Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

Shape-memory polymers

Polymer nanocomposites based on functionalized carbon nanotubes

Shape-memory polymers and their composites: Stimulus methods and applications

Summary: Electro-active shape-memory composites were synthesized using conducting polyurethane (PU) composites and multi-walled carbon nanotubes (MWNTs) Surface modification of the MWNTs (by acid treatment) improved the mechanical properties of the composites The modulus and stress at 100% elongation increased with increasing surface-modified MWNT content, while elongation at break decreased MWNT surface modification also resulted in a decrease in the electrical conductivity of the composites, however, as the surface modified MWNT content increased the conductivity increased (an order of 10−3 S · cm−1 was obtained in samples with 5 wt-% modified-MWNT content) Electro-active shape recovery was observed for the surface-modified MWNT composites with an energy conversion efficiency of 104% Hence, PU-MWNT composites may prove promising candidates for use as smart actuators

The electro-active shape-recovery behavior of PU-MWNT composites The pictured transition occurs within 10 s when a constant voltage of 40 V is applied

Electroactive Shape‐Memory Polyurethane Composites Incorporating Carbon Nanotubes

In this paper we are concerned with the design, manufacture and performance test of a lightweight piezo-composite curved actuator (called LIPCA) using a top carbon fiber composite layer with near-zero coefficient of thermal expansion (CTE), a middle PZT ceramic wafer, and a bottom glass/epoxy layer with a high CTE. The main point of the design for LIPCA is to replace the heavy metal layers of THUNDER™ by lightweight fiber reinforced plastic layers without losing the capabilities for generating high force and large displacement. It is possible to save up to about 40% of the weight if we replace the metallic backing material by the light fiber composite layer. We can also have design flexibility by selecting the fiber direction and the size of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use an epoxy resin prepreg system. Glass/epoxy prepregs, a ceramic wafer with electrode surfaces, and a carbon prepreg were simply stacked and cured at an elevated temperature (177 °C) after following an autoclave bagging process. We found that the manufactured composite laminate device had a sufficient curvature after being detached from a flat mould. An analysis method using the classical lamination theory is presented to predict the curvature of LIPCA after curing at an elevated temperature. The predicted curvatures are in quite good agreement with the experimental values. In order to investigate the merits of LIPCA, performance tests of both LIPCA and THUNDER™ have been conducted under the same boundary conditions. From the experimental actuation tests, it was observed that the developed actuator could generate larger actuation displacement than THUNDER™.

Design and manufacture of a lightweight piezo-composite curved actuator

This paper describes an analytical design model for a layered piezo-composite unimorph actuator and its numerical and experimental verification using a LIPCA (lightweight piezo-composite curved actuator) that is lighter than other conventional piezo-composite type actuators. The LIPCA is composed of top fiber composite layers with high modulus and low CTE (coefficient of thermal expansion), a middle PZT ceramic wafer, and base layers with low modulus and high CTE. The advantages of the LIPCA design are to replace the heavy metal layer of THUNDER by lightweight fiber-reinforced plastic layers without compromising the generation of high force and large displacement and to have design flexibility by selecting the fiber direction and the number of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use a resin prepreg system. A piezo-actuation model for a laminate with piezo-electric material layers and fiber composite layers is proposed to predict the curvature and residual stress of the LIPCA. To predict the actuation displacement of the LIPCA with curvature, a finite element analysis method using the proposed piezo-actuation model is introduced. The predicted deformations are in good agreement with the experimental ones.

Analytical design model for a piezo-composite unimorph actuator and its verification using lightweight piezo-composite curved actuators

Effect of an Artificial Caudal Fin on the Performance of a Biomimetic Fish Robot Propelled by Piezoelectric Actuators

Electroactive shape memory composites were prepared using polyurethane block copolymer and conducting polypyrrole by chemical oxidative polymerization. The electrical conductivity, thermal and mechanical properties, and morphology of the composites were investigated, and a voltage-triggered shape memory effect was demonstrated. The polyurethane synthesized had a transition temperature near 46 °C. The presence of polypyrrole increased the conductivity of the composites, and a high conductivity of the order of 10 -2 S/cm was obtained at 6-20 wt.-% polypyrrole. Such a conductivity of composites was enough to show electroactive shape recovery by heating above the transition temperature of 40-45 °C due to melting of the polycaprolactone soft segment domain. Thus a good shape recovery of 85-90% could be obtained in the shape recovery test with bending mode when an electric field of 40 V was applied.

Nam Seo Goo

Papers

Electroactive Shape‐Memory Polyurethane Composites Incorporating Carbon Nanotubes

Design and manufacture of a lightweight piezo-composite curved actuator

Analytical design model for a piezo-composite unimorph actuator and its verification using lightweight piezo-composite curved actuators

Effect of an Artificial Caudal Fin on the Performance of a Biomimetic Fish Robot Propelled by Piezoelectric Actuators

Conducting Shape Memory Polyurethane‐Polypyrrole Composites for an Electroactive Actuator