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A kind of novel unique semi-IPN was formed through facile radical cross-linking reaction between PVA-based macromonomer (PVAM) and acrylic acid (AA) in the presence of water-soluble chitosan (WSC). WSC, PVAM and AA were dissolved in distilled water, mixed homogeneously and initiated with potassium persulphate to perform the reaction. WSC was well distributed within the chemical network, which enabled the hydrogen bonding to be formed between part of amino groups on WSC chain and some carboxylic groups on PVA-based gel. As a result, the tensile strength of WSC/PVAM-AA semi-IPN is as high as 6.25 MPa when 30 wt% WSC was fed. Both the WSC content and water content affected the mechanical properties of the semi-IPN. Hydrogen bonding imparted another characteristic, i.e. self-healing ability, to the semi-IPN. The functional groups including amino and carboxyl groups not only acted as the contributors of hydrogen bonding, but also provided the semi-IPN the third trait, pH-sensitive swelling behavior. As a result, the facilely prepared semi-IPN exhibited triple functions., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Starch-based polyelectrolyte that contained azo and carboxyl groups was prepared and applied to performed layer-by-layer (LbL) assembly with amino starch. The structure of the starch-based polyelectrolyte was characterized with UV-visible spectroscopy and 1 HNMR. UV-visible spectroscopy was also utilized to confirm the assembly characteristic of the starch-based polyelectrolyte. It was found that the adsorption intensity of the sample increased with increasing the layers. The obtained multilayer exhibited a reversible trans-cis photoisomerization when it was subjected to UV and visible light irradiation. The photoisomerization of starch-based polyelectrolyte was able to tune the fluorescence of rhodamine B, which was carried out through LbL assembly and light irradiation. These results suggested that the starch derivative was a good candidate for preparing tunable light-function materials., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The layer-by-layer (LbL) assembly between metal ion and starch-based anion driven by electrostatic interaction was investigated. Multilayer films were obtained from starch-based derivative containing carboxyl groups (SC) with copper or lead ions. It was found that the concentration of metal ion in aqueous solution decreased with increasing the layers. X-ray photoelectron spectroscopy exhibited the content of Cu(II) was higher when the surface was copper-ion-layer than that composed of SC. The surface of the film was smooth and no obvious fault plane was observed on its cross-section, which also indicated that the LbL assembly between starch-based polyanion and metal ion was carried out. Sodium alginate was adopted as another polyanion to conduct the LbL assembly. Part of metal ion was replaced with rhodamine B to fabricate composite multilayer. During such an assembly, the concentration of copper ion in aqueous solution decreased with increasing the layers as well. These phenomena suggested that the LbL assembly between polysaccharide-based polyanion and metal ion was feasible., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Lay-by-layer (LbL) assembly among water-soluble chitosan (WSC), sodium alginate (SA) and copper ion was applied to form polysaccharide-based flame retardant coating on polyester fabric. Thermogravimetric analysis (TGA) results indicated the thermal decomposition temperature of the surface-modified sample was higher than that of the original one, and increased with increasing the layers. Microscale combustion calorimetry (MCC) measurements exhibited that the heat release rate (HRR) values of the samples containing various layers were lower than that of unmodified sample and decreased as increasing layers. The peak value in HRR and total heat release of unmodified sample were 343.31 w/g and 46.11 kJ/g, while 214.29 w/g and 38.49 kJ/g for the sample containing 16-layers WSC-SA-Cu(II) respectively. The limiting oxygen index values of the samples were in the order: samples containing WSC-SA-Cu(II) layers > samples containing SA-Cu(II) layers > unmodified sample. The vertical burning reflected the sample containing WSC-SA-Cu(II) or SA-Cu(II) self-extinguished within 35 s, and the time was shorter as the sample composed of more layers. The flame retardancy of polyester fabric was significantly improved through LbL assembly of polysaccharide-based polyelectrolytes and copper ion., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Starch-based hydrogel containing azo group (SHA) was prepared through radical cross-linking reaction among starch- and PVA-based macromonomers, acrylic acid (AA) and 4-acryloyoxyazobenzene (AHAB). AHAB was prepared through an acylation reaction between acryloyl chloride and 4-hydroxyazobenzene (p-HAB), which was obtained by the diazo coupling reaction between aniline and phenol. The structure of SHA was confirmed with Fourier transform infrared spectrometer, thermogravimetric analysis and UV-Visible spectroscopy. SHA displayed pH-sensitive swelling in buffer saline. SHA film also exhibited a reversible trans-cis-trans photoisomerization behavior when they were subjected to alternative UV and visible light irradiation or dark storage. The dual-responsive characteristic was easily to be tailored via varying the initial amount of AHAB or AA., (Copyright © 2018 Elsevier B.V. All rights reserved.)

