Examples of Smart Materials

Functionalised conjugated polymers such as polythiophenes were studied from the point of view of the detection and transduction of chemical and physical information into an optical or electrical signal. Their ionochromism (reversible change of colour in the presence of ions), photochromism (reversible change of colour on exposure to light), affinity chromism (tendency to colour change) and electroluminescence of polythiophene complexes with crown ethers and other solutions are discussed in detail [295]. 

The basic polymer principles related to smart polymer flame retardancy and the relationship between flammability and polymer structure are also reviewed [296]. 

Conductive polymers have been produced to develop smart windows by electrodeposition of various high conductivity polymers on transparent conductive substrate. A suspended particle device that enables users to control the passage of light through glass or plastic windows has been commercialised. The specially treated panes can also be used to shield instrumentation. In such systems a polymer film between two panes of glass or plastic is 

An overview on supramolecular polymer chemistry is presented in combination with a discussion of several potential smart systems based on hydrogen bonding and metal-ligand interactions. For a particular system, terpyridine-metal, the switchable properties are discussed in [291]. 

Leterrier and J-A.E. Manson, Polymer Engineering and Science, 

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Supermolecular interlocked macromolecules have been paid much attention as candidates of smart materials. Polyrotaxane (PRX) is a typical example. PEG/ cyclodextrin (CD)-based polyrotaxane was firstly reported by Harada and coworkers by attachment of stoppers to pseudopolyrotaxane (pPRX) consisting of a PEG and CDs [263]. Subsequently, many CD-based PRXs have been designed and prepared as smart materials such as biomaterials, light-harvesting antennae, insulating polymers, stimuli-responsive molecular shuttles etc. [264—268]. 

Abstract Dye-doped polymeric micro- and nanobeads represent smart analytical tools that have become very popular recently. They enable noninvasive contactless sensing and imaging of various analytical parameters on a nanoscale and are also widely employed in composite sensing materials, in suspension arrays, and as labels. This contribution gives an overview of materials and techniques used for preparation of dye-doped polymeric beads. It also provides examples of bead materials and their applications for optical sensing and imaging. 

As with most other types of smart materials, an important impetus for research on SMAs has been their potential applications in the military and aerospace industry. TiNi Aerospace, for example,... 

Self-healing materials form another emerging class of smart materials. Such materials have the ability to recover from damage, such as cracks and holes, by repairing ( healing ) themselves [62]. Some examples of repair mechanism are as... 

In most cases, the as-obtained nanocarriers can release the loaded biomolecules in response to only one kind of external stimulus, such as light, pH, or temperature, and realize a monoresponsive nanochannel. However, the sensitivity of these nanocarriers is not very efficient. Even for NIR-triggered phototherapy, the effective penetration depth of NIR light is still limited to no more than 1 cm and its sensitivity and accuracy to treat tumors located deep inside the body is thus limited. Therefore, delivery systems triggered by at least two different inputs have recently been considered by researchers. Generally, in order to get dual-responsive nanocarriers, two kinds of smart materials or one material with two functional groups must be included in the same NP. For example, two kinds of responsive materials, such as PAA and PNIPAm, can be simultaneously employed in the a pH- and... 

Bob Newnham proposed the idea of smart materials in the 70 . Since that we find research programs focused on systems with embedded actuators, sensors and controller units. Active structures proved beneficial, which for example arises from increased safety, reduced energy consumption, extended life cycle and unique performance. But as a non-series product they failed often by high production costs. In other words, extension of market share of active structures to commercial applications requires technology chains and designs, which are compatible with mass production, like typical found in care manufacturing. 

On the other hand, the study of smart textiles is related to the study of smart materials, while the way those materials should be processed to form a smart textile are considered and researched. Examples of the many different technologies that have to be used to incorporate the smart materials into a textile include sewing, weaving, knitting, braiding, and printing. 

In this chapter we have chosen not to focus on specific examples of smart textiles application in order to avoid narrowing the field of smart implantable fibrous medical devices to a few innovative textile properties. Contrariwise, fiber characteristics are pointed out to show that all of them, in a prospective designing approach, could achieve smart features in the implantable device area. However, we are limited in exploratory areas using new materials because a decline is needed to be certain that a material is accepted by the body. Given the diversity of appreciation of smart appearance, as well as the implantable medical device aspect, we have focused on the biocompatibility and biointegration of substitutes in their environment. This theme therefore needs to be complemented by other approaches such as the concepts of smart attitude and implantable device as related in Fig. 13.1. 

The issue with this type of superimposed layer strategy is that it creates a bulky and heavy protective clothing system, with a negative impact of comfort, ergonomics, and function. The same problem stands with other types of PPE, for example, helmets, boots, etc. On the other hand, if the PPE material or layer can combine several functions and protect against the whole list of hazards associated with a type of activity, for example, through the use of smart materials, gains in comfort and efficiency can be made (Peltonen et al., 2012). 

The last example of application of smart materials to PPE described in this chapter deals with shock absorbers. With shear thickening fluids, complete flexibility is maintained in static conditions while the material instantaneously hardens upon impact at high rate. Products based on elastomer foam and 2D and 3D impregnated fabrics are already on the market, with a particular target at sports, defense, and law enforcement applications. 

Thermoresponsive polymers provide a promising basis for the development of smart materials. In this section, selected recent examples will be discussed to highlight this potential, focusing on the more common LCST polymers. For more comprehensive overviews of the use of thermoresponsive polymers for biomedical applications, the reader is referred to a number of recent review articles (De las Heras Alarcon et al., 2005 Schmaljohann, 2006 Ward and Theoni, 2011). 

There is a host of other applications for alloys displaying this effect—for example, eyeglass frames, tooth-straightening braces, collapsible antennas, greenhouse window openers, antiscald control valves on showers, women s foundation-garments, fire sprinkler valves, and biomedical applications (such as blood-clot filters, self-extending coronary stents, and bone anchors). Shape-memory alloys also fall into the classification of smart materials (Section 1.5) because they sense and respond to environmental (i.e., temperature) changes. 

The implementation of different actuation systems in lab-on-a-chip devices requires smart materials to successfully perform the pumping, mixing, or separation actuation, while assuring an easy integration in the lab-on-a-chip devices. This section will focus on some examples of innovative materials to promote the control of fluids in a lab-on-a-chip PVDF (poly(vinylidene fluoride)), modified chitosan and magnetic particles. 

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