Thermal-Recoverable Tough Hydrogels Enhanced by Porphyrin Decorated Graphene Oxide

Artificial tissue materials usually suffer properties and structure loss over time. As a usual strategy, a new substitution is required to replace the worn one to maintain the functions. Although several approaches have been developed to restore the mechanical properties of hydrogels, they require direct heating or touching, which cannot be processed within the body. In this manuscript, a photothermal method was developed to restore the mechanical properties of the tough hydrogels by using near infrared (NIR) laser irradiation. By adding the porphyrin decorated graphene oxide (PGO) as the nanoreinforcer and photothermal agent into carrageenan/polyacrylamide double network hydrogels (PDN), the compressive strength of the PDN was greatly improved by 104%. Under a short time of NIR laser irradiation, the PGO effectively converts light energy to thermal energy to heat the PDN hydrogels. The damaged carrageenan network was rebuilt, and a 90% compressive strength recovery was achieved. The PGO not only significantly improves the mechanical performance of PDN, but also restores the compressive property of PDN via a photothermal method. These tough hydrogels with superior photothermal recovery may work as promising substitutes for load-bearing tissues.

Research of Solid Materials Thermal Conductivity Measurement Based on Laser Photothermal Method

Thermal conductivity is one of the basic thermal physical parameters of solid materials. In order to research the thermal conductivity of solid materials in low temperature, the paper has built the calculation model of the thermal conductivity, and the functional relation between the laser frequency and phase lag has been simulated. The simulation results are in line with the experimental data. The research indicates that solid thermal conductivity can be measured availably by Laser photothermal method. Numerical simulation of solid thermal conductivity at low temperature shows that solid thermal conductivity changes remarkably when the scope of temperature is from 20k to 80k, however, the change is light from 80k to 300k.