Raman Open Database: first interconnected Raman-X-ray diffraction open-access resource for material identification.

Detailed crystallographic information provided by X-ray diffraction (XRD) is complementary to molecular information provided by Raman spectroscopy. Accordingly, the combined use of these techniques allows the identification of an unknown compound without ambiguity. However, a full combination of Raman and XRD results requires an appropriate and reliable reference database with complete information. This is already available for XRD. The main objective of this paper is to introduce and describe the recently developed Raman Open Database (ROD, http://solsa.crystallography.net/rod). It comprises a collection of high-quality uncorrected Raman spectra. The novelty of this database is its interconnectedness with other open databases like the Crystallography Open Database (http://www.crystallography.net/cod and Theoretical Crystallography Open Database (http://www.crystallography.net/tcod/). The syntax adopted to format entries in the ROD is based on the worldwide recognized and used CIF format, which offers a simple way for data exchange, writing and description. ROD also uses JCAMP-DX files as an alternative format for submitted spectra. JCAMP-DX files are compatible to varying degrees with most commercial Raman software and can be read and edited using standard text editors.

Unveiling the hybrid interface in polymer nanocomposites enclosing silsesquioxanes with tunable molecular structure: Spectroscopic, thermal and mechanical properties.

Organic-inorganic nanobuilding blocks (NBBs) based on silsesquioxanes (SSQs) have potential applications as nanofillers, thermal stabilizers, and rheological modifiers, which can improve thermomechanical properties of polymer hosts. The possibility to tune both siloxane structure and pendant groups can promote compatibilization and peculiar interactions with a plethora of polymers. However, the control on SSQs molecular architecture and functionalities is usually delicate and requires careful synthetic details. Moreover, investigating the influence of NBBs loading and structure on the hybrid interface and, in turn, on the polymer chains mobility and mechanical properties, may be challenging, especially for low-loaded materials. Herein, we describe the preparation and characterization of polybutadiene (PB) nanocomposites using as innovative fillers thiol-functionalized SSQs nanobuilding blocks (SH-NBBs), with both tailorable functionality and structure. Swelling experiments and, more clearly, solid-state NMR, enlightened a remarkable effect of SH-NBBs on the molecular structure and mobility of the polymeric chains, envisaging the occurrence of chemical interactions at the hybrid interface. Finally, thermal and DMTA analyses revealed that nanocomposites, even containing very low filler loadings (i.e. 1, 3 wt%), exhibited enhanced thermomechanical properties, which seem to be connected not only to the loading, but also to the peculiar cage or ladder-like architecture of SH-NBBs.

Influence of Sol-Gel Conditions on the Growth of Thiol-Functionalized Silsesquioxanes Prepared by In Situ Water Production.

Thiol-functionalized oligosilsesquioxanes have been synthesized by sol-gel chemistry via the in-situ water production (ISWP) approach, exploiting the esterification reaction of chloro-acetic acid and 1-propanol. The extent of hydrolysis-condensation of 3-Mercaptopropyltrimethoxysilane (McPTMS) has been studied by FT-IR and NMR spectroscopy, gel permeation chromatography (GPC) and MALDI-TOF techniques. The esterification reaction plays a key role in ruling out the oligomer structural development. In this work, we have investigated the influence of the theoretical amount of water available for the organosilane hydrolysis, defined by the ratio of chloro-acetic acid to McPTMS in the reaction mixture, and the role of different catalysts like trifluoroacetic acid (TFA) and dibutyldilauryltin (DBTL). The behavior of the catalyst is complex since, according to its nature, it may improve the kinetics of the sol-gel reactions and the esterification reaction as well. Comparing the reactions carried out with under-stoichiometric water content, the degree of condensation of the silsesquioxanes is higher if the reaction is catalyzed by TFA than by DBTL, because TFA may improve the kinetics of both hydrolysis-condensation and esterification reactions. The use of DBTL in under-stoichiometric and stoichiometric hydrolytic conditions raises the yield in ladder-like structures. The degree of condensation generally increases increasing the hydrolysis ratio as well as the yield in cage-like structures. However, when an over-stoichiometric amount of water is provided for the sol-gel reaction, condensation degree and ratio among cages and ladder-like structures appear unaffected by the employed catalyst.