Synthesis and antimicrobial activity of Schiff base of chitosan and acylated chitosan

Chitosan, a biocompatible, biodegradable, nontoxic polymer, is prepared from chitin, which is the second most naturally occurring biopolymer after cellulose. Schiff base of chitosan, sorbyl chitosan, and p‐aminobenzoyl chitosan were synthesized working under high‐intensity ultrasound and their antimicrobial properties were analyzed against Escherichia coli, Staphylococcus aureus, and Aspergillus niger. The structures of the derivatives were characterized by FTIR spectroscopy and elemental analysis. The results of antimicrobial activities indicated that the antimicrobial activities of the derivatives increased with increasing the concentration. The antibacterial activity of schiff base of chitosan against E. coli was stronger, while acylated chitosan had better inhiting effect on S. aureus than others. It was also found that the antifungal activities of the derivatives were stronger than that of chitosan, and schiff base of chitosan was obviously superior to acylated chitosan. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Chitosan Schiff base as eco-friendly inhibitor for mild steel corrosion in 1 M HCl

In the present study, natural biopolymer chitosan was modified into its Schiff base derivative with salicylaldehyde by condensation method. The prepared chitosan salicylaldehyde Schiff base was characterized using ultraviolet spectroscopy, fourier transform infrared spectroscopy, scanning electron microscope and elemental analysis. Thermal analysis was also carried out to determine the thermal stability of the derivative. To explore the corrosion inhibition performance of the chitosan Schiff base, weight loss, and electrochemical techniques were conducted. The inhibitor reduces the metallic corrosion by adsorbing on to the metal surface. The adsorption of chitosan Schiff base on mild steel surface in 1 M HCl follows Temkin isotherm model. Thermodynamic parameters of adsorption and corrosion process were calculated, which revealed the chemical nature of adsorption. SEM and energy dispersive X-ray spectroscopic analysis confirmed the formation of protective chitosan derivative layer on the mild steel surface.     

Preparation and antibacterial activity of C2-benzaldehyde-C6-aniline double Schiff base derivatives of chitosan

C₂-benzaldehyde-C₆-aniline double Schiff base derivatives of chitosan were synthesized with positioning protection method for the first time. The structures and properties of the new synthesized products were characterized by Fourier transform infrared spectroscopy, ¹³C nuclear magnetic resonance, scanning electron microscope image, X-ray diffraction, and elemental analysis. The elemental analysis results indicated that the degrees of substitution of the products were from 39.6% to 48.2%. The synthesized compounds exhibited an excellent solubility in organic solvents. The antibacterial activities of all of the derivatives were tested in the experiment, and the results showed that the prepared chitosan derivatives had significantly improved antibacterial activity of chitosan and C₂-benzaldehyde Schiff bases of chitosan toward Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 35218). Antibacterial activity of the Schiff bases against E. coli differs from the substituent at the same position of different anilines and increases as the sequence aniline?>?p-toluidine?>?o-toluidine, and the antibacterial activity of the Schiff bases against S. aureus increases as the sequence p-toluidine?>?aniline?>?o-toluidine. The I_C50 of the C₂-benzaldehyde-C₆-aniline double Schiff base derivatives of chitosan against E. coli and S. aureus is 0.0035 and 0.0031?mg?L^?1, respectively, much lower than that of chitosan (0.0064?mg?L^?1) and C₂-benzaldehyde Schiff bases of chitosan (0.0054?mg?L^?1). The cytotoxicity test showed that compared with chitosan and C₂-benzaldehyde Schiff bases of chitosan, the prepared chitosan derivatives had lower cytotoxicity against SCG-7901. This paper provided a new method for the synthesis of Schiff bases of chitosan, which was enlightening.     

Preparation,characterization, and optical properties of a chitosan–anthraldehyde crosslinkable film

A novel chitosan–anthraldehyde derivative film was prepared by the reaction of 79% deacetylated chitosan with 9‐anthraldehyde with a hydrogel by a solution casting method. The prepared chitosan derivative film was confirmed by ultraviolet–visible absorption spectroscopy of the absorption peak at 266 nm due to the presence of an anthracene ring. The crosslinking reaction showed significant changes in the Fourier transform infrared spectrum of the chitosan derivative film. The characteristic peak of CH?N stretching bands at 1610 cm^?1 confirmed the formation of a Schiff base after the reaction of chitosan with 9‐anthraldehyde. The film was evaluated by X‐ray diffraction, scanning electron microscopy, photoluminescence spectroscopy, and second harmonic generation (SHG). The nature of the crystallinity of the chitosan derivative from X‐ray diffraction analysis confirmed that the film may have had nonlinear optical properties. The chitosan derivative showed a redshifted emission maximum because of the electron‐rich polymer main chain. No reabsorption of the second harmonic signal and no resonance enhancements were noticed during the SHG study; this indicated that the chitosan derivative possessed SHG ability. Overall, the chitosan derivative film opens new perspectives for optical material for biomedical applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study of the synthesis of chitosan derivatives containing benzo‐21‐crown‐7 and their adsorption properties for metal ions

