粉煤灰混凝土中凝胶水合物稳定存在的热力学条件探讨

混凝土中凝胶产物的稳定性直接影响到混凝土构件的安全耐久性。本文以研究粉煤灰混凝土中水合硅酸钙、水合铝酸钙的稳定条件为目的，通过对水合凝胶产物水解反应的标准自由焓变的计算，讨论了在自然环境水的侵蚀下，粉煤灰混凝土中某些凝胶产物稳定存在的热力学条件。

Study on Synthesis and Chloramphenicol Release of Poly（2-hydroxyethylmethacrylate-co-acrylamide） Hydrogels

In this article, poly（2-hydroxyethylmethacrylate-co-acrylamide） hydrogels were synthesized by bulk free-radical copolymerization of 2-hydroxyethylmethacrylate （HEMA） and acrylamide （AAm） for soft contact lens（SCL）-based ophthalmic drug delivery system. The copolymer was characterized with FT-IR and SEM, the swelling property of the hydrogels were studied by gravimetrical method, and chloramphenicol was used as a model drug to investigate drug release profile of the hydrogels. The results showed that poly（2-hydroxyethylmethacrylateco-acrylamide） hydrogels were transparent and useful SCL biomaterial, the water content increased as AAm content increase and pH decrease, and in the same way, hydrogel composition affected chloramphenicol release process too. Migration rate of chloramphenicol increased as the AAm content in the hydrogels increased in the first stage of diffusion process, whereas there was no significant difference thereafter.

Modulation of Self-healing of Polyion Complex Hydrogel by Ion-specific Effects

We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.

PREPARATION AND PROPERTIES OF CLAY/POLY（N-ISOPROPYLACRYLAMIDE-co-A CRYL AMIDE） NANOCOMPOSITE HYDROGELS

A series of clay/poly（N-isopropylacrylamide-co-acrylamide） nanocomposite hydrogels （S-N-M gels） have been successfully prepared by in situ polymerization. The mechanical properties, swelling behavior of S-N-M gels and the transparency changes during polymerization of S-N-M gels have been systematically investigated. Compared to traditional hydrogels, S-N-M gels show excellent tensile properties and their swelling ratio increases with increasing acrylamide （AAm） content. The results of stress relaxation indicate that the stress loss decreases with increasing AAm content. It was surprisingly found that the transparency during all S-N-M gel synthesis changes abruptly, and the changes become more abrupt with increasing N-isopropylacrylamide content. It was concluded that the fact may be related to the hydrophilicity of copolymers. The weaker the hydrophilicity of copolymer, the more apparent the transparency change during S-N-M gels polymerization. We believe the relationship between hydrophilicity of copolymer and transparency changes will help to design novel nanocomposite hydrogels.

Crystallization of calcium carbonate in hydrogels in presence of meso-tetrakis (4-hydroxylphenyl) porphyrin

Organic matrices play an important role in biomineralization process. In order to explore the effect of both meso-tetrakis (4-hydroxylphenyl) porphyrin (THPP) and hydrogels on calcium carbonate mineralization,and consequently synthesize functional materials based on porphyrin and calcium carbonate with tunable shapes and optical properties,a new kind of biomimetic mineralization system which combined THPP with three biopolymer hydrogels (gelatin,agarose and calcium alginate gels) was designed and investigated. A carbonate diffusion method based on the generation of CO2 by slow decomposition of ammonium hydrogen carbonate was adopted for calcium carbonate crystallization. The results show that both gelatin and alginate hydrogels exhibit the ability of stabilizing vaterite,while agarose only induces the formation of calcite. With participation of THPP in the mineralization environments,calcite is favored in all these hydrogels,while the crystal morphologies are greatly different from each other. These results indicate the perspective of THPP in regulating calcium carbonate crystallization and also provide a new strategy for fabricating advanced functional materials with controlled morphology and tunable optical properties based on calcium carbonate and THPP.

