Synthesis,characterization and antibacterial activity of quaternized <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">O</Emphasis>-(2-carboxyethyl) chitosan

N,O-(2-carboxyethyl)chitosan (N,O-2-CEC) was prepared from chitosan with 3-chloropropionic acid as modifying agent and NaOH as catalyst. Different quaternary ammonium groups were introduced into N,O-2-CEC by the reaction between N,O-2-CEC and different 2,3-epoxypropyl trialkyl ammonium chlorides in the presence of 25% NaOH aqueous solution, and obtained different quaternized N,O-2-carboxyethyl chitosans (QCECs). Structures of QCECs were characterized by FT-IR, ¹HNMR and gel permeation chromatography (GPC). Antimicrobial activity of QCECs was evaluated against a gram-negative bacterium Escherichia coli and a gram-positive bacterium Staphylococcus aureus. Compared with N,O-2-CEC and quaternized chitosans, the QCECs had much stronger antimicrobial activity, which increased with increasing chain length of the alkyl in the quaternary ammonium groups. The presence of benzyl in quaternary ammonium groups could endow QCECs with much better antimicrobial activity.     

Antimicrobial properties of bio‐inspired poly(4‐vinyl‐2‐pyridone) and its N‐alkylated cationic derivatives

Developing new antimicrobial polymers and designing new antimicrobial materials are important research areas for overcoming bacterial resistance. In the present study a new polymer, poly(4‐vinyl‐2‐pyridone), having bioactive structure analogous to that of naturally occurring heterocyclic compounds, was synthesized from 4‐vinylpyridine following a simple protocol. To augment the antibacterial properties of the synthesized polymer, N ‐alkylation of the heterocyclic pyridone moieties was achieved with ethylene chlorohydrin (2‐chloroethanol) to generate choline analogous structure. Also, its N ‐butylated analogue was synthesized as a reference compound to study structure–activity relationship. Structures of the polymers were confirmed using various characterization techniques. Antimicrobial efficacy of the polymers was determined using the minimum inhibitory concentration method in parallel experiments. The test microorganisms used were a Gram (+) bacterium (Staphylococcus epidermidis ), Gram (?) bacteria (Salmonella typhi , Pseudomonas aeruginosa and Escherichia coli ) and a fungus (Candida albicans ). Both the polymer derivatives are far more effective antimicrobial agents than the pristine polymer. Trends in the antimicrobial efficacy of these polymers correlate with their zeta potential values. © 2016 Society of Chemical Industry     

Synthesis and properties of polymeric biocides based on poly(ethylene‐co‐vinyl alcohol)

Poly(ethylene‐co‐vinyl acetate) with 55 wt % vinyl acetate units (EVA55) was cryogenically ground and saponified in KOH/ethanol solution to obtain poly(ethylene‐co‐vinyl alcohol) (EVOH55). Polymeric antimicrobial agents were synthesized by reacting three antimicrobial agents, 4‐aminobenzoic acid (ABA), salicylic acid (SA), and 4‐hydroxy benzoic acid (HBA) with EVOH55. The polymers became more flexible and exhibited lower melting peak temperature and heat of fusion as the content of the chemically bound ABA, SA, and HBA units increased. These phenomena appeared more significant in the order of ABA < HBA < SA. S. aureus, Gram‐positive bacterium, was more susceptible to the polymeric antimicrobial agents than P. aeruginesa, Gram‐positive bacterium. The antimicrobial activity increased in the order of EVOH55‐HBA < EVOH55‐ABA < EVOH‐SA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 765–770, 2004     

Antimicrobial poly(N‐vinyl‐2‐pyrrolidone‐alt‐maleic anhydride)/poly(ethylene imine) macrocomplexes

