Preparation And Properties Of PVP-PAMPs/PAAm Ternary Composite Double-network Hydrogel

Hydrogel, as a polymer material with various properties, has been concernedwidely in the last three decades. A variety of products with different composition,structure and properties have been studied and prepared, and have a widelyapplication in production and daily life. However, with further research, poormechanical properties of hydrogels have been gradually exposed, which greatly limitsthe prospects of hydrogels. Thus, the further study of double-network hydrogel isvery significant.In this paper, a two-step dual initiator system was used to preparePAMPs/PAAm double network hydrogels. The impacts of irradiation time, amount ofinitiator and monomer ratio in the preparation of DN hydrogel was studied. The firststep was initiated by UV irradiation, a1M AMPs aqueous solution containing4mol-%crosslinking agent a0.6mol-%initiator, α-ketoglutaric acid was irradiate by50seconds. The second step was initiated using a thermal initiator. The reaction timewas15hours, the amount of initiator KPS is0.1mol-%, the concentration of themonomer AAm is2mol/L. The DN gels prepared by this process sustains acompressive stress of11.28MPa when the compressive strain is90%.In the meantime, PAMPs/PAAm DN hydrogel was modified byPolyvinylpyrrolidone (PVP), PVP-PAMPs/PAAm Ternary CompositeDouble-network Hydrogel (TCDN gel) was prepared by the same process mentionedabove. The mechanical properties, swelling behavior and morphology was measuredto study the impact of PVP in different molecular weight and different content. Theenhanced mechanism was speculated. The results indicates that：PVP in differentmolecular weight (K15：8000、K30：58000、K90：1300000) shows different impactson the TCDN gels network structure.The main influence of K15was to hinder itsregular crosslinked, provides a greater degree of freedom of the PAAm chain. Thecompressive stress decrease while the strain enhanced, no rupture observed afterstains of95%. PVP in K30shows a rigid interpenetrating with the main PAMPsnetwork, forming a new highly cross-linked rigid interpenetrating network structure with two components. This network structure provided an increase in elastic modulusand toughness. PVP in K90provided an extremely high ratio of rigid interpenetrating,cause a high crosslinking density. The free slide of PAAm chain is limited due to thehighly cross-linked network, shows a lower ultimate deformation, cause a lowercompressive strength. TCDN gel prepared with5%,K30PVP exist, shows acompressive stress of30.14MPa at the strain of90%,3times to the DN gels preparedin the same process.Finally, a preliminary study of adsorption and release behavior of the DN geland TCDN gels for the model drug, Rhodamine B (Rh-B) was performed. The resultsindicate that: The introduced of PVP, easily complex with the carboxyl in Rh-B,forming a thermodynamically stable solid complexes, improve the adsorptioncapacity of the TCDN gels. The main factors affecting the release behavior of Rh-Bfor hydrogels is the cross-linked structure and the complexation of PVP and Rh-B.