abstract
The copper-catalyzed alkyne azide cycloaddition (CuAAC) reaction was combined with sol-gel reactions for the production of bridged silsesquioxanes (BSs) in which hexyl and icosanyl chains are pendant and anchored on a single position to a triazole ring. The influence of the alkyl chain length on the structure of the BSs, represented by the notation Cn/siloxane (where n = 6 and 20), was examined. The C20/siloxane hybrid is a hydrophobic material that exhibits a hierarchically structured lamellar bilayer organization, a texture composed of microplates of nanometer thickness, and a reversible time-independent order/disorder phase transition (onset at 60 degrees C). The driving forces for self-assembly are van der Waals interactions between the icosanyl chains and - interactions between the triazole rings. In the essentially amorphous C6/siloxane hybrid, the latter contribution promotes the genesis of a pre-lamellar phase similar to that found in C20/siloxane.
keywords
H STRETCHING MODES; SOLID-STATE NMR; HYBRIDS; CONFORMATION; MONOLAYERS; SILSESQUIOXANES; SPECTROSCOPY; HYDROLYSIS; SILICATES; MOBILITY
subject category
Chemistry
authors
Nunes, SC; Burglova, K; Hodacova, J; Ferreira, RAS; Carlos, LD; Almeida, P; Cattoen, X; Man, MWC; Bermudez, VD
our authors
Luís Carlos
Full professor
Maria Rute de Amorim e Sá Ferreira André
Full professoracknowledgements
This work was supported by the Fundacao para a Ciencia e a Tecnologia (FCT) (SFRH/BPD/63152/2009, grant to S. N.) and the Fundo Europeu de Desenvolvimento Regional (FEDER) (contracts PTDC/QUI-QUI/100896/2008, PTDC/CTM-BPC/112774/2009, Pest-C-CTM/LA0011/2013, Pest-OE/QUI/UI0616/2014 and Pest-OE/SAU/UI0709/2014), COST Action (MP1202880, Rational design of hybrid organic-inorganic interfaces), the Czech Science Foundation (P108/12/1356), the Czech/French BARRANDE Hubert Curien Programme (7AMB12FR004) and the French Embassy in Prague (grant to K. B.). The authors thank Dr. Sonia Sousa and Prof. Ana Ramos (University of Beira Interior) for the angle contact measurements and Dr. P. Ferreira (CICECO, University of Aveiro) for the nitrogen adsorption measurements.