Search

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.)

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.)

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.)

Starch‐based dual photo‐functional hydrogel (SDPH) was obtained via incorporating the azo group onto the backbone of polymeric network and titanium dioxide within the gel at the same time. The structure and composition of SDPH were confirmed with Fourier transform infrared spectrometer, ultraviolet‐visible (UV‐Vis) spectroscopy, thermogravimetric analysis, and energy scattering X‐ray spectroscopy. Scanning electron microscopy observation revealed that titanium dioxide was well dispersed within SDPH. It was found that SDPH not only showed a reversible light‐sensitive behavior but also possessed photo‐catalytic activity. Moreover, the dual photo‐characteristics could be modulated by simply varying the initial amount of titanium dioxide. [ABSTRACT FROM AUTHOR]

A facile synthesis route was employed to prepare starch-based hydrogels that contained highly acidic groups. The gels were obtained through the free radical cross-linking reaction between an unsaturated starch-based macromonomer and acrylic acid (AA)/sodium vinyl sulfonate or AA/itaconic acid monomer pair, and denoted as SAS or SAI. The structure of the gels was verified with FTIR, XRD, and TGA measurements. It was found that the swelling ratios of SAI and SAS depended on the feeding ratio of monomers and could be 6.6 and 12.1, respectively. Rhodamine B was bound into the gels via electrostatic interaction and able to be released again. In particular, the hydrolysis of starch was enhanced with either hydrogel. Both the encapsulation capacity for the cationic electrolyte and catalysis effect of the gels were in the order of SAS>SAI. The results indicated that the network structure and performances of the starch-based gels could be regulated by simply varying the components and ratios of monomers. [ABSTRACT FROM AUTHOR]

A tunable starch-based hydrogel was prepared by crosslinking unsaturated macromonomers in the presence of H2S. First, well-defined poly(vinyl alcohol) (PVA) was prepared by alcoholysis of poly(vinyl acetate) obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of vinyl acetate. Subsequently, carbon-carbon double bonds were incorporated onto PVA through esterification with maleic anhydride. Finally, the hydrogel was formed via concurrent electrophilic addition and thiol-ene reaction between starch maleic half-ester, unsaturated PVA and H2S using potassium persulfate as initiator at 60 °C. Elemental analysis showed the percentage of sulfur in the gel ranged from 0.86% to 1.73%, depending on the chain length of PVA. The storage modulus, loss modulus and glass transition temperature of the networks varied from 12.7 to 50.9 MPa, from 3.7 to 15.7 MPa and from 57.0 to 71.8 °C, respectively. Both the swelling and release behavior of the gels were also modulated by changing the unsaturated PVA component. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Starch is a natural polymer, which has many unique properties. It has been utilized to prepare hydrogels and received growing attention. Starch-based hydrogels (SH) are attractive and widely applied in a variety of fields such as biomedical, food packing, and others. In this article, the developments of physical and chemical SHs in the last decade are summarized. The common approaches to prepare hydrogels are briefly elucidated. Subsequently, the SHs obtained by chemical and physical cross-linking methods are described. Then, the characteristics and potential applications of the SHs are introduced and correlated. Finally, suggestions about the future directions of developing SHs are presented. [ABSTRACT FROM AUTHOR]

A structure-exact starch-based xanthate agent was prepared and used as chain transfer agent to mediate RAFT polymerization of vinyl acetate, which offered a convenient way to well control the structure and composition of starch- g-poly(vinyl acetate). The structures of the intermediate and the polymer were verified with FTIR and 1H-NMR. Gel permeation chromatography measurement results indicated that the polymerization was performed as expected. It was found that the relationship between number average molecular weight and monomer conversion was linear. The polydispersity index of grafted side-chain ranged from 1.19 to 1.53 and most of them were around 1.2. There was one more degradation stage appeared on the thermogravimetric analysis profile of starch- g-poly(vinyl acetate) than that of starch. TEM observation exhibited that the product was able to self-assemble into micelles in aqueous solution, which suggested the copolymer was amphiphilic. Both the thermal and amphiphilic properties demonstrated the starch- g-poly(vinyl acetate) was successfully synthesized as well. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The article examines the ionic self-assembly and properties of a novel polysaccharide-based polyelectrolyte complex (PEC) of maleic starch half-ester acid (MSA) with chitosan (CS) precipitated from an aqueous solution. The purpose is to find a better way of delivering bioactive molecules via biodegradable PECs. It presented experimental results which indicated that the self-assembly of the biodegradable PEC was due to the electrostatic interaction between the cationic CS and the anionic MSA.

Highlights • Layer-by-layer (LbL) assembly between polyanion and metal ion is carried out. • The driving force for such an LbL assembly is the electrostatic interaction. • Starch-based derivative containing carboxyl groups is employed as the anion. • Polysaccharide-based functional multilayer can be formed via this facile route. Abstract 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. [ABSTRACT FROM AUTHOR]