Three new chitosan crown ethers, N‐Schiff base‐type chitosan crown ethers (I, III), and N‐secondary amino type chitosan crown ether (II) were prepared. N‐Schiff base‐type chitosan crown ethers (I, III) were synthesized by the reaction of 4′‐formylbenzo‐21‐crown‐7 with chitosan or crosslinked chitosan. N‐Secondary amino type chitosan‐crown ether (II) was prepared through the reaction of N‐Schiff base type chitosan crown ether (I) with sodium brohydride. Their structures were characterized by elemental analysis, infrared spectra analysis, X‐ray diffraction analysis, and solid‐state ¹³C NMR analysis. In the infrared spectra, characteristic peaks of C?N stretch vibration appeared at 1636 cm^?1 for I and 1652 cm^?1 for II; characteristic peaks of N? H stretch vibration appeared at 1570 cm^?1 in II. The X‐ray diffraction analysis showed that the peaks at 2θ = 10° and 28° disappeared in chitosan derivatives I and III, respectively; the peak at 2θ = 10° disappeared and the peak at 2θ = 28° decreased in chitosan‐crown ether II; and the peak at 2θ = 20° decreased in all chitosan derivatives. In the solid‐state ¹³C NMR, characteristic aromatic carbon appeared at 129 ppm in all chitosan derivatives, and the characteristic peaks of carbon in C?N groups appeared at 151 ppm in chitosan crown ethers I and III. The adsorption and selectivity properties of I, II, and III for Pd²⁺, Au³⁺, Pt⁴⁺, Ag⁺, Cu²⁺, and Hg²⁺ were studied. Experimental results showed these adsorbents not only had good adsorption capacities for noble metal ions Pd²⁺, Au³⁺, Pt⁴⁺, and Ag⁺, but also high selectivity for the adsorption of Pd²⁺ with the coexistence of Cu²⁺ and Hg²⁺. Chitosan‐crown ether II only adsorbs Hg²⁺ and does not adsorbs Cu²⁺ in an aqueous system containing Pd²⁺, Cu²⁺, and Hg²⁺. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1886–1891, 2002     

Synthesis,characterization, and drug‐release behavior of amphiphilic quaternary ammonium chitosan derivatives

A new type of amphiphilic quaternary ammonium chitosan derivative, 2‐N‐carboxymethyl‐6‐O‐diethylaminoethyl chitosan (DEAE–CMC), was synthesized through a two‐step Schiff base reaction process and applied to drug delivery. In the first step, benzaldehyde was used as a protective agent for the incorporation of diethylaminoethyl groups to form the intermediate (6‐O‐diethylaminoethyl chitosan). On the other hand, NaBH₄ was used as a reducing agent to reduce the Schiff base, which was generated by glyoxylic acid, for the further incorporation of carboxymethyl groups to produce DEAE–CMC. The structure, thermal properties, surface morphology, and diameter distribution of the resulting chitosan graft copolymers were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, X‐ray powder diffraction, scanning electron microscopy, and laser particle size analysis. Benefiting from the amphiphilic structure, DEAE–CMC was able to be formed into microspheres in aqueous solution with an average diameter of 4.52 ± 1.21 μm. An in vitro evaluation of these microspheres demonstrated their efficient controlled release behavior of a drug. The accumulated release ratio of vitamin B₁₂ loaded DEAE–CMC microspheres were up to 93%, and the duration was up to 15 h. The grafted polymers of DEAE–CMC were found to be blood‐compatible, and no cytotoxic effect was shown in human SiHa cells in an MTT [3‐(4, 5‐dimethyl‐thiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] cytotoxicity assay. These results indicate that the DEAE–CMC microspheres could be used as safe, promising drug‐delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39890.     

