Synthesis And Performance Of Microgel Regulation On Hydrogel

Due to the integrated mimic nature of liquid and solid, hydrogels, peculiar promising soft materials have been applied widely in industry, agriculture and biomedical engineering. Hydrogels generally possessed geometry and strength can keep a dynamic balance of matter, heat and moisture transfer in the environment. Microgels with dimensions in the colloidal range have been known for its high specific surface area and absorbent rate. Possible applications of microgels include sensor, microchannel element, and drug delivery and so on. However, the intrinsic disadvantages of hydrogels(poor mechanical strength and slow responsive rate) limit their utilization. Also for microgels it is not appreciated being used in a macro application. Composite hydrogels combined with particles and matrix can acquire enhanced performance and new functions due to a synergistic effect. In this paper, a series of microgels with different properties were firstly prepared, and were subsequently used as initiator and crosslinker to fabricate microgel composite hydrogels with high mechanical strength and rapid responsive rate. Detailed contents are listed as follows:1. Polymer microspheres were self-assembled through the hydrophobic association between polymer chains without crosslinking agent emulsion polymerization mechanism as a reference. Due to the internal structure without chemical crosslinking, polymer microspheres were different structure and form under the different temperatures. We got the different particle size of microspheres by changing the proportion of monomer preparation, and the temperature sensitivity were investigated.2. To improve slow response rate and poor toughness of microsphere composite hydrogel(MCH), the MCH gels were prepared by grafting Polyacrylamide chains onto the surface of thermo-sensitive polymer microspheres in the absence of crosslinking agent. Herein, polymer microspheres without chemical cross-linking structure were obtained by assembly of amphiphilic thermo-sensitive graft copolymer and employed as cross-linking junctions. MCH gels owns excellent toughness(strain at break: 2400%, fracture energy: 80 k Pa) and can adjust the mechanical properties according to temperature stimuli. Moreover, the results of investigation suggest that MCH gels exhibits thermo-sensitive property and their response rate were 5 to 10 times faster than the traditional poly(N- isopropyl acrylamide) organic gel.3. We made the uniaxial tensile experiment and fond that strain hardening phenomena happened on the MCH gels under large deformation. Self-reinforcement behaviors happened in MCH gels with high stretching rate and water content of MCH gels after large-deformation.