Preparation of Thermosensitive Chitosan Formulations Containing 5-Fluorouracil/Poly-3-hydroxybutyrate Microparticles Used as Injectable Drug Delivery System

The auto-gelling and drug release properties of the thermosensitive chitosan-β-glycerophosphate formulation were investigated. According to rheological study, gelation lag time of chitosan/β-glycerophosphate （GP） solutions varied from 2 to 60min with different deacetylation degree of chitosan, pH, gelation temperature, and the particles in the sol. The gelation properties were also found to influence the release profilles of a hydrophilic drug, 5-fluorouracil （5-FU）. Morphological examination by scanning electron microphotography demonstrated that large ＂pores＂ occurred during the gel-forming process, which created hydrophilic environment and led to the rapid initial release of the drug （85% in f＇LrSt 8h）. Poly-3-hydroxybutyrate （PHB）, a biodegradable material, was applied here as scaffold to capture 5-FU into microparticles with high encapsulation efficiency by solvent-nonsolvent method. Combination of these microparticles into the chitosan-β-GP formulation could drop the rapid initial release from 85% down to 29% in the optimized PHB content （75%, by mass）. The release could sustain for about 10 months. Tiffs study provided an understanding of the potential of injectable implant using thermosensitive chitosan-β-GP formulation containing PHB based particles for the water soluble drugs that need the property of long-term delivery.

A MODEL FOR THE RELEASE BEHAVIOR OF DRUGS FROM HYDROGEL NANOPARTICLE

A model to correlate and predict the release behavior of drugs from hydrogel nanoparticles is presented in this paper. The nanoparticle is considered as a combination of a shell of an elastic semipermeable membrane and a core of a fluid phase （After swelling equilibrium）. The fluid core consists of network building materials and other components that are able to partition in hydrogel nanoparticle phase and surrounding coexisting liquid phase, and is enveloped by the membrane shell. The excess Gibbs energies of the hydrogel nanoparticle phase and the surrounding coexisting fluid phase are expressed e.g. using UNIQUAC equation with ＂free-volume＂ contribution for non-ionic solution and VERS-model for ionic one. The elastic properties of polymer network could be described, for example, by the ＂phanWm network＂ theory.

Effect of distortion degree on the hydration of red mud base cementitious material

The interaction of Si anions with Al sites during the hydration process was observed by NMR, IR and SEM to understand the reaction mechanism of the hydrates formation mixed with oil shale calcined at different temperatures. As the reaction progressed, the coordination of Al （Ⅳ, Ⅴ, and Ⅵ） changed almost completely to Ⅳ, when mixed with oil shale calcined at 700 ℃. However, when mixed with oil shale calcined at 400 ℃, some 6-coordination of Al still remained in the hydrates. Under the function of alkaline solutions, which were produced with the hydration of clinker, a certain amount of Si and Al atoms dissolved or hydrolyzed from aluminosilicate, formed geomonomers in solutions, and then polycondensed to form networks.

New Extracellular Bacillus subtilis Lectins with Sialic Acid-Specificity

The purpose of this work is to perform a detailed study of carbohydrate specificity of the new extracellular bacilli lectins which is considered to determine mechanisms of the lectins action. Sources of lectins were bacterial strains from Ukrainian collection of microorganisms. The optimized protocol of bacilli lectins isolation and purification included precipitation with ammonium sulfate with subsequent gel filtration chromatography on Sepharose CL-6B. Hemagglutinating activity of bacilli lectins and their fine carbohydrate specificity to sialic acids and their derivatives as well as sialic asid-containing and asialic glycoconjugates were studied. The ability of extracellular bacilli lectins to discriminate a- and 13-conformation of carbohydrate molecule and the type of connection between the monomers was determined. Studied lectins showed the most affinity to glycoconjugates containing both types of sialic acids （N-acetylneuraminic acid （Neu5Ac） and N-glycolylneuraminic acid （NeuGc）） and it is supposed to be a basis of their diagnostic and analytical potential.