We changed the situation that chitosan was only dissolved in diluted acid through mild physical treatment. In viewing of the usual methods to modify chitosan are chemical ones, we established the approach by using a water-soluble chitosan derivative as the model polymer. Its water-solubility was modulated via changing the concentration of solution and varying the precipitants. Such a physical method was adopted to treat chitiosan. One gram chitosan was dissolved in a mixture of 100mL 10% acetic acid and 50mL methanol, and then precipitated from a precipitant consisted of 10mL ethanol and 90mL acetate ester. The treated chitosan became soluble in acid-free water completely, and its solubility was 8.02mg/mL., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Facile and mild ionic cross-linking and freezing/thawing technologies were applied to prepare double strengthened core-shell particles by using water-soluble chitosan (WSC), sodium alginate (SA) and poly(vinyl alcohol) (PVA) as starting materials. The aqueous solution contained WSC and PVA was dropped in ethanol to form beads. The beads were converted into WSC/PVA hydrogel particles by being subjected to three freeze/thaw cycles. Subsequently, ionic cross-linked hydrogel layer was formed around each WSC/PVA particle to generate core-shell particulates. Fourier transform infrared spectra confirmed the combination among various components. Dynamic mechanical thermal analysis indicated that the storage modulus of the core-shell hydrogel was improved obviously. Thermogravimetric analysis exhibited the thermal stability of the particles was also enhanced by incorporation of PVA. It was found that the particles were able to adsorb carbon dioxide, lead ion and copper ion. The adsorption capacities of dry particles toward carbon dioxide, Pb(II) and Cu(II) could reach 199.62, 39.28 and 26.03mg/g, respectively. The rates of the particles for binding Pb(II) and Cu(II) at initial stage were 26.57 and 4.30%/min, respectively. These experimental results suggested that the particles were an efficient sorbent for removing hazardous substances such as carbon dioxide and heavy-metal ions., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Water-soluble chitosan-based core-shell particles that contained changeable cores were successfully applied to anchor carbon dioxide. The entrapment capacity of the particles for carbon dioxide (EC) depended on the cores. It was found that EC of the particles contained aqueous cores was higher than that of the beads with water-soluble chitosan gel cores, which was confirmed with thermogravimetric analysis. In addition, calcium ions and sodium hydroxide were introduced within the particles to examine their effect on the entrapment. EC of the particles was enhanced with sodium hydroxide when the cores were WSC gel. The incorporation of calcium ions was helpful for stabilizing carbon dioxide through the formation of calcium carbonate, which was verified with Fourier transform infrared spectra and scanning electron microscopy/energy-dispersive spectrometry. This phenomenon meant the role of calcium ions for fixating carbon dioxide was significant., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A chain-like route was presented to create various core-shell particles with soft, aqueous or inorganic cores respectively. Water-soluble chitosan (WSC) gel particles were obtained through gelating the aqueous WSC solution of 0.02 g/mL at its isoelectric point. Then, polyelectrolyte complexes were formed and surrounded on the outer surfaces of WSC gel particles by immersing the particles in 2 wt% aqueous sodium alginate. Soft WSC cores in these core-shell particles disappeared after maintaining the particles in 1M HCl for 6h. The cores of obtained particles at this step became aqueous, and could be further transformed into inorganic ones via contacting the particles with copper sulfate and sodium sulfide aqueous solutions successively. The composition of the shell was verified with Fourier transform infrared spectroscopy. The formation of various core-shell particles was confirmed with digital photographic observation, thermogravimetric and fluorescence analyses. The whole process was a chain-like one and was able to stop at any stage to harvest a corresponding target., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A versatile water-soluble chitosan (WSC) was applied to construct two kinds of controllable functional hydrogels. Magnetic beads were prepared by physical cross-linking WSC with sodium alginate, soaking particles with ferrous chloride and being subjected to self-oxidation. Magnetic character of the beads was tunable by simply changing the initial concentration of ferrous ions. The beads could bind compounds that contained different charges. Their adsorption capacities for coomassie brilliant blue, rhodamine and hemoglobin were 1, 0.5 and 2.3mg/g respectively. Another kind of functional hydrogel was prepared through radical cross-linking reaction between WSC and a macromonomer (PVAM) derived from well-defined polyvinyl alcohol. The dynamic mechanical thermal analysis and