壳聚糖希夫碱及壳聚糖改性微球的吸附性能研究

以壳聚糖和对二甲氨基苯甲醛为原料合成壳聚糖希夫碱,以壳聚糖希夫碱为底物,采用反相悬浮聚合法,制备壳聚糖希夫碱微球。对二者的吸附性能进行比较研究。结果表明,希夫碱微球的吸附性能优于壳聚糖希夫碱,对四氧化三铁的吸附容量分别为113.179 mg/g和39.279 mg/g,对亚甲基蓝的吸附平衡时间均为150 min,饱和吸附容量随着亚甲基蓝初始质量浓度的增大而增大,且微球的吸附容量大于壳聚糖希夫碱,吸附率不随浓度增大单调递增,而是有一极大值。     

Dielectric,magnetic, and mechanical properties of composites consisting of biopolymer chitosan matrix and hybrid spinel/cellulose filler

The composites consisting of a biopolymer chitosan matrix and hybrid spinel/cellulose filler were prepared by solvent casting method whereas the spinel CoFe₂O₄ was obtained by mechanical synthesis followed by thermal annealing. Incorporation of cellulose to the spinel – chitosan composite significantly modified dielectric, magnetic and mechanical properties of a composite consisting of the biopolymer with hybrid filler. In dielectric response the presence of the filler in the chitosan matrix hindered the molecular motion. The lowering of the activation energy and the cooperativity of the motion was observed. According to the magnetic properties, addition of cellulose to the filler enhanced coercivity field H_c in comparison to the pure spinel powder from value 0.1453 to 0.2033?T. In mechanical properties incorporation of the filler resulted in improvement of Young's modulus and tensile strength in comparison to unfilled chitosan. For composites with nanocellulose filler tensile strength was over two times higher than for chitosan.     

Synthesis,characterization and properties of cellulose‐grafted glycine derivatives

Novel Schiff base cellulose derivatives were successfully prepared by a bridge‐coupling reaction from dialdehyde cellulose (DAC), which was obtained by the selective oxidation of sodium periodate to cotton fibers, in which the glycine (Gly) was bonded onto the DAC chains by a Schiff base reaction with p‐nitrobenzaldehyde as a bridge. The structures of the graft copolymer (DAC‐g‐Gly) were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, solid‐state NMR, and scanning electronic microscopy. The thermodynamic properties were analyzed by thermogravimetric analysis and differential scanning calorimetry, and the biodegradability was also tested by the microbial degradation and the active sludge method. The results indicate that Gly was connected to DAC by chemical bonding, which changed the thermal stability, and that DAC‐g‐Gly could be biodegraded significantly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40929.     

羧甲基壳聚糖席夫碱的制备及抗菌性能研究

在超声波作用下,以自制的低分子量羧甲基壳聚糖与香草醛为原料,制备了低分子量羧甲基壳聚糖香草醛席夫碱。利用FI-IR对其结构进行了表征,研究了香草醛与羧甲基壳聚糖中氨基的反应摩尔比、反应温度、反应时间及超声波功率对产物氨基取代度的影响。结果表明：当香草醛与羧甲基壳聚糖中氨基的摩尔比为1∶0.8、反应时间为3 h、反应温度为70℃、超声波作用功率为70 W时,羧甲基壳聚糖香草醛席夫碱的氨基取代度可达到82.5%;将羧甲基壳聚糖席夫碱与羧甲基壳聚糖的抗菌性能进行了比较,发现羧甲基壳聚糖香草醛席夫碱对金黄葡萄球菌和大肠埃希菌的抑菌圈宽度分别比羧甲基壳聚糖的抑菌圈宽0.7 mm和0.5 mm。     

The ring‐opening polymerization of D,L‐lactide catalyzed by new complexes of Cu,Zn, Co,and Ni Schiff base derived from salicylidene and L‐aspartic acid

D ,L ‐lactide (LA) was first successfully ring‐opening polymerized in melt by Schiff base complexes K[ML]nH₂O [M = Cu(II), Zn(II), Co(II), Ni(II); n = 2, 2, 3, 3.5; H₃L = L‐aspartic acid‐salicylidene Schiff base], which were prepared by Schiff base ligand derived from salicylidene and L‐aspartic acid and corresponding acetates. The effects of various complexes, the molar ratio of K[ML]nH₂O/LA, the polymerization temperature, and time were studied in detail. The results show that all complexes studied have the ability to initiate the ring‐opening polymerization of D ,L ‐lactide in melt. More than 90% high polymerization conversion and narrow molecular weight distribution (MWD) can be obtained very easily. However, the Ni(II) complex shows better catalytic property than other complexes on the polymerization and the molecular weight (MW) of poly(D ,L ‐lactide) (PLA) produced. With a rise in temperature and a prolongation of time, the MW of PLA decreased remarkably. The MW of PLA prepared by all complexes is not very high, which might be related to the crystalline water of complexes. X‐ray study indicated that PLA produced by Ni(II) complex is an amorphous polymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3312–3315, 2002     