The antimicrobial polymer/polymer macrocomplexes were synthesized by radical alternating copolymerization of N‐vinyl‐2‐pyrrolidone with maleic anhydride [poly(VP‐alt‐MA)] with 2,2′‐azobis‐isobutyronitrile as an initiator at 65°C in dioxane solutions under nitrogen atmosphere, and interaction of prepared copolymer with poly(ethylene imine) (PEI) in aqueous solutions. The susceptibility of some Gram‐negative (Salmonella enteritidis and Escherichia coli) and Gram‐positive (Staphylococcus aureus and Listeria monocytogenes) bacteria to the alternating copolymer and its PEI macrocomplexes with different compositions in microbiological medium was studied using pour‐plate technique. All the studied polymers, containing biologically active moieties in the form of ionized cyclic amide, and macrobranched aliphatic amine groups and acid/amine complexed fragments, were more effective against L. monocytogenes than those for Gram‐positive S. aureus bacterium. This fact was explained by different surface layer structural architectures of biomacromolecules of tested bacteria. The resulting polymeric antimicrobial materials are expected to be used in various areas of medicine and food industry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5841–5847, 2006     

One pot blending of biopolymer‐TiO2 composite membranes with enhanced mechanical strength

A biopolymer‐TiO₂ composite membrane was prepared by blending of N‐[(2‐hydroxy‐3‐trimethylammonium) propyl] chloride chitosan and cellulose acetate with nano‐TiO₂ particles as the introduced inorganic components. It was verified that the amino groups (? NH₂) of chitosan (CTS) were partly grafted by stronger hydrophilic group ? according to the ¹H‐nuclear magnetic resonance spectra of N‐[(2‐hydroxy‐3‐trimethylammonium) propyl] chloride chitosan and attenuated total reflectance Fourier transform infrared spectroscopy. The structure, microcosmic morphology, water flux, swelling properties, and thermal stability of the composite membranes were characterized. With the mass ratio of cellulose acetate to CTS being 50 wt %, the mole ratio of CTS to glycidyl trimethylammonium chloride being 1 : 1, and drying temperature being 60°C in 70% acetic acid, the formed biopolymer‐TiO₂ composite membranes exhibited enhanced mechanical strength (84.29 MPa), lower swelling degree (101.36%), and improved antibacterial activity against Gram‐negative Escherichia coli (Rosetta and DH5α) and Gram‐positive Bacillus subtilis. The existence of nano‐TiO₂ particles and the introduction of stronger cationic group synergistically improved the antibacterial properties of the biopolymer‐TiO₂ composite membranes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42732.     

Study on superabsorbent composites. XXI. Synthesis,characterization and swelling behaviors of chitosan‐g‐poly(acrylic acid)/organo‐rectorite nanocomposite superabsorbents

A novel chitosan‐g‐poly(acrylic acid)/organo‐rectorite (CTS‐g‐PAA/OREC) nanocomposite superabsorbent was synthesized by aqueous polymerization using N, N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Rectorite was organified with four different degree of hexadecyltrimethyl ammonium bromide, and the organification of rectorite was proved by FTIR and XRD. The effect of organification degree of rectorite on water absorbency of CTS‐g‐PAA/OREC with different organo‐rectorite content was investigated. The swelling behaviors in distilled water and various pH solutions were also studied. The results from IR spectroscopy and XRD data show that acrylic acid had been grafted polymerization with chitosan and organo‐rectorite and formed nanocomposite. Introducing organo‐rectorite into the CTS‐g‐PAA polymeric network can improved water absorbency and swelling rate of CTS‐g‐PAA/OREC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

N‐alkylation of chitosan by β‐halopropionic acids in the presence of various acceptors

