Structural Evolution of Self‐Assembling Nanohybrid Thin Films from Functionalized Urea Precursors

Abstract

Hybrid organic‐inorganic thin films exhibiting patterned structuring on the nanometer scale have been prepared through the controlled hydrolysis‐condensation of enantiomerically pure chiral urea‐based silyl compounds. The thin films are obtained by spin‐coating of sols obtained via acid‐ or base‐catalyzed hydrolytic condensation of these molecular precursors. A self‐templating process is demonstrated via atomic force and transmission electron microscopy, showing the formation of nanometer size aggregates consisting of interconnected spherulates under acidic condition and of assembled fibers under basic conditions.

Effects of structural variation on the self‐assembly of bis‐urea based bolaamphiphiles

“…The urea group combines a C=O hydrogen bond acceptor with two strong N-H hydrogen bond donors, to give a motif that aggregates in a predictable geometry with high cooperativity. 5 It is not surprising that urea units, especially bis-urea motifs have been extensively used, not just to facilitate the formation of robust nanostructures in organic solvent, 6,7 and in water, [8][9][10] but also to successfully produce supramolecular materials, such as gels, 11,12 membranes, 13,14 and thermoplastic elastomers. 15,16 The self-assembly of bis-urea domains has been studied extensively to gain a full understanding of its assembly mechanism [17][18][19] and to obtain hydrogels with targeted properties.…”

Luminescent coatings from bipyridine-based bridged silsesquioxanes containing Eu3+ and Tb3+ salts

“…1,2,[5][6][7][8][9][10][11][12][13][14][15][16][17] These materials exhibit a high loading of the lanthanide complex (up to 11.2 wt%) 16 covalently bonded to the siloxane network, with excellent homogeneity. However, to date, few studies have been devoted to the processing of BS as thin films, 6,8,[16][17][18][19][20] with most investigations focusing on the synthesis of PMO-derived thin films from low molecular weight organosilane precursors. 18,21 As self-assembling groups such as urea create strong H-bonds between the organic fragments, significantly different nanostructures were obtained depending on the reaction conditions used.…”

The Influence of Arylene and Alkylene Units on the Structuring of Urea‐Based Bridged Silsesquioxanes

“…[3] They can be obtained as powders, monoliths [4] or processed as films. [5] Thus, the organic functionalities can easily provide discrete properties to the resulting material according to the desired applications. [6] Subsequently, much effort is being devoted to the structuring of these hybrid materials since additional interesting properties might also be tuned by the organisation of the organic fragments in the hybrid silica framework.…”