Muscle-inspired ion-sensitive hydrogels with highly tunable mechanical performance for versatile industrial applications

Human muscles are notably toughened or softened with specific inorganic ions.Inspired by this phenomenon,herein we report a simple strategy to endow hydrogels with comparable ion-responsive mechanical properties by treating the gels with different ionic solutions.Semi-crystalline poly(vinyl alcohol)hydrogels are chosen as examples to illustrate this concept.Similar to muscles,the mechanical property of hydrogels demonstrates strong dependence on both the nature and concentration of inorganic ions.Immersed at the same salt concentration,the hydrogels treated with different ionic solutions manifest a broad-range tunability in rigidity(Young’s modulus from 0.16 to 9.6 MPa),extensibility(elongation ratio from 100% to 570%),and toughness(fracture work from 0.82 to 35 MJm^(-3)).The mechanical property well follows the Hofmeister series,where the“salting-out”salts(kosmotropes)have a more pronounced effect on the reinforcement of the hydrogels.Besides,the hydrogels’mechanical performance exhibits a positive correlation with the salt concentration.Furthermore,it is revealed both the polymer solubility from amorphous domains and polymer crystallinity from crystalline domains are significantly influenced by the ions,which synergistically contribute to the salt-responsive mechanical performance.Benefitting from this feature,the hydrogels have demonstrated promising industrial applications,including tunable tough engineering soft materials,anti-icing coatings,and soft electronic devices.

Underwater flexible mechanoreceptors constructed by anti-swelling self-healable hydrogel

Wet-resistant flexible electronics have acquired increasing attention on applications in wet environments,such as sweaty skin, rainy weather, biological fluids, and underwater. However, it remains challenging to achieve nonswelling and underwater self-healing hydrogel sensors for the mechanical perception in aqueous solutions. Herein, a selfhealing and non-swellable hydrogel is successfully fabricated,which presents an automatically healing behavior in various aquatic environments, including deionized water, seawater,sweat, alkali and acidic aqueous solutions. Moreover, the hydrogel demonstrates high stretchability and stable electromechanical sensing properties in water. Furthermore, an electronic skin is designed with the features of fast responsiveness, reliability, and high sensitivity for detecting breathing, speaking, coughing, and diverse body movements. The self-healing hydrogel sensors enable a brilliant mechanical sensibility for detecting a series of dynamic stimuli in air and underwater, even after the healing of fracture interface in water. The underwater self-healing and anti-swelling hydrogel would provide enticing potential on various stable electronic devices for aquatic environments, such as implantable electrodes, triboelectric nanogenerators, and underwater soft robotics.

A high strength pH responsive supramolecular copolymer hydrogel

Constructing high strength pH sensitive supramolecular polymer hydrogel remains very challenging due to the unavoidable network swelling caused by ionization of acid or basic groups at a specified pH.In this work,we proposed a simple and very convenient approach to fabricate high strength pH responsive supramolecular polymer(SP) hydrogels by one-pot copolymerization of N-acryloyl glycinamide(NAGA) and 2-vinyl-4,6-diamino-1,3,5-triazine(VDT),two feature hydrogen bonding monomers.In these PNAGA-PVDT SP hydrogels obtained,the hydrogen bonding of NAGA was shown to play a dominant role in reinforcing strength,while the hydrogen bonding of diaminotriazine served as a pH sensitive moiety.At pH 3,the mechanical properties of PNAGA-PVDT hydrogels decreased to a different extent due to the breakup of hydrogen bonding;in contrast,the hydrogel resumed the original strength while pH was raised to 7.4 because of reconstruction of hydrogen bonding.Over the selected pH range,the PNAGA-PVDT hydrogels exhibited up to 1.25 MPa tensile strength,845% breaking strain,69 kPa Young's modulus and 21 MPa compressive strength.This novel high strength pH-responsive SP hydrogels may find applications in biomedical and industrial fields.