Facile preparation and potential application of water‐soluble polymeric temperature/pH probes bearing fluorescein

An unsaturated monomer bearing xanthene groups and allyloxyfluorescein (Al‐Flu), was synthesized from fluorescein and allyl bromide by etherification. The structure of the monomer was confirmed by IR and mass spectroscopy and ¹H‐NMR, and ¹³C‐NMR spectroscopy. With azobisisobutyronitrile as a thermal initiator in tetrahydrofuran under 65–70°C, a copolymer of allyloxyfluorescein and acrylamide [poly(Al‐Flu‐co‐AM)] was obtained and was characterized by the methods of IR spectroscopy, ultraviolet–visible spectroscopy, and differential scanning calorimetry. The experimental results show that the fluorescence spectra of water‐soluble poly(Al‐Flu‐co‐AM) was dependent on the pH and temperature in the solution. Moreover, poly(Al‐Flu‐co‐AM) had an excellent linear response between the relative fluorescence intensity and temperature in the range 0–60°C and had a nonlinear response from pH 0.00 to 12.85 between the relative fluorescence intensity and pH. The pH and temperature sensitivities of the fluorescence could be advantageous for it as a multifunctional material to probe pH and temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Preparation and antimicrobial activity of sulfopropyl chitosan in an ionic liquid aqueous solution

To improve the solubility and antibacterial activity of chitosan and expand its applications, we synthesized sulfopropyl chitosan (SP‐CS) with various degrees of substitution (DSs) under mild and green reaction conditions in the aqueous solution of an ionic liquid by a green process. The chemical structures of the polymers were verified by Fourier transform infrared spectroscopy and ¹H‐NMR, and the thermal stability was studied by thermogravimetric analysis. After modification, the water solubility of chitosan was improved significantly, and SP‐CS showed excellent solubility in water at neutral pH. The antibacterial activities of the SP‐CSs with various DSs were systematically studied for the first time by the Oxford cup method and optical density method. The results suggest that the antimicrobial properties of SP‐CS were enhanced by the introduction of sulfopropyl and increased with increasing DS. The application of chitosan could be expanded, and SP‐CS has the potential to be used as a water‐soluble antimicrobial. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44989.     

Preparation and properties of sulfopropyl chitosan derivatives with various sulfonation degree

In this investigation, chitosan (CS) is modified by propane sultone via a sulfonation reaction to create various degrees of sulfonation. The sulfonated chitosan (SCS) has a pendant alkyl sulfonic group dangling at the side chain, which can improve its hydrophilicity and water solubility. Elemental analysis, Fourier transform infrared spectroscopy (FTIR) and ¹³C nuclear magnetic resonance (¹³C NMR) were applied to identify the structure by determining the distribution of the substituents in the product. The degree of sulfonation in the SCS can be controlled and the hydrogen bonding interaction can be reduced by varying the degree of sulfonation. A solubility test proved that solubility increased with degree of substitution at over a wide range of pH values. X‐ray diffraction patterns of SCS samples demonstrated that the crystallinity declined as the degree of sulfonation increased. Thermogravimetric analysis and modulated differential scanning calorimetry (MDSC) results indicated that thermal stability fell but water absorbance increased with the degree of sulfonation. More water‐soluble SCS is thus obtained. The controllable different sulfonation degree of the CS polymer suggests new possibilities for the application of CS‐based materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of ion‐imprinting chitosan/PVA crosslinked membrane for selective removal of Ag(I)

A novel ion‐imprinted membranes were synthesized for selective removal and preconentration for Ag(I) ions from aqueous solutions. The membranes were obtained via crosslinking of chitosan (CS), PVA, and blend chitosan/PVA using glutaraldehyde (GA) as crosslinker. The FTIR spectra were used to confirm the membrane formation. Comparing with the nonimprinted membranes, Ag(I)‐imprinted CS and CS/PVA has higher removal capacity and selectivity for Ag⁺ ions. An enhancement in the Ag⁺ removal capacity by ～ 20% (from 77.8 to 94.4 mg g^–1) and ～ 50% (from 83.9 to 125 mg g^–1) was found in the Ag(I)‐imprinted CS and Ag(I)‐imprinted CS/PVA membranes, respectively, when compared with the nonimprinted membranes. Removal equilibra was achieved in about 40 min for the non‐ and ion‐imprinted CS/PVA. The pH and temperature significantly affected the removal capacity of ion‐imprinted membrane. The relative selectivity coefficient values of Ag⁺/Cu²⁺ and Ag⁺/Ni²⁺ are 9 and 10.7 for ion‐imprinted CS membrane and 11.1 and 15 for ion‐imprinted CS/PVA membrane when compared with nonimprinted membranes. The imprinted membranes can be easily regenerated by 0.01M EDTA and therefore can be reused at least five times with only 15% loss of removal capacity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Aqueous Solution‐Processable,Flexible Thin‐Film Transistors Based on Crosslinked Chitosan Dielectric Thin Films

