Hybrid polymeric films

By the sol-gel-process, inorganic glassy and hybrid polymeric materials are accessible at comparatively low temperatures [1], Therefore, organic molecules or dyes can easily be incorporated into the oxide matrix. This combination is especially attractive for the development of the following devices optical filters, solid-state lasers, optical switches, nonlinear optical laser hosts, optical data storage media, and photoconductive devices and films [2]. 

Following a related approach, Castelvetro et al. reported the formation and properties of hybrid latex films resulting from the coalescence of low 7 poly(BA-co-MMA-co-MPTMS) terpolymer latex particles coated by a silica shell [78], The latex was synthesized at neutral pH by semi-continuous emulsion polymerization under starved-feed conditions in order to protect the MPTMS monomer from premature hydrolysis and condensation reactions. A substantial amount of free silanols were therefore available for further reaction with the silica precursor. In order to avoid the formation of a densely crosslinked silica network around the latex core, which may significantly alter film formation, the pH was kept at around 2 (at this pH, hydrolysis is promoted and condensation is significantly retarded). TEM and AFM studies of the nanocomposite film indicated that the silica shell formed a continuous percolating network throughout the polymer matrix. A porous film of interconnected hollow silica spheres was next elaborated by thermo-oxidative decomposition of the organic phase. 

Han, Y.-H. Travas-Sejdic, J. Wright, B. Yim, J.-H., Simultaneous Vapor-Phase Polymerization of PEDOT and a Siloxane into Organic/Inorganic Hybrid Thin films. Macromol. Chem. Phys. 2011,212,521-530. 

Yu et al. (2003) synthesized hybrid thin films containing nanosized inorganic domains from poly(acrylic) and monodispersed colloidal silica with bound 3-(trimethoxysilyl)propyl methacrylate (MSMA) for potential applications as passive films in optical devices. The latter was polymerized with acrylic monomer to form a precursor solution, which was spin-coated and cured to form hybrid films. The silica content in the hybrid thin films was varied from 0 to 50 wt% (Figure 1.302). The coverage area of silica particles by the MSMA decreased with increasing silica content and resulted in the aggregation of silica particles in the hybrid films, and the silica domains were 20-35 nm in size. 

Matsuno R, Otsuka H, Takahara A (2006) Polystyrene-grafted titanium oxide nanoparticles prepared through surface-initiated nitroxide-mediated radical polymerization and their application to polymer hybrid thin films. Soft Matter 2(5) 415... 

Moleculady mixed composites of montmorillonite clay and polyimide which have a higher resistance to gas permeation and a lower coefficient of thermal expansion than ordinary polyimides have been produced (60). These polyimide hybrids were synthesized using montmorillonite intercalated with the ammonium salt of dodecylamine. When polymerized in the presence of dimethyl acetamide and polyamic acid, the resulting dispersion was cast onto glass plates and cured. The cured films were as transparent as polyimide. 

The results demonstrated that both compression and shear can induce the formation of C-C bonds between sp-hybridized carbons atoms, which leads to polymerization within the SAM. Interestingly, it was found that the location of these reactive sites within the film could influence the calculated friction. For instance, if the diacetylene components in the chains were close to the tip/film interface, reactions between the film and tip could occur, which led to wear and high friction. On the other hand, if the diacetylene moieties were far from the tip, the reactions did not lead to wear and had little effect on the average calculated friction. These observations demonstrate that a proper treatment of the chemical reactivity of the system may be necessary in some cases to calculate friction accurately. 

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