N‐carboxyethylation of chitosan by β‐halopropionic acids in the presence of various proton and halogen ion acceptors was investigated. It has been observed that carboxyethylation of chitosan in aqueous medium is accompanied by the by‐processes of hydrolysis and dehydrohalogenation of the β‐halopropionic acids yielding β‐hydroxypropionic acid, bis(2‐carboxyethyl) ether, and acrylic acid. Degree of carboxyethyl substitution (DS) of chitosan and the relative rates of the by‐processes varied significantly depending on the conditions used and nature of the proton or halogen ion acceptor. At carboxyethylation of chitosan with the alkaline β‐bromopropionates, the DS increased in the order Cs⁺ < Rb⁺ < K⁺ ～ Na⁺ < Li⁺. For alkaline earth salts BrCH₂CH₂COOM_0.5 (M = Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺), the highest DS was obtained with strontium and barium salts, which could be subsequently removed from the reaction mixture by precipitation as sulfates. Among the organic bases applied (tetrabutylammonium hydroxide, triethylamine, trimethylamine, pyridine, 4‐N,N‐dimethylaminopyridine, 2,6‐lutidine, and 1,5‐diazabicyclo[4.3.0] non‐5‐ene), the highest DS was obtained using a moderately strong base triethylamine. For the halogen acceptors (Pb²⁺, Ag⁺, Tl⁺), the stoichiometrically highest DS was achieved in a system comprising iodopropionic acid plus Tl⁺ and a comparable conversion rate was obtained using also a combination of chloropropionic acid and Ag⁺. A novel alternative preparative approach—gel‐state synthesis—was suggested that provides for the highest DS at the optimum reaction conditions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Research on the preparation and antibacterial properties of 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan membranes with iodine

The 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan (ATU‐HPCS) was prepared by chitosan grafted hydroxypropyl and thiosemicarbazide through the method of “amino protection‐graft‐deprotection,” while the ATU‐HPCS gel membranes were obtained from gelatin and polyvinyl pyrrolidone as additives, and the ATU‐HPCS membranes with iodine (ATU‐HPCS‐I₂‐M) were prepared by adding the ethanol solution of iodine in the ATU‐HPCS gel membranes. The ATU‐HPCS‐I₂‐M were characterized to evaluate their potential applications as antibacterial materials. The iodine releasing rule of ATU‐HPCS‐I₂‐M showed a sustained‐release effect of iodine, the maximum emission was approximately 0.80%. The inhibition zone diameters of ATU‐HPCS‐I₂‐M against Staphylococcus aureus (as Gram‐positive bacteria) and Escherichia coli (as Gram‐negative bacteria) were both greater than 15 mm, it demonstrated significant antibacterial activity compared with the ATU‐HPCS gel membranes. The double effects of the biocompatibility of chitosan and the sustained‐release of iodine provided an ideal healing environment for wound surface. These properties have made ATU‐HPCS‐I₂‐M highly potential as a novel natural macromolecule antimicrobial material preventing the bacteria from burns, surgery wounds, etc. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40535.     

Synthesis and characterization of grafting β‐cyclodextrin with chitosan

Two new adsorbents [β‐cyclodextrin–chitosan (β‐CD–CTS) and β‐cyclodextrin‐6–chitosan (β‐CD‐6‐CTS)] were synthesized by the reaction of β‐cyclodextrin (β‐CD) with epoxy‐activated chitosan (CTS) and the sulfonation of the C‐6 hydroxyl group of β‐cyclodextrin with CTS, respectively. Their structures were confirmed by IR spectral analysis and X‐ray diffraction analysis, and their apparent amount of grafting was determined by ultraviolet spectroscopy. The adsorption properties of β‐CD‐CTS and β‐CD‐6‐CTS for p‐dihydroxybenzene were studied. The experimental results showed that the two new adsorbents exerted adsorption on the carefully chosen target. The highest saturated capacity of p‐dihydroxybenzene of β‐CD‐CTS and β‐CD‐6‐CTS were 51.68 and 46.41 mg/g, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 860–864, 2004     

Structural characterization and antimicrobial activity of chitosan (CS‐40)/nisin complexes