The hydrophilic character of chitosan (CS) limits its use as a gate dielectric material in thin‐film transistors (TFTs) based on aqueous solution‐processable semiconductor materials. In this study, this drawback is overcome through controlled crosslinking of CS and report, for the first time, its application to aqueous solution‐processable TFTs. In comparison to natural CS thin films, crosslinked chitosan (Cr‐CS) thin films are hydrophobic. The dielectric properties of Cr‐CS thin films are explored through fabrication of metal–insulator–metal devices on a flexible substrate. Compared to natural CS, the Cr‐CS dielectric thin films show enhanced environmental and water stabilities, with a high breakdown voltage (10 V) and low leakage current (0.02 nA). The compatibility of Cr‐CS dielectric thin films with aqueous solution‐processable semiconductors is demonstrated by growing ZnO nanorods via a hydrothermal method to fabricate flexible TFT devices. The ZnO nanorod‐based TFTs show a high field‐effect mobility (linear regime) of 10.48 cm² V^?1 s^?1. Low temperature processing conditions (below 100 °C) and water as the solvent are utilized to ensure the process is environmental friendly to address the e‐waste problem.     

Preparation of O‐carboxymethyl‐N‐trimethyl chitosan chloride and flocculation of the wastewater in sugar refinery

A novel water soluble amphiphilic O‐ carboxymethyl‐N‐trimethyl Chitosan chloride (CMTMC) was synthesized. The structure of this material was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C nuclear magnetic resonance (¹³C‐NMR) spectroscopy and X‐ray diffraction (XRD) techniques. The results showed that CMTMC had been successfully prepared. To determine the flocculation performance of the synthesized amphiphilic polymer, a comparison was made among Chitosan (CS), N‐trimethyl chitosan chloride (TMC), O‐carboxymethyl chitosan (CMC), and CMTMC on the turbidity and COD removal efficiency of 1% (v/v) wastewater in sugar refinery suspensions at pH 5.0, 7.0 and 9.0 at a dosage range of 0–8 mg/L. The results showed that the water soluble amphiphilic polymer CMTMC, which contains longer polymer anion and polymer cation, had the best performance not only in turbidity removal but also in COD removal on sugar refinery wastewater. The using of CMTMC as a flocculant to treat wastewater in sugar refinery was actually more effective than CS, CMC, and TMC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and evaluation of chitosan‐vitamin C complexes

Chitosan (CS) is a biocompatible, biodegradable, and nontoxic polysaccharide polymer. It dissolves in water only if the pH is lower than 6.5. To extend its range of application, many water‐soluble derivatives have, therefore, been prepared. In this research, chitosan‐vitamin C complexes (CSVC) were synthesized and characterized with FTIR, DSC, and ¹H‐NMR. The solubility of CSVC in distilled water was greatly improved. The ?O₂^‐ scavenging activity of CSVC was compared with CS and vitamin C (VC) by measuring the auto‐oxidation rate of pyrogallic acid. Results showed that the scavenging activity on ?O₂^? by CSVC was stronger than that by CS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of modified oligochitosan and evaluation of its scale inhibition and fluorescence properties

To obtain an environmentally friendly and efficient scale inhibitor, carboxymethyl quaternary ammonium oligochitosan (CM‐QAOC) was prepared from chitosan, which was depolymerized by nitrous acid, and then reacted with chloroacetic acid and glycidyl trimethyl ammonium chloride via carboxymethylation and quaternization, respectively. The chitosan derivatives were characterized by Fourier transform infrared and NMR spectroscopy. The inhibition performance for CM‐QAOC was evaluated by a conductivity method and a static antiscaling test. The experiments demonstrated that CM‐QAOC showed an excellent scale‐inhibition performance. With a Ca²⁺ concentration of 240 mg/L, CM‐QAOC at a concentration of 50 mg/L and pH 8.0 gave an antiscaling ratio of more than 98%. So, CM‐QAOC could be applied as an excellent antiscaling agent. Furthermore, a detectable fluorescence of CM‐QAOC solution was observed. To understand this interesting fluorescence phenomenon and to explore the probability of its being a fluorescent tracer, the relations between the fluorescence intensities and CM‐QAOC concentrations and the pH influence on the fluorescence intensities were investigated. The results show the fluorescence intensities accorded well with the concentrations of CM‐QAOC with a detection limit of 0.6046 mg/L, and the fluorescence intensity was constant within pH 5–9; this indicated that it had the potential of its being a fluorescent tracer. Thus, CM‐QAOC could be applied as an antiscaling water‐treatment chemical and as a fluorescence tracer directly without any further modifications. It could be self‐traced online and in real time with its own fluorescence, although more work should be done to investigate its fluorescent mechanism and its tracing properties in detail. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42518.     

