Abstract
Nanoparticles have leading strengthening and toughening effects on polymer matrix. Anisotropic Janus nanoparticles exhibit abundant interfacial behavior because their two surfaces possess different chemical properties. Herein, Janus nanosheets (JNSs) were synthesized by one-pot method. Different surficial morphology and chemical groups on each surface of JNSs were observed by SEM and AFM. In the process of tannic acid/polyacrylic acid (TA/PAA) polymerization, JNSs act as crosslinking agent to promote the formation of nanocomposite double network hydrogels. When the TA/PAA hydrogels were stretched, both strength and toughness of TA/PAA hydrogels are improved owing to the solid silica enhancement, the orientation-disorientation and the interfacial chemical bond of JNSs. Besides, adsorption-desorption of PAA molecular chains also toughens hydrogels. The tensile strength and the elongation at break of TA/PAA hydrogels containing 1.5wt% JNSs are 42 KPa and 370.9 %, respectively. Compared with the TA/PAA without JNSs, they increase by 90.9% and 88.7%. The recovery and self-healing of hydrogels with JNSs were accelerated dramatically. Meanwhile, the anti-fatigue property was improved. The as-prepared anisotropic Janus particles synthesized by one-pot method on strengthening and toughening double network hydrogels provide a new idea for the synthesis of Janus nanosheets and the crosslinking of hydrogel.
Protein encapsulation in alginate hydrogel beads: Effect of pH on microgel stability, protein retention and protein release