Light-Responsive Hybrids Based on Carbon Nanotubes with Covalently Attached PHEMA-g-PCL Brushes

Abstract

Carbon nanotube (CNT)-based materials allow for the direct conversion of light into heat and then into mechanical force in the so-called photo-mechanical effect. This effect has been observed almost solely in the form of polymer (nano)­composites, where CNTs act as active fillers. To overcome the issue with heterogeneous distribution, hybrids based on multiwalled carbon nanotubes (MWCNTs) covalently modified with poly­(2-hydroxyethyl methacrylate)-graft-poly­(ε-caprolactone) brushes (MWCNTs-PHEMA-g-PCL) were prepared, and their photo-mechanical actuator behavior, without the need for mixing with an elastomer, was proven. The MWCNTs-PHEMA-g-PCL hybrids were synthesized using the surface-initiated reversible addition–fragmentation chain transfer polymerization of 2-hydroxyethyl methacrylate, with subsequent ring-opening polymerization of ε-caprolactone from the pendant hydroxyl groups of PHEMA. It was found that the MWCNTs-PHEMA-g-PCL hybrid material containing 24 wt % MWCNTs possesses the properties of thermoplastic elastomers, while retaining their elastic properties at least up to 100 °C. It exhibits an excellent, fully reversible, repeatable, and fast photo-mechanical actuation behavior.

From Brush to Dendritic Structure: Tool for Tunable Interfacial Compatibility between the Iron-Based Particles and Silicone Oil in Magnetorheological Fluids

“…Smart systems are usually hybrid composites or integrated systems of advanced materials that can respond to external physical or chemical stimuli in a controlled manner to perform specified tasks. , They react to environmental changes, such as mechanical stress and strain, hydrostatic pressure, magnetic − and electric field, − temperature, − light, − pH, and moisture, and then come back to the original state after removing the stimuli. , External stimuli can cause different responses such as changes in size, color, moisture, and viscosity of flow . Smart materials, due to their intelligent behavior toward the alteration of the above-mentioned parameters can be utilized as sensors, actuators, and drug delivery systems .…”