The Construction And Mechanism Study Of Smart Hydrogel Based On Hydrophobically Modified Polymer

Recent years have witnessed an increasing interest in the development of smart hydrogels that can sense changes in their environment and accordingly adapt their function, similar to living systems. These high-performance hydrogels are expected to have diverse applications, such as drug-delivery systems, remotely actuated biosensors and shape memory materials.In this paper,a simple strategy is proposed to design and fabricate high-performance hydrogels, following the principle of the simple preparation method,the low cost and the high performance.The main innovative contribution of this thesis can be divided into the following sections:(1)The hydrophobically modified chitosan has been successfully prepared according to the schiff-base method,and the reactive conditions have been discussed.A novel, thermal-switchable self-healing hydrogel can be obtained simply by mixing the hydrophobically modified chitosan (hm-chitosan) with the thermal-responsive vesicle composed of5-methyl salicylic acid (5mS) and dodecyltrimethylammonium bromide (DTAB).Temperature stimuli points to a sol-gel phase transition in the supramolecular hydrogel and such transition can be reversibly performed for several cycles. In particular, the gelation temperature can be easily controlled by varying the ratio of DTAB to5mS. Aside from the temperature responsive ability, the original feature highlighted in this work is that such a vesicle-based hydrogel exhibits interesting self-healing feature in a matter of seconds through the autonomic reconstruction without the use of healing agent.(2) We report that the conventional responseless hydrophobically modified p(AM/C12)hydrogel can be engineered to show fascinating pH-responsive and self-healing abilities simply in combination with a responser, sodium oleate (NaOA). The use of vesicle-to-micelle transition (VMT) of a surfactant by altering the pH in a narrow range endows the reversible sol-gel transition property to the conventional responseless hydrogel. As a result, we can modulate the rheological properties of the networks from highly elastic to viscous repeatedly, as well as vary the dynamic modulus over four orders of magnitude by simply adjusting the pH. Another particular interest is that such a vesicle-loaded hydrogel displays self-healing features through the autonomic reconstruction without the use of a healing agent.(3) The successful construction of a thermogelling system for the hydrophobically modified polyacrylamide (HMPAM)/a-CD mixture is reported featuring an application to the host-guest approach. It has been shown that the thermogelling property, masked by the strong intermolecular hydrophobic interaction, can be engineered to display by means of the host-guest approach, requiring no special synthesis, no third competitive guest and no harsh conditions. The findings of this work provide the basis for understanding and controlling the properties of hydrophobically modified polymers, fostering their use in a wide range of applications, including micro-fluidics, controlled release, tertiary oil recovery and smart materials.