Biocompatibility and antibacterial activity of chitosan and hyaluronic acid immobilized polyester fibers

Poly(ethylene terephthalate) (PET) fibers were treated with ⁶⁰Co‐γ‐ray and grafted with acrylic acid. The resulting fibers were further grafted with chitosan (CS) via esterification. Afterward, hyaluronic acid (HA) was immobilized onto CS‐grafting fibers. The antibacterial activity of CS against S. aureus, E. coli, and P. aeruginosa was preserved after HA‐immobilization. After immobilizing HA, the L929 fibroblasts cell proliferation was improved forCS‐grafting PET fiber. The results indicate that by grafting with CS and immobilizing with HA, PET fibers not only exhibit antibacterial activity, but also improve the cell proliferation for fibroblast. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 220–225, 2007     

Cationic polyelectrolytes from natural building blocks of chitosan and inulin

Novel chitosan-N-inulin graft copolymers with different degree of substitution (DS) of chitosan were synthesized via water-soluble 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide mediated reaction. Chemical structure and composition of the chitosan derivatives was confirmed by chemical analysis, FT-IR, XPS, ¹H and ¹³C NMR spectroscopy, and potentiometry. Chitosan–inulin copolymers were high-molecular-weight hydrophilic products soluble in water in a wide pH range forming extraordinary viscous solutions. Intrinsic viscosity of N-modified chitosans was sharply suppressed by added electrolyte and had tendency to decrease at higher DS of chitosan. pK_α values of the chitosan–inulin copolymers determined from potentiometric titration data using Henderson–Hasselbalch equation were in the range 6–7 slightly increasing at higher DS. Novel water-soluble chitosan copolymers retained cationic properties of chitosan and could be used as surface conditioners.     

Physical properties of water‐borne polyurethane blended with chitosan

Water‐borne polyurethanes based on 4,4‐diphenylmethane diisocyanate, poly(butylene adipate), and chain extender N‐methyldiethanolamine (MDEA) that provided tertiary amine groups were synthesized. The polyurethane–chitosan (PU/CS) blends can be dissolved in the acetic acid and cast into films. The mechanical properties including tensile strength and elongation, as well as the water absorption and thermal properties of the PU/CS films were evaluated. The tensile strength increased with the increased amount of chitosan, but the elongation decreased accordingly. The chitosan in the blends promoted the water absorption. Chitosan was more thermally‐stable than PU, as shown in the thermal gravity analysis. Chitosan also had higher crystallinity, as demonstrated by differential scanning calorimetry. The blends were partial compatible mixtures, based on the data obtained from a dynamic mechanical analysis. Biocompatibility test was conducted utilizing immortalized rat chondrocytes (IRC). After IRC were seeded onto the PU/CS films for 1.5 and 120 h, the number of cells was counted and the morphology of cells was observed by light microscopy and scanning electron microscopy. Blends containing 30% chitosan had more cells attached initially. However, the blends containing more than 70% chitosan appeared to promote the cell proliferation. IRC were round on PU/CS films with more PU, but spread when the chitosan content in blends was higher. Overall, PU/CS films with more chitosan had better mechanical properties as well as biocompatibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2683–2689, 2007     

Preparation of porous chitosan/agarose microsphere and its R‐phycoerythrin release properties

The chitosan microspheres (CS‐CL) were prepared by suspension crosslinking method and used as carriers of R‐phycoerythrin (R‐PE). In this study, R‐PE was loaded in the microspheres and released in vitro. The effects of pH value, temperature, ionic strength, and R‐PE concentration on loading efficiency and release behavior were discussed. A novel microsphere that contained agarose (CS‐AR MP) was prepared and the basic loading and releasing behavior for R‐PE of this kind of new microspheres were also investigated. The results showed that all these chitosan microspheres have the ability to control‐release R‐PE. The addition of agarose may somewhat accelerate the release rate of R‐PE from microspheres and reduce the capacity of adsorption for R‐PE. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2759–2766, 2007     