thermogravimetric analysis results revealed that the mechanical strength and thermal stability of this hydrogel depended on the structure of PVAM. The capability to bind heavy metal ions of the hydrogel also relied on the structure of PVAM. The adsorption capacities of the hydrogels for Cu(2+) and Pb(2+) could reach 20.3 and 60.1mg/g respectively., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Versatile hydrogel particles were obtained by cross-linking of water-soluble chitosan (WSC) with sodium alginate (SA) in an acid-free medium. The structure of the particles was investigated with Fourier transform infrared spectra, differential scanning calorimetry and thermogravimetric analysis. These characterization results confirmed that the product was physically cross-linked hydrogel consisted of WSC and SA. It was found that the swelling ratio of the particles depended on the formation time, which indicated that their cross-linking degrees were easily modulated. The particles showed high capability to bind heavy metal ions, acidic gas and basic gas. The adsorption capacities of the particles could reach 88.2 and 66.0 mg/g for Cu(2+) and Pb(2+), 33.8 and 30.3 mg/g for NH3 and H2S, respectively. Especially, the existence of water significantly enhanced the adsorption capacities for NH3 and H2S. In addition, the mild formation condition made the particles suitable for encapsulating bioactive substance. The loading efficiency of the beads for hemoglobin (HB) reached close to 100%. Moreover, the release behavior of the HB-loaded particles was pH-sensitive. In contrast, HB was deactivated during encapsulating it with chitosan and sodium alginate. Obviously, such a kind of particles was an attractive adsorbent or carrier., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Polysaccharides-based functional microspheres were fabricated under mild conditions. Firstly, magnetic alginate microspheres were prepared by emulsification/internal gelation and acted as substrates. Then the multilayer composite microspheres (MCM) were obtained through the layer-by-layer assembly of the distilled water-soluble chitosan and alginate. The components, morphology, and size distribution of the microspheres were characterized by element analysis (EA), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and laser particle size analyzer (LPSA). Both EA and XPS analysis results indicated that alternate immersion was an effective method for preparing MCM. Vibrating sample magnetometer, SEM and LPSA results showed that the microspheres had good dispersion, uniform particle size and were superparamagnetic. In addition, in vitro drug release behaviors of the microspheres were investigated by using hemoglobin (HB) and Coomassie brilliant blue G250 (CBB) as model drugs. It was found that the release rates of both HB and CBB from the composite microspheres were slower than those from the substrates., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Tailor-made conjunct of methyl cellulose (MC) and polyvinyl acetate (PVAc) was synthesized through the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene click reaction. MC was firstly transferred into unsaturated MC (UMC), and then covalently connected with well-defined PVAc obtained by RAFT polymerization of vinyl acetate. The structure of the conjunct polymer (MCV) was confirmed with Fourier transform infrared spectra (FTIR) and proton nuclear magnetic resonance ((1)H NMR). Well-defined MCV was amphiphilic and able to self-assemble into size controllable micelles, which was verified with transmission electron microscopy (TEM) and size distribution analysis. It was found that the mean diameters of the micelles in aqueous solution were 105.6, 96.0 and 75.9 nm when the number average molecular weights of PVAc segments of MCV were 49,300, 32,500 and 18,200, respectively., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A novel effective starch-based adsorbent was prepared through two common reactions, which included the esterification of starch with excess maleic anhydride in the presence of pyridine and the cross-linking reaction of the obtained macromonomer with acrylic acid by using potassium persulphate as initiator. The percentage of carboxylic groups of the macromonomer ranged from 14% to 33.4%. The cross-linking degree of the adsorbent was tailored with the amount of acrylic acid which varied from 10wt% to 80wt%. Both Fourier transform infrared spectra and thermogravimetric analysis results verified the structure of the adsorbent. The maximum gel fraction and swelling ratio of the adsorbent were about 72% and 6.25, respectively, and they were able to be adjusted with the amount of monomers. The weight loss percentage of the adsorbent could reach 96.9% after immersing in the buffer solution that contained α-amylase for 14h. It was found that the adsorption capacities of the adsorbent for lead and mercury ions could be 123.2 and 131.2mg/g, respectively. In addition, the adsorbent was able to remove ca. 51-90% Pb(II) and Hg(II) ions that existed in the decoctions of four medicinal herbals., (Copyright © 2011 Elsevier B.V. All rights reserved.)