Shape-memory polymers
TL;DR: Shape-memory polymers as discussed by the authors are an emerging class of active polymers that can change their shape in a predefined way from shape A to shape B when exposed to an appropriate stimulus.
About: This article is published in Materials Today.The article was published on 2007-04-01 and is currently open access. It has received 1575 citations till now. The article focuses on the topics: Shape-memory polymer.
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6,213 citations
TL;DR: The status of graphene research is presented, which includes aspects related to synthesis, characterization, structure, and properties.
Abstract: Every few years, a new material with unique properties emerges and fascinates the scientific community, typical recent examples being high-temperature superconductors and carbon nanotubes. Graphene is the latest sensation with unusual properties, such as half-integer quantum Hall effect and ballistic electron transport. This two-dimensional material which is the parent of all graphitic carbon forms is strictly expected to comprise a single layer, but there is considerable interest in investigating two-layer and few-layer graphenes as well. Synthesis and characterization of graphenes pose challenges, but there has been considerable progress in the last year or so. Herein, we present the status of graphene research which includes aspects related to synthesis, characterization, structure, and properties.
3,513 citations
TL;DR: Shape memory alloys (SMAs) are a class of shape memory materials (SMMs) which have the ability to "memorise" or retain their previous form when subjected to certain stimulus such as thermomechanical or magnetic variations.
2,818 citations
2,750 citations
University of Cambridge1, Istituto Italiano di Tecnologia2, Lancaster University3, University of Manchester4, Catalan Institution for Research and Advanced Studies5, Technical University of Denmark6, Nokia7, fondazione bruno kessler8, University of Trento9, Queen Mary University of London10, Technische Universität München11, Polytechnic University of Milan12, Centre national de la recherche scientifique13, University of Trieste14, University of Ioannina15, University of Geneva16, Trinity College, Dublin17, Texas Instruments18, University of Paris19, Spanish National Research Council20, Leiden University21, Delft University of Technology22, University of Patras23, École Normale Supérieure24, Radboud University Nijmegen25, Nest Labs26, Airbus UK27, Seoul National University28, Yonsei University29, University of Oxford30, Chalmers University of Technology31, University of Groningen32, STMicroelectronics33, Chemnitz University of Technology34, Max Planck Society35, Aalto University36
TL;DR: An overview of the key aspects of graphene and related materials, ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries are provided.
Abstract: We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.
2,560 citations
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TL;DR: New challenges and directions in biomaterials research are discussed, including synthetic replacements for biological tissues, designing materials for specific medical applications, and materials for new applications such as diagnostics and array technologies.
Abstract: Biomaterials have played an enormous role in the success of medical devices and drug delivery systems. We discuss here new challenges and directions in biomaterials research. These include synthetic replacements for biological tissues, designing materials for specific medical applications, and materials for new applications such as diagnostics and array technologies.
2,949 citations
TL;DR: A very broad, additional spectrum of possible applications for intelligent polymers that covers an area from minimally invasive surgery, through high-performance textiles, up to self-repairing plastic components in every kind of transportation vehicles.
Abstract: Shape memory polymer compositions, articles of manufacture thereof, and methods of preparation and use thereof are described. The shape memory polymer compositions can hold more than one shape in memory. Suitable compositions include at least one hard segment and at least one soft segment. The Ttrans of the hard segment is preferably between -30 and 270 °C. At least one of the hard or soft segments can contain a cross-linkable group, and the segments can be linked by formation of an interpenetrating network or a semi-interpenetrating network, or by physical interactions of the blocks. Objects can be formed into a given shape at a temperature above the Ttrans of the hard segment, and cooled to a temperature below the Ttrans of the soft segment. If the object is subsequently formed into a second shape, the object can return to its original shape by heating the object above the Ttrans of the soft segment and below the Ttrans of the hard segment. The compositions can also include two soft segments which are linked via functional groups which are cleaved in response to application of light, electric field, magnetic field or ultrasound. The cleavage of these groups causes the object to return to its original shape.
2,837 citations
TL;DR: A group of degradable thermoplastic polymers that are able to change their shape after an increase in temperature enables bulky implants to be placed in the body through small incisions or to perform complex mechanical deformations automatically.
Abstract: The introduction of biodegradable implant materials as well as minimally invasive surgical procedures in medicine has substantially improved health care within the past few decades. This report describes a group of degradable thermoplastic polymers that are able to change their shape after an increase in temperature. Their shape-memory capability enables bulky implants to be placed in the body through small incisions or to perform complex mechanical deformations automatically. A smart degradable suture was created to illustrate the potential of these shape-memory thermoplastics in biomedical applications.
2,145 citations
TL;DR: Polymers containing cinnamic groups can be deformed and fixed into pre-determined shapes—such as elongated films and tubes, arches or spirals—by ultraviolet light illumination and can recover their original shape at ambient temperatures when exposed to ultraviolet light of a different wavelength.
Abstract: Materials are said to show a shape-memory effect if they can be deformed and fixed into a temporary shape, and recover their original, permanent shape only on exposure to an external stimulus. Shape-memory polymers have received increasing attention because of their scientific and technological significance. In principle, a thermally induced shape-memory effect can be activated by an increase in temperature (also obtained by heating on exposure to an electrical current or light illumination). Several papers have described light-induced changes in the shape of polymers and gels, such as contraction, bending or volume changes. Here we report that polymers containing cinnamic groups can be deformed and fixed into pre-determined shapes--such as (but not exclusively) elongated films and tubes, arches or spirals--by ultraviolet light illumination. These new shapes are stable for long time periods, even when heated to 50 degrees C, and they can recover their original shape at ambient temperatures when exposed to ultraviolet light of a different wavelength. The ability of polymers to form different pre-determined temporary shapes and subsequently recover their original shape at ambient temperatures by remote light activation could lead to a variety of potential medical and other applications.
1,807 citations
TL;DR: In this paper, single-wall carbon nanotubes (SWNTs) were used to augment the thermal transport properties of industrial epoxy composites and showed a 70% increase in thermal conductivity at 40 K, rising to 125% at room temperature; the enhancement due to 1 wt'% loading of vapor grown carbon fibers was three times smaller.
Abstract: Single-wall carbon nanotubes (SWNTs) were used to augment the thermal transport properties of industrial epoxy. Samples loaded with 1 wt % unpurified SWNT material showed a 70% increase in thermal conductivity at 40 K, rising to 125% at room temperature; the enhancement due to 1 wt % loading of vapor grown carbon fibers was three times smaller. Electrical conductivity data showed a percolation threshold between 0.1 and 0.2 wt % SWNT loading. The Vickers hardness rose monotonically with SWNT loading up to a factor of 3.5 at 2 wt %. These results suggest that the thermal and mechanical properties of SWNT-epoxy composites are improved, without the need to chemically functionalize the nanotubes.
1,683 citations