Stoichiometric and nonstoichiometric polyelectrolyte complex of chitosan and polyethyleneglycol‐monosuccinate: Preparation and characterization

Stoichiometric and nonstoichiometric polyelectrolyte complex (PEC) was prepared with polyethylene glycol‐monosuccinate (PEGMS), and chitosan (CS). A series of PEGMS were synthesized by a 1 : 1 mol ratio between PEG and succinic anhydride. Then, the novel PEC was prepared by a various mole reaction of the above synthesized PEGMS and CS. The physicochemical properties of the synthesized PEC was characterized by using elemental analysis, FTIR, ¹H, and ¹³C nuclear magnetic resonance, dissolution behavior, and phase transition phenomenon. Furthermore, some properties of the PEC obtained were analyzed by UV‐Visible spectrometry, wide‐angle X‐ray diffraction, differential scanning calorimeter, scanning electron microscope, and estimated solubility, and cell viability assay, respectively. It was found that the observed FTIR, ¹H, and ¹³C‐NMR data was in good agreement with the chemical structure of the prepared PEGMS and PEC. The dissolution behaviors of nonstoichiometric PEC were found to depend on the pH of the solution as well as on the PEGMS/CS composition. The study of MTT assay suggested that the viability of HepG2 human hepatoblastoma cell on PEC were increased significantly in accordance with mole ratio of CS. As the results, the obtained several product is a useful intermediate, which permits further chemical modification for the amino group of CS and may have potential applications in biocompatible or cosmetic systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Grafting of poly(3‐hydroxyalkanoate) and linoleic acid onto chitosan

Poly(3‐hydroxy octanoate) (PHO), poly(3‐hydroxy butyrate‐co‐3‐hydroxyvalerate) (PHBV), and linoleic acid were grafted onto chitosan via condensation reactions between carboxylic acids and amine groups. Unreacted PHAs and linoleic acid were eliminated via chloroform extraction and for elimination of unreacted chitosan were used 2 wt % of HOAc solution. The pure chitosan graft copolymers were isolated and then characterized by FTIR, ¹³C‐NMR (in solid state), DSC, and TGA. Microbial polyester percentage grafted onto chitosan backbone was varying from 7 to 52 wt % as a function of molecular weight of PHAs, namely as a function of steric effect. Solubility tests were also performed. Graft copolymers were soluble, partially soluble or insoluble in 2 wt % of HOAc depending on the amount of free primary amine groups on chitosan backbone or degree of grafting percent. Thermal analysis of PHO‐g‐Chitosan graft copolymers indicated that the plastizer effect of PHO by means that they showed melting transitions T_ms at 80, 100, and 113°C or a broad T_ms between 60.5–124.5°C and 75–125°C while pure chitosan showed a sharp T_m at 123°C. In comparison of the solubility and thermal properties of graft copolymers, linoleic acid derivatives of chitosan were used. Thus, the grafting of poly(3‐hydroxyalkanoate) and linoleic acid onto chitosan decrease the thermal stability of chitosan backbone. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:81–89, 2007     

Interpolymer complex microparticles based on polymethacrylic acid‐chitosan for oral insulin delivery

In the present study, microparticles composed of polymethacrylic acid‐chitosan (PMAA‐CS) were prepared by a novel interionic gelation method. Free‐radical polymerization of methacrylic acid was carried out in the presence of CS, using a water‐soluble initiator, and application of these microparticles toward oral insulin delivery was evaluated. Microparticles obtained were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) studies. From SEM studies, it was observed that microparticles had an aggregated morphology with size ～20 μm, while FTIR confirmed the presence of ionic interaction between PMAA and CS chains. Protein loading was done by diffusion filling method, and from in vitro release study, it was observed that insulin‐loaded microparticles displayed a pH depended release profile at alkaline/acidic pH. Microparticles exhibited sustained release of insulin for 3–4 h at neutral pH, and enzyme linked immunosorbent assay (ELISA) proved that encapsulated protein maintained 100% biological activity at neutral pH. Preliminary study suggests that these microparticles can serve as good candidate for oral protein delivery. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 506–512, 2006     

Preparation of photoluminescence films containing rare earth complexes by UV photograft polymerization