A complex of chitosan (CS‐40) and nisin (CS‐40/nisin) was prepared and characterized with Fourier transform infrared spectroscopy and thermal analysis (thermogravimetry, differential thermogravimetry, and differential scanning calorimetry). The results show that the complex formed mainly by electrostatic interaction between the protonated amino group in CS‐40 backbone with the carboxylate ion of nisin. Minimum inhibitory concentrations (MICs) were evaluated against Gram‐positive bacteria (Staphylococcus aureus, Bacillus subtilis, and Bacillus stearothermophilus), Gram‐negative bacteria (Escherichia coli, Salmonella enteritidis, and Proteus vulgaris), and fungi (Fusarium oxysporum). The results show that the CS‐40/nisin solution did inhibit or even more strongly inhibited the growth of all the tested microorganisms, whereas CS‐40 did not inhibit the growth of F. oxysporum and nisin did not inhibit the growth of Gram‐negative bacteria (E. coli, S. enteritidis, and P. vulgaris). The relative inhibition times of CS‐40/nisin solutions with different concentrations and ratios of CS‐40 and nisin were also investigated against the seven microorganisms. The results showed that CS‐40/nisin solutions with CS‐40/nisin concentration ratios of 0.05/0.005, 0.05/0.0025, 0.05/0.00125, and 0.025/0.0001% had higher antimicrobial activity against all tested bacteria and fungi. The relationship between complex formation and antimicrobial activity is discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of amphoteric N,O‐carboxymethyl hydroxypropyl chitosan by a two‐step reaction

A novel N,O‐carboxymethyl hydroxypropyl chitosan (HPCMS) derivative was prepared by a two‐step reaction. Water‐soluble hydroxypropyl chitosan (HPCS) with a degree of substitution of hydroxypropyl higher than 0.8 was first synthesized by the reaction of chitosan (CS) with propylene oxide (PO) with alkali as a catalyst. Then, amphoteric chitosan derivatives (HPCMS) with a degree of substitution of carboxymethyl ranging from 0.42 to 1.38 were prepared by the reaction of HPCS with chloroacetic acid in an aqueous solution with alkali as a catalyst. The structures of the polymers were characterized by Fourier transform infrared spectroscopy and NMR; this showed that the hydroxypropylation mainly occurred on the ? OH groups at the C‐6 of CS in the reaction of CS with PO. In the reaction of HPCS with chloroacetic acid, both the ? OH and ? NH₂ groups of HPCS were susceptible to the carboxymethylation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40460.     

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     

Synthesis of chitosan derivative with dual‐antibacterial functional groups and its antibacterial activity

The O‐fumaryl ester (OFTMCS) of N,N,N‐trimethyl chitosan (TMCS) has been synthesized as a water‐soluble chitosan (CS) derivative bearing dual‐functional groups, with the aim of discovering novel CS derivatives with good water solubility and enhanced the antibacterial activity compared with unmodified CS. OFTMCS was characterized by FT‐IR, ¹³C NMR, XPS, XRD and Zeta potential analyses. The XPS results indicated that the degree of substitution (DS) on the C₂‐NH₂ group of the CS was 0.78, and that the DS on its C₆‐OH group was 0.31. The TGA results showed that the thermal stability of OFTMCS was lower than that of unmodified CS. The antibacterial activities of OFTMCS were investigated by assessing the mortality rates of the representative Gram‐positive and Gram‐negative bacteria Staphylococcus aureus and Escherichia coli, respectively. The results indicated that OFTMCS exhibited superior antibacterial activity to CS at a lower dosage. The synthesis of CS derivatives bearing dual‐functional groups could therefore be used as a promising strategy to enhance the antibacterial activity of CS. The antimicrobial mechanism of action of OFTMCS was discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42663.     

Stability of a chitosan layer deposited onto a polyethylene surface

A two‐step procedure was applied to obtain antimicrobial films; this procedure involved a corona treatment of the polyethylene (PE) surface and its chemical activation with 1‐ethyl‐3‐[3‐dimethylaminopropyl] carbodiimide hydrochloride and N‐hydroxysuccinimide, and this led to the covalent bonding of chitosan on the PE surface. Electrochemical methods were used to investigate the stability of the deposited chitosan layer. The potentiometric and polyelectrolyte titrations showed that some amount of chitosan desorbed faster from the surface until equilibrium was reached and also that the grafted chitosan layer was more stable than the physically adsorbed one. The chitosan immobilized on the PE surface exhibited the expected antibacterial activity when tested against three bacteria, which included two Gram‐negative bacteria, Salmonella enteritidis and Escherichia coli, and one Gram‐positive bacterium, Listeria monocytogenes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2444–2457, 2013     

