Facile preparation of low swelling,high strength,self-healing and pH-responsive hydrogels based on the triple-network structure

A polyacrylic acid(PAA)/gelatin(Gela)/polyvinyl alcohol(PVA)hydrogel was prepared by copolymerization,cooling,and freezing/thawing methods.This triplenetwork(TN)structure hydrogel displayed superior mechanical properties,low swelling ratio and self-healing properties,The superior mechanical properties are attributed to the triple helix association of Gela and PVA crystallites by reversible hydrogen bonding.The characterization results indicated that the fracture stress and the strain were 808 kPa and 370% respectively,while the compression strength could reach 4443 kPa and the compressive modulus was up to 39 MPa under the deformation of 90%.The hydrogen bonding in PVA contributed to maintain and improve the self-healing ability of hydrogels.Every type of hydrogels exhibited a higher swelling ratio under alkaline conditions,and the swelling ratios of PAA,PAA/PVA and PAA/Gela hydrogels were 27.71,12.30 and 9.09,respectively.The PAA/Gela/PVA TN hydrogel showed the lowest swelling ratio(6.57)among these hydrogels.These results indicate that the novel TN hydrogels possess good environmental adaptability and have potential applications in the biomedical engineering and sensor field.

Novel robust cellulose-based foam with pH and light dual-response for oil recovery

We fabricated pH and light dual-responsive adsorption materials which could induce the transition of surface wettability between hydrophobicity and hydrophilicity by using ATRPo The structure and morphology of adsorption materials were confirmed by ATR-FTIR, XPS, TGA and SEM. It showed that the modified cellulose （CE）- based foam was hydrophobic, which can adsorb a range of oils and organic solvents in water under pH = 7.0 or visible light irradiation （λ〉500 nm）. Meanwhile, the wettability of robust CE-based foam can convert hydrophobicity into hydrophilicity and underwater oleophobicity under pH = 3.0 or UV irradiation （λ = 365 nm）, giving rise to release oils and organic solvents. Most important of all, the adsorption and desorption processes of the modified CE-based foam could be switched by external stimuli. Furthermore, the modified CE-based foam was not damaged and still retained original performance after reversible cycle repeated for many times with variation of surface wettability. In short, it indicates that CE-based foam materials with switchable surface wettability are new responsive absorbent materials and have owned potential application in the treatment of oil recovery.

Environmentally benign chitosan as reductant and supporter for synthesis of Ag/AgCI/chitosan composites by one-step and their photocatalytic degradation performance under visible-light irradiation

A novel Ag/AgCl/chitosan composite photocatalyst was successfully prepared by a simple one-step method. During this progress, environmentally benign chitosan not only served as reductant to reduce Ag＋ to Ag0 species, but also acted as supporter for Ag/AgCI nanoparticles. XRD, SEM, EDX, UV-vis DRS and XPS were employed to characterize the as-prepared simples. SEM images of Ag/AgCI/chitosan composites revealed that Ag/AgCI nanoparticles were successfully loaded onto chitosan without obvious aggregation. All Ag/AgCI/chitosan composites exhibited efficient photocatalytic activity for the degradation of rhodamine B （RhB） under visible-light irradiation. The result of photocatalytic degradation experiment indicated that 20% of the mass ratio of AgCI to chitosan was the optimum, and after 40 min photocatalytic reaction, the degradation rate reached about 96%.

One-step synthesis and self-assembly behavior of thermo-responsive star-shaped β-cyclodextrin-（P（M EO2MA-co-PEGMA））21 copolymers