To avoid the fluorescence quenching resulting from the uneven dispersion of fluorescent rare earth complexes in photoluminescence films, which were prepared by blending until recently, photoluminescence films were prepared in which the chemical bond combination occurs between the fluorescent rare earth complexes and the macromolecular material. Acrylic acid (AA) was grafted onto polyethylene (PE) film through liquid‐phase UV photograft polymerization. Then the grafted films (PAA‐g‐PE) were reacted with a solution of Eu³⁺ and thenoyltrifluoroacetone (TTA) in alcohol–water and with a solution of Tb³⁺ and acetylacetone (AcAc) in chloroform–water, respectively. Thus, red (Eu³⁺–TTA–PAA‐g‐PE) and green (Tb³⁺–ACAC–PAA‐g‐PE) photoluminescence films were obtained. The fluorescence and infrared spectra of the photoluminescence films were recorded. Compared with their corresponding solid fluorescent complexes, both the excitation and emission wavelengths of the photoluminescence films prepared in this way had been changed remarkably, indicating that the fluorescent rare earth complexes had been chemically bonded onto the PE film. Moreover, the effects of the conditions (including pH value, reaction time, and temperature) of the reaction of the grafted film with the solution containing Eu³⁺ and TTA on the fluorescence intensity of the red photoluminescence film were investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 662–667, 2003     

Synthesis and rheological behavior of a novel N‐sulfonate ampholyte chitosan

Modified chitosan derivatives with different degrees of substitution varying from 0.17 to 0.96 were synthesized by the heterogeneous reaction of chitosan with 3‐chloro‐2‐hydroxy propanesulfate in a neutral aqueous solution. The modified chitosans with a degree of substitution higher than 0.36 were soluble in water, whatsoever the pH. The structures of the polymers were characterized by Fourier transform infrared and ¹H‐nuclear magnetic resonance spectroscopies. The potentiometric titration revealed that the modified chitosan had an isoelectric point at around pH = 5.7, and its rheological behaviors in aqueous solution were studied under different conditions. The results showed that the modified chitosan had typical polyampholyte characteristics, which exhibited polyelectrolyte effect at pH = 1.7 or 13 and antipolyelectrolyte effect at pH = 8. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

靶向壳聚糖基因载体与水溶性量子点的自组装

将透明质酸(HA)接枝到四种不同分子量的壳聚糖(CS)上,获得了靶向壳聚糖基因载体。将CS及接枝CS分别与水溶性量子点(QDs)自组装,研究发现,相对于纯QDs,CS/QDs复合物及接枝CS/QDs复合物的荧光强度均明显增强,荧光发射峰位发生红移。复合物呈核/壳结构,QDs被包裹在核内。和CS/QDs复合物相比,接枝CS/QDs复合物的尺寸更小,分布更为均一。     

Synergistic removal of Cu(II) and nitrazine yellow dye using an eco‐friendly chitosan‐montmorillonite hydrogel: Optimization by response surface methodology

A comprehensive feasibility study on adsorption of Cu(II) and a water‐soluble nitrazine yellow (NY) dye by chitosan‐montmorillonite (CS‐MMT) hydrogel as the biosorbent was investigated as a function of biosorbent dosage, initial concentration, pH, temperature, and the presence of salts. Box–Behnken methodology was applied to optimize the adsorption experiments. Maximum adsorption values were determined as 132.74 mg/g and 144.41 mg/g at pH = 5.0, for Cu(II) and NY dye, respectively. Equilibrium isotherms of Langmuir and Freundlich were analyzed by the non‐linear regression model. The equilibrium data were well described by Freundlich model and the adsorption process well fitted pseudo‐second order kinetics. The enthalpy change of adsorption (ΔH°) were calculated as ?3.78 kJ/mol and ?5.75 kJ/mol for Cu(II) and NY dye, respectively, indicating that the adsorption processes were exothermic. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43664.     

Electrospinning of flux‐enhanced chitosan–poly(lactic acid) nanofiber mats as a versatile platform for oil–water separation

Environmentally friendly chitosan (CS)–poly(lactic acid) (PLA) nanofiber mats were designed and constructed by an electrospinning strategy. Studies on the wettability of the CS–PLA nanofiber mats showed that they possessed excellent hydrophobic and oleophilic properties in the pH range 1–12. A layered oil–water mixture was separated by CS–PLA nanofiber mats, and the oil flux of the mats collected by #10 stainless steel wire mesh (sample P‐10) was up to 511.36 L m^?2 h^?1, which was approximately 25 times higher than that of the mats collected by #0 stainless steel wire meshes (sample P‐N). The superior properties of the CS–PLA nanofiber mats may have been due to their tunable porous structure and fine flexibility. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45830.