Studies on the synthesis and properties of hydroxyl azacrown ether‐grafted chitosan

The chitosan hydroxyl azacrown ether was synthesized by reaction of hydroxyl azacrown ether with epoxy‐activated chitosan. The C₂ amino group in chitosan was protected from the reaction between benzaldehyde and chitosan to form N‐benzylidene chitosan. After reaction with epichlorohydrin and azacrown ether, reacting O‐aryl mesocyclic diamine‐N‐benzylidene chitosan and dilute ethanol hydrochloride solution to obtain novel chitosan‐azacrown ether bearing hydroxyl removed the Schiff base. Its structure was confirmed with elemental analysis, FTIR spectra analysis, X‐ray diffraction analysis, and solid‐state ¹³C NMR analysis. Its static adsorption properties for Ag(I), Cd(II), Pb(II), and Cr(III) were also investigated. The experimental results showed that the hydroxyl azacrown ether grafted chitosan has good adsorption capacity and high selectivity for Ag(I) in the coexistence of Pb(II) and Cd(II), the selectivity coefficients of hydroxyl azacrown ether chitosan were K_Ag(I)/Pb(II) = 32.34; K_Ag(I)/Cd(II) = 56.12. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1838–1843, 2001     

Physiochemical, optical and biological activity of chitosan-chromone derivative for biomedical applications

This paper describes the physiochemical, optical and biological activity of chitosan-chromone derivative. The chitosan-chromone derivative gels were prepared by reacting chitosan with chromone-3-carbaldehyde, followed by solvent exchange, filtration and drying by evaporation. The identity of Schiff base was confirmed by UV-Vis absorption spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. The chitosan-chromone derivative was evaluated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), photoluminescence (PL) and circular dichroism (CD). The CD spectrum showed the chitosan-chromone derivative had a secondary helical structure. Microbiological screening results demonstrated the chitosan-chromone derivative had antimicrobial activity against Escherichia coli bacteria. The chitosan-chromone derivative did not have any adverse effect on the cellular proliferation of mouse embryonic fibroblasts (MEF) and did not lead to cellular toxicity in MEFs. These results suggest that the chitosan-chromone derivative gels may open a new perspective in biomedical applications.     

Effects of Acylation and Crosslinking on the Material Properties and Cadmium Ion Adsorption Capacity of Porous Chitosan Beads

Abstract

Chitosan is a novel glucosamine biopolymer derived from the shells of marine organisms. This biopolymer is very attractive for heavy metal ion separations from wastewater because it is selective for toxic transition metal ions over less toxic alkali or alkane earth metal ions. Highly porous, 3-mm chitosan beads were prepared by an aqueous phase-inversion technique for casting gel beads followed by freeze drying. In the attempt to simultaneously improve material properties and adsorption capacity, chitosan was chemically modified by 1) homogeneous acylation of amine groups with nonanoyl chloride before bead casting, and 2) heterogeneous crosslinking of linear chitosan chains with the bifunctional reagent glutaric dialdehyde (GA) after bead casting but before freeze drying. The random addition of C₈ hydrocarbon side chains to about 7% of the amine groups on uncrosslinked chitosan beads via N-acylation improved the saturation adsorption capacity from 169 to 216 mg Cd²⁺/g-bead at saturation (pH 6.5, 25°C) but only slightly reduced solubility in acid solution. Crosslinking of the N-acylated chitosan beads with 0.125 to 2.5 wt% GA in the crosslinking bath increased the internal surface area from 40 to 224 m²/g and rendered the beads insoluble in 1 M acetic acid (pH 2.36). However, crosslinking of the N-acylated chitosan beads reduced the saturation adsorption capacity to 136 mg Cd²⁺/g-bead at 0.75 wt% GA and 86 mg Cd²⁺/g-bead at 2.5 wt% GA. Crosslinking also significantly reduced the compression strength. There was no clear relationship between internal surface area and adsorption capacity, suggesting that the adsorbed cadmium was not uniformly loaded into the bead.     

