Durable antimicrobial treatment of cotton fabrics using N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride and polycarboxylic acids

N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTCC), a water‐soluble chitosan quaternary ammonium derivative, was used as an antimicrobial agent for cotton fabrics. HTCC has a lower minimum inhibition concentration (MIC) against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli compared to that of chitosan; however, the imparted antimicrobial activity is lost on laundering. Thus crosslinking agents were utilized to obtain a durable antimicrobial treatment by immobilizing HTCC. Several crosslinkers such as dimethyloldihydroxyethylene urea (DMDHEU), butanetetracarboxylic acid (BTCA), and citric acid (CA) were used with HTCC to improve the laundering durability of HTCC treatment by covalent bond formation between the crosslinker, HTCC and cellulose. The polycarboxylic acid treatment was superior to the DMDHEU treatment in terms of prolonged antimicrobial activity of the treated cotton after successive laundering. Also, the cotton treated with HTCC and BTCA showed improved durable press properties without excessive deterioration in mechanical strength or whiteness when compared to the citric acid treatment. With the addition of only 0.1% HTCC to BTCA solutions, the treated fabrics showed durable antimicrobial activity up to 20 laundering cycles. The wrinkle recovery angle and strength retention of the treated fabrics were not adversely affected with the addition of HTCC. Therefore, BTCA can be used with HTCC in one bath to impart durability of antimicrobial activity along with durable press properties to cotton fabric. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1567–1572, 2003     

Interpolymer interactions and miscibility in poly(n‐butyl methacrylate‐co‐methacrylic acid)/poly(styrene‐co‐N,N‐dimethyl acrylamide) blends

The miscibility of poly(n‐butyl methacrylate‐co‐methacrylic acid) containing 18 mol % methacrylic acid (BMAM‐18) and poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 17 mol % N,N‐dimethyl acrylamide (SAD‐17) was investigated with viscometry, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The DSC analysis showed a single glass‐transition temperature for all the blends, indicating that these copolymers were miscible over the entire composition range. The glass‐transition temperatures of these blends were higher than those calculated with the additivity rule. This was characteristic of the presence of specific interactions. The interactions between BMAM‐18 and the tertiary amide of SAD‐17 were studied with FTIR spectroscopy, which revealed that hydrogen‐bonding interactions occurred between the hydroxyl groups of BMAM‐18 and the carbonyl amide of SAD‐17. A new band characterizing these interactions appeared around 1613 cm^?1. The quantitative results showed that the fraction of the associated amide increased with an increase in the amount of the acidic BMAM‐18 copolymer. Although BMAM‐18 and SAD‐17 led to homogeneous solutions in butan‐2‐one, as the concentration of N,N‐dimethyl acrylamide increased to 32 mol % [as within the poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 32 mol % N,N‐dimethyl acrylamide], complexation occurred when this latter compound was mixed with BMAM‐18 in butan‐2‐one. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2717–2724, 2006     

Synthesis and characterization of poly(N‐methyl aniline) doped with sulphonic acids: Their application as humidity sensors

Single step chemical polymerization of N‐methyl aniline was carried out by using ammonium persulphate as an oxidizing agent. The conducting emeraldine salt phase of the polymers using camphor sulfonic acid and p‐toluene sulfonic acid as dopants was made by a direct process. The polymers were characterized by UV‐vis and FTIR spectroscopy, scanning electron microscopy, TGA, and conductivity measurements. The synthesized polymers were found to have very good physicochemical properties and good electrical conductivity. Conductivity measurements have shown “thermal activated behavior.” The change in resistance with respect to % relative humidity (RH) was observed, when pressed pellets of the polymer were exposed to the broad range of humidity (ranging between 20 and 100% RH). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 812–820, 2006     

Synthesis and characterization of poly(N‐isopropylacrylamide)s initiated with siloxane oligomer–(NH4)2Ce(NO3)6 redox pair

Poly(N‐isopropylacrylamide)s (PNIPAAM)s were synthesized via free‐radical polymerization using a ceric ammonium nitrate, Ce(IV)–α‐ω‐dihydroxy(polydimethylsiloxane) (Tegomer H‐Si 2111, PDMS) redox pair in hexane at 30°C in a nitrogen atmosphere. The dependence of the initiation and termination steps on the [NIPAAM]/[Ce(IV)] and [NIPAAM]/[PDMS] ratios were studied using gravimetry and FTIR, ¹H‐NMR, UV‐vis, and GFAA spectroscopy techniques. Gravimetric results indicated that, in the case of high concentrations of PDMS, the percentage of the solid portions of the products decreased while the amount of the oligomeric NIPAAM chains increased, that is, as the amount of PDMS in hexane was increased, the number of the short NIPAAM chains having PDMS segments at the two ends, also increased. UV‐vis results showed that the LCST of PNIPAAM initiated with Ce(IV) alone was higher than those of the ones that were synthesized using common initiator systems such as an ammonium persulfate–N,N,N′,N′‐tetramethylethylenediamine redox pair and azobis(isobutyronitrile). Further, it was observed that both siloxane blocks and ? NH? groups forming coordination bonds with free Ce(IV) ions and/or metal–ligand complexes had an important effect on the aggregation process of the chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1248–1254, 2003