Stimuli-responsive gels

Fig. 11 Influence of temperature and polymer concentration c on the structure of PVME as example of a stimuli-responsive gel...

Disposable autonomous pumps do not require hydrogels with volume phase transition behaviour. Here, the strong swelling superabsorbers can be used, which are mostly more powerful than stimuli-responsive gels. 

Gels are cross-linked networks of polymers immersed in a fluid medium. It is now well known that they can exhibit large volume changes in response to many different stimuli temperature, solvent composition, pH, electric fields. The universality of this volume phase transition of gels has now been clearly established. These stimuli-responsive gels have opened a new field of research by generating numerous experimental and theoretical works they also pave the way for a variety of new technologies (/). 

We first outline the thermodynamic theory of stimuli responsive gels ( ). The free energy is given as a sum of contributions due to the mixing of the solvent and polymer matrix, its elasticity and the presence of counter ions... 

The applications of hydrogels formed by wormlike micelles are still in development however, it may be expected, after extensive testing of their cytotoxicity, that they could be used as artificial extracellular matrices [167]. Stimuli-responsive gels that can assemble and disassemble on demand when an external trigger is applied (e.g., change in temperature) are particularly interesting because... 

Kim H-J, Lee J-H, Lee M (2005) Stimuli-responsive gels from reversible coordination polymers. Angew Chem Int Ed 44 5810-5814. doi 10.1002/anie.200501270... 

This section is focused on pH- and temperature-responsive cationic polymers forming hydrogels. In addition, some dual-stimuli-responsive gels will also be discussed because of their high potential in the biomedical field. 

One of the recent topics in this area involves stimuli-responsive gels, under the descriptive title of self-walking gels, wormlike motion of gels, and peristaltic motion of gels. ... 

Stimuli-Responsive Gels from T-Shaped Molecules... 

Drug Delivery Control by Physical Stimuli-Responsive Gels... 

Systems that control both time and amounts of drug to be delivered by external stimuli are extremely useful in avoiding rejection by the body, developing intelligent drugs, and for various other pharmacological uses. The DOS that controls material transport by stimuli-responsive gels was... 

Fixation of biocatalysts using natural and synthetic polymer gels has been extensively studied, to the point that developing focus is necessary here. In this section, unique gel substrates such superfine poly(vinyl alcohol) (PVA) gels and stimuli responsive gels will be described with respect to fixation while we will also take advantage of the substrates characteristics. 

When a stimuli-responsive gel is used for various devices, the response time is an essential property. The response time of gels is proportional to the square of the gel size [50]. Hence, the possibility of manufacturing as small a gel as possible is an important consideration. A monodisperse microsphere is such an example. The PNIPAAm, which is polymerized by precipitation polymerization, has a 0.94-pm diameter [51 ]. The PNIPAAm microsphere polymerized inside a micelle is 80-150 nm in diameter and its response time is excellent [52]. 

Photochromism dyes, 226-7 Photocrosslinking, 42-3, 123 Photoelectric conversion efficiency, 310 Photoinduced electricity, 310 Photoresponsive gels, 248 Photosensitive print materials, 386 PHPeEG, 231 Physical stimuli, 369-70 Physical stimuli-responsive gels, drug delivery control, 74-6 Piezochromism, 225 Piezoelectricity, 309-10 Pigment sedimentation, 386 Platinum, 252, 290, 293, 294 PMAA, 242, 243... 

One of the excellent properties of polymer gels is that they can swell and shrink in response to changes in the environment (stimuli-responsive gels). This phenomenon was first reported experimentally by Tanaka [12]. 

The abundant energy in the desert and drylands is solar, which can be used as a source of heat and electrical energy. It may be possible to utilize such unused resources to recycle water. Stimuli-responsive gels are one of the materials that may have the potential to achieve this goal. Study of these materials has increased in recent years. 

There are many natural hydrogels such as konnyaku, agar, and kamaboko. As polymer chemistry develops, synthetic polymer gels are increasingly used for separation, and as medical materials and sealants. However, these gels do not respond to external stimuli. Since the discovery and theoretical development of the volumetric phase transition by Tanaka (MIT) [9] many stimuli-responsive gels have been synthesized and their stimuli responsive behavior has been studied. 

Stimuli-Responsive Gels Based on Ring-Opened Polyferrocenes Synthesis, Characterization, and Electrochemical Studies of Swellable, Thermally Cross-Linked Polyferrocenylsilanes... 

Recently, we reported the first examples of well-characterized, crosslinked, swellable polyferrocenylsilanes (7). Thermal copolymerization of ferrocenophane 1 with the spirocyclic [IJferrocenophane 3 allows access to material with controlled crosslink densities. Because of the interesting properties of polyferrocenylsilanes, we identified crosslinked examples as possible candidates for stimuli-responsive gels. 

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