Chitosan Schiff base as effective corrosion inhibitor for mild steel in acid medium

An environment friendly inhibitor, chitosan thiophene carboxaldehyde Schiff base, was synthesized by a condensation reaction of the carbonyl group of thiophene 2‐carboxaldehyde and free amino groups of chitosan. The chitosan Schiff base was characterized by UV spectroscopy, Fourier transform IR spectroscopy, elemental analysis and thermal analysis. The surface morphology of the Schiff base derivative was examined by SEM. Gravimetric and electrochemical techniques were used to explore the behaviour of the chitosan thiophene derivative as a corrosion inhibitor for mild steel in an acidic environment. The effects of inhibitor concentration, exposure time and temperature were investigated. The chitosan Schiff base showed a good inhibition performance of 92% inhibition efficiency at room temperature for 12 h of immersion in a weight loss experiment. The electrochemical results showed that the chitosan derivative acts as an effective mixed type inhibitor. The adsorption of the inhibitor followed the Temkin isotherm model. SEM and AFM techniques were used to characterize the protective layer formed on the mild steel substrate. © 2016 Society of Chemical Industry     

Synthesis,conductivity, and electromagnetic wave absorption properties of chiral poly Schiff bases and their silver complexes

Four chiral poly Schiff bases were synthesized via polycondensation between l‐ lysine and p‐benzoquinone, 1,4‐naphthoquinone, dibenzoyl, and 2,3‐butanedione, respectively. Subsequently, the silver coordination polymers of the chiral poly Schiff base were prepared upon silver ions coordinating with the chiral poly Schiff bases. The structures of the polymers were characterized with IR, UV‐vis, GPC, elemental analysis, and optical activity analysis. The properties of polymers were studied through conductivity testing and electromagnetic parameter testing. The results show that they own good electrical conductvities, and the electrical conductivity of chiral poly‐(l‐ lysine(2,3‐butanedione)) Schiff base silver complex can reach 3.7 × 10² S/cm. The electromagnetic wave absorption properties of four silver complexes were calculated using transmission line theory, the maximum reflection loss of chiral poly‐(l‐ lysine(p‐benzoquinone)) Schiff base silver complex can reach ?45.9 dB at a thickness of 5 mm, while that of achiral poly‐(dl ‐lysine(p‐benzoquinone)) Schiff base silver complex is ?20.1 dB at a thickness of 5 mm. The enhanced microwave absorbing properties were attributed to the chiral feature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42498.     

Synthesis and characterization of new arylamine chitosan derivatives

The synthesis of new chitosan derivatives and their complete characterization by elemental analysis, Fourier transform infrared, thermogravimetric analysis, and cross‐polarity/magic‐angle‐spinning ¹³C NMR is described. A chitosan that was 96.5% deacetylated and had a viscosimetric molecular weight of 131,000 g/mol was prepared. N‐(3,5‐Diethylaminobenzoyl) chitosan with a degree of substitution of 29% and N‐(4‐ethylaminobenzoyl) chitosan with a degree of substitution of 60% were obtained. Such derivatives could be used as metal‐chelating polymers, as flocculants, and in biomedical applications because of the aryl amine moieties in their structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 807–812, 2004     

Preparation and antibacterial activity of Schiff bases from O-carboxymethyl chitosan and para-substituted benzaldehydes

Seven Schiff bases were synthesized from O-carboxymethyl chitosan (CMC) and para-substituted benzaldehydes. The Schiff bases were characterized through Fourier Transform Infrared Spectroscopy, Carbon-13 Nuclear Magnetic Resonance (¹³C NMR), Distortionless Enhancement of Polarization Transfer (DEPT) 135 NMR, elemental analysis, and acid–base titration. Antibacterial activities of the Schiff bases against Escherichia coli (E. coli, ATCC 35218) and Staphylococcus aureus (S. aureus, ATCC 25923) were measured through the optical density method. Antibacterial activity of the Schiff bases differs from the substituent at the para position of benzaldehyde, and decreases as the sequence OCH₃ > CH₃ > H > F > Cl > Br > NO₂. The IC₅₀ of the Schiff base from 4-methoxylbenzylaldehyde against E. coli and S. aureus is 30 and 34 ppm, respectively, much lower than that of chitosan (53, 48 ppm) and CMC (58, 60 ppm).     

5-溴水杨醛改性壳聚糖的制备及吸附性能

制备了两种不同形态的改性壳聚糖希夫碱：微粒化的壳聚糖希夫碱（P-CTSS），未微粒化的壳聚糖希夫碱（CTSS），并研究了它们分别对Cu^2＋，Pb^2＋，Cd^2＋及Zn^2＋的吸附性能，考察了pH值、时间等因素对吸附性能的影响。结果表明，P-CTSS较CTSS易于粉碎，且吸附性能较好。CTSS对Cu^2＋，Pb^2＋，Cd^2＋及Zn^2＋的吸附容量分别为：15．21、10．35、12．13、9．28mg／g，而P-CTS对Cu^2＋，Pb^2＋，Cd^2＋及Zn^2＋的吸附容量分别为：37．46、15．84、16．34、13．67mg／g，P-CTSS对Cu^2＋的吸附率在2．5h内达到84．5％左右，具有一定的选择性吸附。     

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.