Responsive materials

Poly[(4-carboxylatophenoxy)(methoxyethoxyethoxy)phosphazene] copolymers of variable compositions were synthesized by Allcock [645] in 1996. These polymers were found to be soluble in alkaline solutions. When crosslinked (by y-rays or by addition of CaCl2 to the polymer solution) the resulting hydrogels were found able to contract or expand as a function of the pH of the solution and their utilization as pH-responsive materials for drug delivery systems could be envisaged. 

In the previous sections it was demonstrated that the stimulus-responsive behavior of ELP was transferred to ELP fusion proteins and even to non-covalently bound moieties, such as proteins, plasmids, and heavy metals, mostly for biomedical and biotechnological applications. The ability of ELPs to reversibly switch their polarity is also of great interest for the development of stimulus-responsive materials. Many approaches have therefore recently been undertaken to integrate ELPs with, for example, polymers, particles, and surfaces. 

Stimuli-responsive materials, shape-memory polymers as, 22 355-356 Stirling cycle, 8 43 Stirred autoclave, 14 89, 92t Stirred autoclave reactor, 20 216 Stirred batch RO unit, 21 644 Stirred mills, 16 615 Stirred tank bioreactors, 1 737-740 oxygen transfer driving force, 1 734 Stirred tank electrochemical reactor (STER), 9 660-662... 

In a more general way, the two major driving forces for the design of novel micellar systems are the control over morphology (spheres, vesicles, rods, tubules etc. with controlled size) and function (stimulus-responsive materials, biological functions). Both of these aspects are intimately related since a given morphology can induce a specific function. 

The original inventory file has grown into a wide ranging data-base with utility for emergency response, Material Safety Data Sheet information and is the cornerstone for Monsanto s Occupational Exposure and Medical Systems. Therefore, the original centralized effort has borne considerable fruit in addition to and independent of the TSCA inventory. 

Many biological polymers display a cooperative transition from an ordered to disordered state [34] including the helix coil transitions observed for both peptides [35] and nucleic acids [36]. Synthetic systems that are able to undergo a cooperative helix coil transition can complement biopolymer studies and are of potential interest for density-responsive materials. 

In this chapter we will focus on side chain functionalized supramolecular polymers as well as main chain noncovalent functionalized polymers, which are the two main areas of supramolecular polymers. We will initially discuss the design principles and methodology of side chain functionalization, in particular, multifunctionalization. In the later part of the chapter, we will discuss in detail two important applications of side chain functionalized supramolecular polymers. The first application involves the use of noncovalent interactions to yield highly functionalized materials, whereas the second application involves the reversible noncovalent cross-linking of polymers to yield responsive materials. 

Polythiophenes functionalized with monosaccharides have been evaluated for their ability to detect the influenza virus and E. coli (Baek et al. 2000). Copolymers of thiophene acetic acid 10 and carbohydrate-modified thiophenes 11 have been prepared via iron(III) chloride mediated polymerization. Addition of influenza virus to a sialic acid containing copolymer resulted in a blue shift of the polymer absorption maximum, resulting in an orange to red chromatic transition. Mannose-containing polythiophenes underwent color changes upon the addition of the lectin ConA or E. coli cells that contain cell surface mannose-binding receptors. A similar biotinylated pol5hhiophene afforded a streptavidin responsive material (Paid and Leclerc 1996). 

Ulijn RV (2006) Enzyme responsive materials a new class of smart biomaterials. J Mat Chem 16 2217-2225... 

For the over-the-counter formulations, two of the thirty-nine items tested contained TEA responsive materials. For these tvo instances, exposure of the organic extracts to glacial acetic acid alone led to the complete disappearance of the TEA responsive materials (34). This observation suggests that the unknown materials are probably not simple N-nitroso derivations, and the results are more compatible with their being O-nitroso compounds (nitrites) (34h... 

