Multilayer polymer assemblies

An alternative to grafted PNIPAAm surfaces, which requires previous activation of the supporting substrate, is offered by multilayer polymer assemblies, such as chitosan-grafted-PNIPAAm and alginate multilayered films (Martins et a/., 2011). The layer-by-layer approach allows mild conditions for fabrication and precise control over the thickness of the coatings, which is a relevant issue for modulating cellular adhesiveness. 

In 1997, Decher reported a fundamental concept regarding the multilayer nanoassemblies composed of polycations and polyanions [24]. The polymer assemblies were prepared by an alternate adsorption process, as shown in Figure 6.5. If a substrate has an anionic charge on its surface then polycation could adsorb onto the surface as a first layer. Polyanion could subsequently adsorb onto the surface by immersing in a... 

Surface science has been one of the first beneficiaries of self-assembled nanostructures (in the form of SAMs). Self-assembly is a very general strategy for forming molecularly tailored interfaces, and, other than the few systems that have formed the basis for the majority of work in SAMs, almost none of the obvious opportunities to use self-assembly to build ordered, nanostructured interfaces have been examined. The preparation of more sophisticated structures based on molecules with complex stmctures, on self-assembled colloids, on multilayered polymers formed by electrostatic interactions between charged groups166,167, or on biologically derived structures is just beginning168-171. 

Similar strategies have been followed to obtain white emission from fluorescent polymer systems and phosphorescent ones as well. However, polymer blends have generally been used to fabricated WPLEDs (as multilayer spin-coated polymer assemblies are difficult to obtain owing to close solubility parameters of materials), such as red, green, blue light-emitting three-polymer systems [257-259] and two-... 

A key application for these materials involves the creation of electrostatic superlattices by layer-by-layer assembly [135-138]. The technique involves the sequential adsorption of polycationic and polyanionic monolayers from aqueous solutions to form nanoscale multilayer polymer films of controlled thickness. Such film architectures can be manipulated to achieve unique physical properties, and orchestrated for the construction of a range of devices. For example, well-characterized organic/organo-metallic polymer electrostatic superlattices have been prepared by alternate adsorp-... 

Figure 1. Absorbance at 630 nm versus number of deposited bilayers for polyaniline multilayer films assembled widi six different polymers polyacrylamide (PAAm), polyvinyl pyrrolidone (PVP), jwlyvinyl alcohol (PVA), polyethylene oxide (PEO) and polystyrene sulfonic acid (SPS).

An alternative approach to functionaUzed CNTs is direct surface functionalization of CNTs with reactive groups. For example, Theato and coworkers used partly oxidized multiwall CNTs to install PFP esters on the surface, which could be used for further surface functionaUzation or for use in the reactive LbL assembly of multilayer polymer films. It is worth noting that the obtained thin films were transparent and conductive, making them suitable candidates for solution-processed transparent electrodes [209]. 

Such, G.K.,Johnston, A.P.R., Caruso, E, 2011. Engineered hydrogen-bonded polymer multilayers from assembly to biomedical appUcations. Chem. Soc. Rev. 40,19. 

Such GK, Johnston APR, Caiuso F (2011) Engineered hydrogen-bonded polymer multilayers lium assembly to biomedical applications. Chem Soc Rev 40 19-29... 

Mono- and Multilayers of Spherical Polymer Particles Prepared by Langmuir-Blodgett and Self-Assembly Techniques... 

Electrophoresis measurements provide a qualitative indication of the assembly of polymer multilayers on colloids [49,50], The -potential as a function of polyelectrolyte layer number for negatively charged polystyrene (PS) particles coated with poly(diallyldimethylam-monium chloride) (PDADMAC) and poly(styrenesulfonate) (PSS) are displayed in Figure... 

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