A novel β-cyclodextrin-poly（2-（2-methoxyethoxy）ethyl methacrylate）-co- poly（ethylene glycol） methacrylate （abbreviated as： β-CD-（P（MEO2MA-co-PEGMA））21） was prepared by using the one-step strategy, and then the star-shaped copolymers were used in the atom transfer radical polymerization （ATRP）. The structure of star-shaped β- CD-（P（MEO2MA-co-PEGMA））21 copolymers were studied by FTIR, 1H NMR and gel permeation chromatography （GPC）. The star-shaped copolymers could self-assembled into micelles in aqueous solution owing to the outer amphiphilic β-CD as a core and the hydrophilic P（MEO2MA-co-PEGMA） segments as a shell. These thermo-responsive starshaped copolymers micelles exhibited lower critical solution temperature （LCST） in water, which could be finely tuned by changing the feed ratio of MEO2MA to PEGMA. The LCST of star-shaped β-CD-（P（MEO2MA-co-PEGMA））21 copolymer micelles were increased from 35℃ to 58℃ with the increasing content of PEGMA. The results were investigated by DLS and TEM. When the temperature was higher than corresponding LCSTs, the micelles started to associate and form spherical nanoparticles. Therefore, β- CD-（P（MEO2MA-co-PEGMA））21 star-shaped copolymer micelles could be potentially applied in nano-carrier, nano-reactor, smart materials and biomedical fields.

Folate-conjugated pH-responsive nanocarrier designed for active tumor targeting and controlled release of doxorubicin

A novel type of amphiphilic pH-responsive folate-poly（ε-caprolactone）- block-poly（ 2-hydroxyethylmethacrylate ）-co-poly（ 2-（ dimethylamino ）-ethylmethacrylate ） （FA-PCL-b-P（HEMA-co-DMAEMA）） （MFP） block copolymers were designed and synthe- sized via atom transfer radical polymerization （ATRP） and ring opening polymerization （ROP） techniques. The molecular structures of the copolymers were confirmed with IH NMR, FTIR and GPC measurements. The critical micelle concentration （CMC） of MFP in aqueous solution was extremely low （about 6.54 mglL）. The in vitro release behavior of DOX-Ioaded micelles was significantly accelerated when the pH value of solution decreased from 7.4 to 5.0. In vitro antitumor efficiency was evaluated by incubating DOX- loaded micelles with Hela cells. The results demonstrated that this copolymer possessed excellent biocompatibility, and FA-decorated micelles MFP showed higher cellular uptake than those micelles without the FA moiety, indicating their unique targetability. These folate-conjugated biodegradable micelles are highly promising for targeted cancer chemothe-rapy.

A novel black TiO2/ZnO nanocone arrays heterojunction on carbon cloth for highly efficient photoelectrochemical performance

ZnO nanocone arrays(NCAs)decorated with black TiO2 nanoparticles(BTiO2 NPs)were uniformly anchored on the surface of carbon cloth(CC)directly by a simply electrochemical deposition method.Thus a novel B-TiO2 NPs/ZnO NCAs-CC hierarchical heterostructure was formed.It displayed superior performance and achieved a higher photocurrent over 0.4 mA·cm^-2 before the onset of the dark current,attributed to the separation of the photogenerated electron-hole pair.Based on the B-TiO2 NPs/ZnO NCAs-CC heterostructure,the catalyst was fabricated for promoting the separation of charge carriers.Moreover,the introduction of Ti^3+ and oxygen vacancies on the surface of TiO2 NPs expanded the absorption band edge and enhanced the electrical conductivity as well as the charge transportation on the catalytic surface.It indicates that the B-TiO2 NPs/ZnO NCAs-CC composite is beneficial to the improvement of the photoelectrochemical(PEC)activity.

Synthesis of pH-responsive triazine skeleton nano-polymer composite containing AIE group for drug delivery

We exploited a unique porous structure of the nano-covalent triazinepolymer(NCTP)containing aggregation-induced emission(AlE)group to achievecontrolled release and drug tracking in tumor acidic microenvironment.NCTP wassynthesized by the Friedel-Crafts alkylation and the McMurry coupling reaction.It notonly had strong doxorubicin(DOX)-loading capacity due to its high specific surface areaand large pore volume,but also showed the significant cumulative drug release as aresult of the pH response of triazine polymers.NCTP was induced luminescence aftermass accumulation near tumor cells.Besides,it had excellent biocompatibility andobvious antineoplastic toxicity.The results demonstrate that NCTP as a utility-type drugcarrier provides a new route for designing the multi-functional drug delivery platform.