In those instances where TEA responsive materials were present, the levels were in the low ppb range (40-81 ppb). Should any of these materials be confirmed as real N-nitroso compounds, and if these are known or suspected carcinogens, then there may be a health risk for persons taking them. However, it must be emphasized that we have no evidence at present with regard to the carcinogenic risk of any of the drug product impurities indicated in Table 1. 

We are optimistic that the field of semiconductor photochemistry will lead to new materials, devices, and techniques to solve many important problems facing our society, including development of renewable energy sources, methods for environmental remediation, and advanced sensor and monitoring technologies. The chapters herein are up-to-date, comprehensive, and authoritative. The book is a valuable resource for both students and scientists working in the broad area of optically responsive materials based on nanostructured semiconductors. 

Nevertheless, the characteristic time constant is roughly proportional to the square of the typical size and to the inverse of collective diffusion coefficient D which is given by the modulus divided by the friction. The porous structures presented here are one of the solutions to achieve a high response material. 

FI.UOROMETERS. In fluorescence analysis, the amount of light emitted characteristically under suitable excitation is used as u measure of the concentration of the responsible material under observation. Thus, the method is clusely related to colorimetric or spectrophotometric analysis, in which the amount of light absorbed characteristically is used to measure the concentration of the dissolved species. 

Abstract We describe mechanochromic and thermochromic photoluminescent liquid crystals. In particular, mechanochromic photoluminescent liquid crystals found recently, which are new stimuli-responsive materials are reported. For example, photoluminescent liquid crystals having bulky dendritic moieties with long alkyl chains change their photoluminescent colors by mechanical stimuli associated with isothermal phase transitions. The photoluminescent properties of molecular assemblies depend on their assembled structures. Therefore, controlling the structures of molecular assemblies with external stimuli leads to the development of stimuli-responsive luminescent materials. Mechanochromic photoluminescent properties are also observed for a photoluminescent metallomesogen and a liquid-crystalline polymer. We also show thermochromic photoluminescent liquid crystals based on origo-(/ -phenylenevinylene) and anthracene moieties and a thermochromic photoluminescent metallocomplex. 

Urban MW (ed) (2011) Handbook of stimuli-responsive materials. Wiley-VCH, Weinheim... 

Y. Zhao, Smart Light-Responsive Materials, Wiley-Blackwell, Indianapolis 2009 Ch. Dugave (ed.), cis-trans Isomerisation in Biochemistry, Wiley-VCH, Weinheim 2006 For photomobile polymer materials and light driven plastic motors, see M. Yamada, Y. Yu, M. Kinoshita, C.J. Barret,... 

The current trend towards miniaturization of functional systems and devices has driven the study of confinement effects (finite film thickness and the nature of the binding interfaces) on the fundamental physical properties of soft materials. Rapid developments of novel sensor and lab-on-chip technologies, and of polymer-based stimuli-responsive materials, raise the question of changes in solvent-polymer interactions under confinement. 

But the day of dumb buildings is on its way out, just as is the day of dumb cars, dumb airplanes, dumb weapons, dumb satellites, and just about any other kind of dumb structure you can imagine. The day of smart structures built with smart materials has just about arrived in the developed world. Smart materials have been defined as materials that respond to environmental stimuli by making some change in their physical characteristics, such as their size, shape, electrical or magnetic conductivity, or optical properties. Because they respond to change in the surrounding environment, smart materials are also sometimes called responsive materials. 

In the broadest sense, all materials are smart materials because they all change in at least some way when exposed to changes in their environment. For example, the volume of any material changes when the temperature around it changes. In the vast majority of cases, the volume of the material increases as the temperature increases. This principle lies at the basis of at least one familiar appliance in your home that uses responsive materials a thermostat. A thermostat is a metal strip consisting of two metals bonded to each other. The two metals expand at different rates when they are heated. Since they expand at different rates, the strip bends in one direction or another as the temperature changes. As it bends, the strip either comes into contact with a metal electrode and closes a circuit, or it moves away from that contact and stops the flow of current through the circuit. 

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