Fracture Behavior and Biocompatibility of Cellulose Nanofiber-Reinforced Poly(vinyl alcohol) Composite Hydrogels Cross-Linked with Borax.

We investigated the fracture behavior of cellulose nanofiber (CNF)-reinforced poly(vinyl alcohol) (PVA) hydrogels cross-linked with borax and the effect of freeze-thaw (FT) cycles on it. The CNF/PVA/Borax hydrogel not subjected to FT achieved a fracture energy of 5.8 kJ m and a dissipative length of 2.

Study of chondrogenesis of umbilical cord mesenchymal stem cells in curdlan- poly(vinyl alcohol) composite hydrogels and its mechanical properties of freezing-thawing treatments.

The curdlan gel is a natural material produced by bacteria. It utilizes chemical cross-linking reactions to form a 3D porous composite hydrogel, increasing its porosity and water content, and improving its mechanical properties. It can be used in tissue repair and regenerative medicine.

Editorial on the Special Issue "Advances in Composite Gels".

Polymer gels are soft materials composed of a large amount of solvent (water, organic solvent, and ionic liquid) and a polymer, and they are constructed using a three-dimensional network [...

Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them.

Freezing has been widely used for long-term food preservation. However, freezing-thawing (FT) treatment usually influences the texture and structure of food gels such as konjac. For their texture control after FT treatment, it is important to clarify the structural change of food gels during the FT process.

Mechanical Performance of Corn Starch/Poly(Vinyl Alcohol) Composite Hydrogels Reinforced by Inorganic Nanoparticles and Cellulose Nanofibers.

We investigated the mechanical properties of corn starch (CS)/poly(vinyl alcohol) (PVA)/borax hydrogels reinforced by clay platelets, silica (SiO) nanospheres, or cellulose nanofibers (CNFs). The effects of these reinforcing agents on the tensile properties of the hydrogels were quite different; the fracture stress of SiO/CS/PVA/borax composite hydrogels increased with SiO concentration, whereas that of clay/CS/PVA/borax composite hydrogels was high at a low clay concentration but low at high clay concentrations; for CNF/CS/PVA/borax composite hydrogels, although the elastic modulus was highly enhanced by adding CNF, the fracture stress was very low because of the stress relaxation during the elongation. This result came from differences in the dispersibility of each filler and the reinforcing ability.

Robust and Highly Stretchable Chitosan Nanofiber/Alumina-Coated Silica/Carboxylated Poly (Vinyl Alcohol)/Borax Composite Hydrogels Constructed by Multiple Crosslinking.

We investigated the mechanical and structural properties of composite hydrogels composed of chitosan nanofiber (ChsNF), positively charged alumina-coated silica (ac-SiO) nanoparticles, carboxylated poly (vinyl alcohol) (cPVA), and borax. ChsNF/cPVA/borax hydrogels without ac-SiO exhibited high Young's modulus but poor elongation, whereas cPVA/ac-SiO/borax hydrogels without ChsNF had moderate Young's modulus but high elongation. ChsNF/ac-SiO/cPVA/borax hydrogels using both ChsNF and ac-SiO as reinforcement agents exhibited high extensibility (930%) and high Young's modulus beyond 1 MPa at a high ac-SiO concentration.

Mechanical Properties and Structures of Clay-Polyelectrolyte Blend Hydrogels.

Our recent studies have shown that the hydrogels prepared by blending clay, a dispersant of clay, and a polyelectrolyte (sodium polyacrylate (PAAS)) possess excellent mechanical properties. In order to clarify the mechanism of the toughness, we have so far investigated the effects of the composition, molecular mass of the polymer, and kinds of polymers on the mechanical properties. This study has focused upon the mechanical properties and structures of the clay/PAAS gels using three kinds of smectite clay minerals such as synthetic hectorite (laponite XLG), saponite (sumecton-SA), montmorillonite (kunipia-F), whose particle size becomes larger according to the sequence.

Mechanical, Swelling, and Structural Properties of Mechanically Tough Clay-Sodium Polyacrylate Blend Hydrogels.

We investigated the mechanical, swelling, and structural properties of mechanically tough clay/sodium polyacrylate (PAAS) hydrogels prepared by simple mixing. The gels had large swelling ratios, reflecting the characteristics of the constituent polymer. The swelling ratios initially increased with the increase of the swelling time, and then attained maximum values.

A structural study of an organogel investigated by small-angle neutron scattering and synchrotron small-angle X-ray scattering.

We investigated structures of 12-hydroxystearic acid (12-HSA) gels in a wide temperature range from the gel to the sol states and the gelation process by means of small-angle neutron scattering (SANS) and time-resolved synchrotron small-angle X-ray scattering (SAXS), respectively. The SANS result shows that the size of the cross section of the crystalline fibers in the gel was not affected much by temperature change, although the density of the fibers decreased with the increase of temperature even in the gel state. The SANS profiles at various temperatures and compositions were well reduced by the product of the volume fraction of the fiber and the square of the scattering contrast.

Reversible chain association/dissociation via a CO2 responsive crosslinking/decrosslinking system.

Reversible chain association/dissociation phenomenon via CO(2) responsive crosslinking/decrosslinking was detected in aqueous solutions of polyallylamine (PAA). The chain association/dissociation behavior was reversible and useful in the synthesis of porous crosslinked polystyrene, which suggested potential utility in the area of CO(2)-responsive separable adhesives, switches and sensors.

Viscoelastic effects on early stage of spinodal decomposition in dynamically asymmetric polymer blends.

Spinodal decomposition induced by a rapid pressure change was investigated for a dynamically asymmetric polymer blend [deuterated polybutadiene (DPB)/polyisoprene (PI)] with a composition of 50/50 wt/wt by using time-resolved small angle neutron scattering. The time change in the scattered intensity distribution with wave number (q) during the spinodal decomposition was found to be approximated by the Doi-Onuki theory [M. Doi and A.

Viscoelastic effects in relaxation processes of concentration fluctuations in dynamically asymmetric polymer blends.

Relaxation processes of the concentration fluctuations induced by a rapid pressure change were investigated for a dynamically asymmetric polymer blend [deuterated polybutadiene (DPB)/polyisoprene (PI)] with a composition of 50-50 by weight by using time-resolved small-angle neutron scattering. The pressure change was carried out inside the single-phase of the blend with the cell designed for polymeric systems under high pressure and temperature. Time change in the scattered intensity distribution with wave number (q) during the relaxation processes was found to be approximated by Cahn-Hilliard-Cook linearized theory.