Thermoresponsive materials lower critical solution

SI-IMP has been used for synthesis of different types of stimuli-responsive polymer brushes that are responsive to several external stimuli, such as pFI, temperature, and ionic strength [28,58-65]. Because materials interact with their surroundings via their interfaces, the ability to fashion soft interfacial layers and tune the range, extent, and type of physicochemical interactions across interfaces is central to a variety of applications. Rahane et al. carried out sequential SI-IMP of two monomers to create bilevel poly(methacrylic acid)-Woc/c-poly(N-isopropylacrylamide) (PMAA-b-PNIPAM) block copolymer brushes that can respond to multiple stimuli [28]. They observed that each strata in the bilevel PMAA-b-PNIPAM brush retained its customary responsive characteristics PMAA being a "weak" polyelectrolyte swells as pH is increased and the thermoresponsive PNIPAM block collapses as temperature is raised through the volume phase transition temperature due to its lower critical solution temperature (LCST) behavior. As a result of ions added to make buffer solutions of various pH and because of the effect of surface confinement, the swollen-collapse transition of the PNIPAM layer occurs at a... 

The most popular examples of switchable substrates are the thermosensitive surfaces that change from hydrophobic to hydrophilic substrates upon small temperature changes. Thermoresponsive polymers, which exhibit a lower critical solution temperature (LCST) in water close to body temperature, are the mostly used responsive materials to produce surfaces with tunable cell attachment/detachment (da Silva et /., 2007). 

Abstract This chapter describes polymers that undergo a temperature-induced phase transition in aqueous solution providing an important basis for smart materials. Different types of temperature-responsive polymers, including shape-memory materials, hquid crystalline materials and responsive polymer solutions are briefly introduced. Subsequently this chapter will focus on thermoresponsive polymer solutions. At first, the basic principles of the upper and lower critical temperature polymer phase transitions will be discussed, followed by an overview and discussion of important aspects of various key types of such temperature-responsive polymers. Finally, selected potential apphcations of thermoresponsive polymer solutions will be described. 

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