Study On Preparation And Properties Of Double-Network Hydrogels With High Mechanical Strength

Hydrogels, as a new type of polymer material, exhibit tremendous application in the fields of industry, agriculture, biology and material. But the poor mechanical properties of traditional hydrogels largely limited their applications. Therefore it is significant to prepare high mechanical strength hydrogels. In this work, three high mechanical strength double-network hydrogels have been synthesized with different chemicals and methods:(1) Strong hydrogels consisting of PVA and PEG were developed by a simple combination of freeze-thawing technique and high energy beam irradiation. The effects of molecule weight of PEG, ratio of PVA: PEG, thawing temperature and number of freeze-thawing cycles were investigated. The results show that the tensile strength of PVA/PEG hydrogel could achieve 746 kPa, when the molecule weight of PEG was 4000, the ratio of PVA: PEG was 10:4, the thawing temperature was 30℃ and the number of freeze-thawing cycles was 3.(2) A novel tough composite hydrogel was prepared from inorganic bentonite(IB), polyvinyl alcohol(PVA) and polyethylene glycol(PEG) by the freeze-thaw technique. The effects of different concentration of IB(CIB) on the mechanical properties of hydrogels were investigated. The highest tensile stress of hydrogels was achieved(1.1 MPa) when CIB was 5%(w/v).The friction coefficient of hydrogels was decrease with the increasing of CIB.(3) A PVA/PAAm hybrid double-network hydrogel was synthesized via a simple one-pot two-step polymerization method combined UV irradiation and freezing-thawing technology. Results demonstrate that the mechanical strength of PVA/PAAm hybrid double-network hydrogel was highly enhanced(428 k Pa) and also possessed self-healing performance.