Self-healing,Stretchable,Temperature-Sensitive and Strain-Sensitive Hydrogel-based Flexible Sensors

Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical applications,such as the damage caused by external effects,leading to equipment failure,and the inability to perceive ambient temperature,resulting in single functionality.Herein,a stretchable,self-healing and dual temperature-strain sensitive hydrogel,with a physically-crosslinked network,is designed by constructing multiple dynamic reversible bonds.Graphene oxide(GO)and iron ions(Fe^(3+))act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding,rendering excellent stretchability to the hydrogel.The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties.Moreover,the incorporated N-isopropyl acrylamide(NIPAM)provides excellent temperature responsiveness to the hydrogel,facilitating the detection of external temperature changes.Meanwhile,the hydrogels exhibited strain-sensitivity,with a wide working range of 1%-300%,fast response and electrical stability,which can be used as flexible sensors to monitor body motions,e.g.,speaking and the bending of finger,wrist,elbow and knee.Overall,the hydrogel possesses dual sensory capabilities,combining external temperature and strain,for potential applications in wearable multifunctional sensing devices.

Use of HPHT Autoclave to Determine Corrosion Inhibition Effect of Poly(methyl methacrylate-co-N-vinyl-2-pyrrolidone) on Carbon Steels in 3.5% NaCl Solution Saturated with CO_2

The influence of poly（methylmethacrylate-co-N-vinyl-2-pyrrolidone）, P（MMA-co-VP）, on corrosion of carbon steels（J55, N80, P110 SS and C110 steels） in 3.5 wt% NaCl solution saturated with CO2 was evaluated using static high pressure and high temperature（HPHT） autoclave. The surface was further evaluated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and contact angle measurements. Quantum chemical calculations have been used to evaluate the structural, electronic and reactivity parameters of the inhibitor on the steels surface. SEM, XRD and contact angle measurement studies reveal that the surface of metals are quite unaffected after use of inhibitor in 3.5% NaCl solution saturated with CO2.