Accepted Article Photoinduced nanostructured organosilica hybrids Céline Croutxé-Barghorn 1* , Abraham Chemtob 1 , Lingli Ni 2 , Irena Deroche 3 1 Laboratory of Macromolecular Photochemistry and Engineering, University of Haute-Alsace, 3b rue Alfred Werner, 68093 Mulhouse Cedex, France. 2 Key Laboratory for Palygorskite Science and Applied Technology of Jiangsu Province, College of Chemical Engineering, Huaiyin Institute of Technology, 223003 Huaian, People’s Republic of China 3 Institut de Science des Matériaux de Mulhouse, UMR-CNRS 7361, University of Haute-Alsace, 3b rue Alfred Werner 68093, Mulhouse Cedex, France. *Corresponding author: celine.croutxe-barghorn@uha.fr Abstract Organosilane self-assembly is an efficient way to synthesize nanostructured hybrid materials. The key parameters of the process are based on selecting appropriate precursor architecture (mono-, bis- or multi-sylilated organosilane) under adapted sol-gel reaction and processing conditions. The general mechanism of this template-free process relies on the generation of amphiphilic species that can self-assemble and cross-link subsequently by siloxane Si-O-Si condensation. Self-organization results thus from an interplay between enthalpic and entropic contribution. Recently, we demonstrated the potential of the photoinduced synthesis and ordering of nanostructured hybrids as an original and attractive route to afford well-condensed organosilicate films. This work will review the driving forces of this approach encompassing the structure of the organosilane precursor, thermodynamic and kinetic parameters. Introduction Siloxane-based hybrid materials, referred to as polysilsesquioxanes (polySQ), have shown their potential over the last two decades, and opened new application opportunities in the field of nanocomposites 1 . They are typically synthesized via a sol-gel process, affording a variety of chemical structures, physicochemical and textural properties 2 . Most hybrid sol-gel materials reported in the literature are amorphous. Turning to crystal-like structures exhibiting a regular arrangement of the organic chains still remains not trivial although there is a growing attractiveness in catalysis, optoelectronics and polymer nanocomposites… The two main synthetic routes to achieve these types of materials are either surfactant templating 3-4 or organosilane supramolecular self-assembly 5 . This last approach based on weak interactions (i.e., Van der Waals, π-π stacking and H-bonding) between specific organic substituents during the precursor's hydrolysis and polycondensation, avoids template extraction after synthesis to exploit the nanostructuration, and yields long-range organized polySQ. The pioneering works in this area have focused on organosilanes with straight-chain hydrophobic group of variable lengths attached to a single 6-8 or double 9-10 terminal hydrolysable SiX 3 group (X = OCH 3 , OCH 2 CH 3 , Cl, etc.). This versatility has paved the way for a better This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/pi.5300 This article is protected by copyright. All rights reserved.