Responsive coatings

Fig. 5 Smart UV-responsive coating on silica nanoparticles with PNIPAM brushes functionalized with FRET donors, 4-(2-acryloyloxyethylamino)-7-nitro-2,l,3-benzoxadiazole (NBDAE), and photoswitchable acceptors, l -(2-methacryloxyethyl)-3, 3 -dimethyl-6-nitro-spiro(2//-l-benzo-pyran-2,2 -indoline) (SPMA). The UV radiation induces the change from colorless spiropyran derivatives in the outer part of the coating (7) to the fluorescent merocyanine form (2). Thus, FRET with the benzoxadiazole moieties in the inner part of the coating is enabled and the fluorescence color changes from green to red. By variation of the temperature and induction of a collapse of the PNIPAM chains (3), the FRET efficiency can be tuned (4). Reprinted, with permission, from [70], Copyright (2009) American Chemical Society...

In addition to the assessment of pore sizes and quality control, AFM provides direct access to the dynamic changes of smart pores, for instance pores that are equipped with a stimulus-responsive coating. Iwata et al. reported on the pH control of pore opening and closing of poly (acrylic acid) (PAA) -functionalized pores, as shown in Fig. 3.83. [174] The pores of two different membranes are closed, as seen by CM-AFM, at high pH due to the deprotonation of the PAA coating and concomitant expansion of the polymeric layer into the opening of the pore. 

Nitschke M, Gotze T, Gramm S et al (2007b) Detachment of human endothelial cell sheets Irom thermo-responsive poly(NiPAAm-co-DEGMA) carriers. Express Polym Lett 1 660-666 Pan YV, Wesley RA, Luginbuhl R et al (2001) Plasma polymerized N-isopropylacrylamide synthesis and characterization of a smart thermally responsive coating. Biomacromolecules 2 32-36... 

Owing to their high sensitivity toward mass changes, magnetoelastic sensors have been used for the detection of bacteria/viruses and biotoxins. In most cases, biological responsive coatings are apphed on the sensors to convert biological information to mass or elasticity variations. 

Responsive Coating Technology. Plasma Spray Coatings. plasma-spray-coatings/> 2014. 

This chapter provides an overview of the general frame and the constraints of microcapsules in textiles, and exemplifies promising routes for smart (responsive) coatings, laminates and other end-uses. 

Following to this strategy, Hatakeyama, Kikuchi, Yamato, and Okano (2006) prepared carboxyl-functionalised thermo-responsive coatings on tissue culture polystyrene by electron beam-induced copolymerisation of A-isopropylacrylamide and 2-carboxy-isopropylacrylamide. The subsequent co-immobilization of RODS, a cell adhesive peptide, and insulin was found to promote initial cell adhesion and growth while the cultured tissue monolayers still detach spontaneously upon temperature decrease. 

Another route towards biomolecular functionalisation of switchable cell culture carriers was proposed by Gramm et al. (2011). The thermo-responsive polymer poly (vinyl methyl ether) was blended with a small amount of the alternating copolymer of vinyl methyl ether and maleic anhydride. After electron beam cross-linking, stable films with a dry thickness of up to 70 nm were obtained. The introduced anhydride moieties allow for subsequent protein or peptide immobilization without toxic coupling agents. This concept was applied and further developed by Teich-mann et al. (2013). The impact of different adhesion-promoting molecules immobilised in different concentrations to the thermo-responsive coating was evaluated and compared. 

Gramm, S., Teichmann, J., Nitschke, M., Gohs, U., Eichhom, K.-J., Wemer, C. (2011). Electron beam immobilization of functionalized poly(vinyl methyl ether) thin hhns on polymer surfaces - towards stimuli responsive coatings for biomedical purposes. Express Polymer Letters, 5, 970-976. 

Pan Y.V., Wesley R.A., Luginbuhi R., Dento D.D. and Ratner B.D. (2001), Plasma polymerized N-isopropylacrylamide Synthesis and characterization of a smart thermally responsive coating. Biomacromolecules, 2 pp. 32-36. 

There are several proposed mechanisms for the corrosion inhibiting behaviour observed for polypyrrole. One mechanism proposed in the literature is the release of a corrosion inhibiting counter ion from the polypyrrole as it is reduced from its oxidised state to its neutral state by the electrons produced by the oxidation of the metal substrate. This mechanism can be thought of as a smart or responsive coating... 

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