Removal of Cr(VI) from aqueous solution using amino‐modified Fe3O4–SiO2–chitosan magnetic microspheres with high acid resistance and adsorption capacity

A novel, bioadsorbent material of polyethylenimine‐modified magnetic chitosan microspheres enwrapping magnetic silica nanoparticles (Fe₃O₄–SiO₂–CTS‐PEI) was prepared under relatively mild conditions. The characterization results indicated that the adsorbent exhibited high acid resistance and magnetic responsiveness. The Fe₃O₄ loss of the adsorbent was measured as 0.09% after immersion in pH 2.0 water for 24 h, and the saturated magnetization was 11.7 emu/g. The introduction of PEI obviously improved the adsorption capacity of Cr(VI) onto the adsorbent by approximately 2.5 times. The adsorption isotherms and kinetics preferably fit the Langmuir model and the pseudo‐second‐order model. The maximum adsorption capacity was determined as 236.4 mg/g at 25°C, which was much improved compared to other magnetic chitosan materials, and the equilibrium was reached within 60 to 120 min. The obtained thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption process. Furthermore, the Cr(VI)‐adsorbed adsorbent could be effectively regenerated using a 0.1 mol/L NaOH solution, and the adsorbent showed a good reusability. Due to the properties of good acid resistance, strong magnetic responsiveness, high adsorption capacity, and relatively rapid adsorption rate, the Fe₃O₄–SiO₂–CTS‐PEI microspheres have a potential use in Cr(VI) removal from acidic wastewater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43078.     

Synthesis and antimicrobial activities of new water‐soluble bis‐quaternary ammonium methacrylate polymers

New methacrylate monomers containing pendant quaternary ammonium moieties based on 1,4‐diazabicyclo‐[2.2.2]‐octane (DABCO) were synthesized. The DABCO group contains either a butyl or a hexyl pendant group comprising the hydrophobic segment of the monomers and one tether group to the methacrylate moiety. The monomers were homopolymerized in water by using 2,2′‐azobis(2‐methylpropionamide) dihydrochloride (V‐50) as an initiator. The monomers and polymers were characterized by elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), FTIR, and ¹³C‐NMR. The antimicrobial activities of the corresponding small molecules (bis‐quaternary ammonium monocarboxylates) and polymers were investigated against Staphylococcus aureus and Escherichia coli. Although the small molecules did not show any antimicrobial activity, the polymers were moderately effective against both Gram‐positive and Gram‐negative bacteria. The minimum inhibitory concentration (MIC) values of the polymers with butyl and hexyl hydrocarbon chains against S. aureus and E. coli were found to be 250 and 62.5 μg/mL, respectively. The minimum bactericidal concentration (MBC) value for the polymer with the butyl group was higher than 1 mg/mL, whereas the MBC value for the polymer with hexyl group was found to be 62.5 μg/mL. Thus, an increase of the alkyl chain length from 4 to 6 significantly increased the antimicrobial activity of the polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 635–642, 2004     

Semitransparent chitosan‐TiO2 nanotubes composite film for food package applications

Semitransparent composite films were prepared made from TiO₂ nanotubes in chitosan (CS) matrix. Hydrothermally synthesized titanium nanotubes (TiNTs) were dispersed in chitosan matrix in order to produce film‐forming solutions at 0.05 and 0.10% w/v. Structural, topological, optical and thermal properties of these films were evaluated. The antimicrobial activity of films against Salmonella enterica serovar Typhimurium, Escherichia coli (Gram‐negatives) and Staphylococcus aureus (Gram‐positive) was also investigated. Fourier transform infrared (FTIR) spectra showed effective site‐selective interactions between chitosan and TiNTs. TiNTs prevented the degradation of films, avoiding the oxidization of the glucosamine ring. Characterizing techniques such as, Scanning electron microscopy–energy dispersive spectroscopy (SEM‐EDS) line profile and atomic force microscopy (AFM) were used to examine the TiNTs dispersion within the film. The morphological analysis indicated that the TiNTs were well dispersed and became clustered proportionally to the weight percentage of TiNTs used in the composites. The UV‐Vis spectra showed that TiNTs increased the film absorption in the UV region and the light barrier properties of films remained stable over the storage period. Photoacoustic spectroscopy (PAS) was used to study these films, nondestructively for their thermal effusivity (e). The films were effective in reducing the microbial concentration in the liquid culture for all bacteria tested. The effectiveness was found to dependent on the bacterial strain and TiNTs content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and Characterization of Cationic Surfactants Based on N‐Hexamethylenetetramine as Active Microfouling Agents

