Biomimetic Preliminary Exploration Of Acid Sensitivity Starch-based Hydrogel

This thesis mainly addressed the freezing-thawing approach to form the physical crosslinking with starch-based macromolecules. Both ways of blending and grafting were employed to compound the starch-based macromolecules and poly(vinyl alcohol) (PVA) with good biocompatibility and mechanical properties, so as to prepare the hydrogel. Then, the hydrogel was used as the matrix to synthesize polymer-based hydroxylapatite composites by using the alternate soaking process which is facile and fast in forming hydroxylapatite. In addition, the influence of the hydrogels prepared at different reaction conditions on the contents of hydroxylapatite in the as-prepared composites was studied. The chemical methods used to prepare the esterified product starting from hydroxylapatite (HA) and esterified starch (SM) were researched. The main conclusions were obtained:(1) Different contents of SM influencing on the swelling properties of SM/PVA hyrdrogels was studied, and it was found that the interactions between the molecules were intensified when the SM was added, leading to the decrease of the crystallinity and increase of the swelling degree. In addition, when the SM was incorporated, the–COOH groups were bought in, resulting in the PH reactive intelligent hydrogel.(2) Based on the the matrix of SM/PVA hydrogel, the SM/PVA/HA composite was produced by using the alternate soaking process. From the WAXD spectra, the HA was determined at the biomimetic process; the TGA results indicated that the different contents of SM influenced on the amount of HA. When the content of SM was increased, the amount of HA grossing in the matrix was increased. From the SEM image, the gels with different contents of SM after the biomimetic process exhibited different morphologies. Furthermore, the impact of the cycling number of alternate soaking on the amount of as-prepared HA was researched, and the amount of HA was increased with the cycling number.(3) The esterified starch-grafting PVA (SM-g-PVA) copolymer which was also intelligent hydrogel with PH reactive property was prepared. Additionally, the influence of grafting rates on the swelling behavior was studied, and the results indicated that the swelling behavior was related to the grafting rates.(4) Based on the SM-g-PVA hydrogel matrix, the SM-g-PVA/HA was prepared by using the the alternate soaking method. The characterization methods of FT-IR,WAXD,TGA,EDS were employed to demonstrate that the HA grew in or on the hydrogel in the alternate soaking process. The different grafting rates influencing on the amount of HA produced was also researched.(5) Chemical methods were used to initially research the esterization reaction between HA and SM, and FT-IR,TGA,XRD, etc., were used to determine that only a fraction of HA and SM conduced the esterization reaction.