Four cationic surfactants of quaternary hexammonium silane chloride based on hexamethylenetetramine and alkyl chloride were synthesized. The chemical structures of the prepared cationic surfactants were elucidated using Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry analysis. The surface and thermodynamic properties of the prepared surfactants were also studied. The performance of these cationic surfactants as microfouling agents against two strains of Gram‐negative bacteria, namely, Pseudomonas aeruginosa and Escherichia coli, and two strains of Gram‐positive bacteria, namely, Staphylococcus aureus and Bacillus subtilis, were evaluated as antimicrobial agents. The results showed that the maximum antimicrobial activity was detected for N‐hexamethylenetetramine‐N‐ethyl silane ammonium trichloride (Ah). The maximum and minimum antimicrobial activities were 73 and 60 % against S. aureus and E. coli, respectively, at a concentration of 5 mg/l, pH 7, and 37 °C.     

Manufacture and properties of chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers

Chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers (CNVFs) were prepared by blending chitosan emulsion, N,O‐carboxymethylated chitosan (N,O‐CMC), and viscose rayon together for spinning. The fibers were characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). TEM micrographs showed that chitosan microparticles dispersed uniformly along the oriented direction with the mean size ranging from 0.1 to 0.5 μm. DSC spectra of these fibers showed that no significant change in thermal property was caused by adding chitosan and N,O‐CMC into the viscose rayon. TGA spectra showed that the good moisture retentivity was not affected by the addition of chitosan and N,O‐CMC. Both DSC and TGA suggested that the decomposing tendency of the viscose rayon above 250°C seemed to be weakened by the chitosan. The fibers' mechanical properties and antibacterial activities against Escherchia coli, Staphylococcus aureus, and Candida albicans were measured. Although the addition of chitosan slightly reduced the mechanical properties, the antibacterial fibers' properties were obtained and were found to meet commercial requirements. CNVF exhibited excellent antibacterial activity against E. coli, S. aureus, and C. albicans. The antibacterial activity increased along with the chitosan concentration and was not greatly affected by 15 washings in water. Scanning electron microscopy (SEM) was used to observe the morphology of bacteria cells incubated together with the antibacterial or reference fibers. SEM micrographs demonstrated that greater amounts of bacteria could be adsorbed by the antibacterial fiber than by the reference fiber; these bacteria were overwhelmingly destroyed and killed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2049–2059, 2002; DOI 10.1002/app.10501     

Synthesis of PEGylated chitosan copolymers as efficiently antimicrobial coatings for leather

In this work, poly(ethylene glcycol)‐grafted chitosan (PEG‐g‐CS) was synthesized by conjugating PEG to the chitosan (CS) backbone. Such PEGylated CS copolymer was further characterized by FTIR and ¹H NMR, and the results demonstrated the successful synthesis. After PEGylation, the water solubility of CS was significantly improved due to the hydrophilicity of the PEG polymer. Therefore, this PEGylated CS was prepared as water borne coating for leather surface. The morphology and hydrophilicity of this coating on leather was studied by SEM and water contact angle measurement. Furthermore, the antimicrobial activity of PEGylated CS coating was investigated by measuring its minimum inhibitory concentration and the inhibition zone of coated leather against Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus, respectively. Compared to CS coating, such PEG‐g‐CS coating exhibited better antimicrobial property, which indicated the synergetic effect of the antimicrobial property of CS and the antiadhesive property of PEG. Thus, this PEGylated CS copolymer can be used as efficiently antimicrobial coating for leather product. © 2016 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43465.