Dielectric elastomers were prepared on the basis of high molecular weight polydimethylsiloxane-α,ω-diol filled with barium titanate particles having well-defined size and morphology.

A poly(urethane-urea-siloxane) was prepared in a two-step procedure involving the synthesis of a bis-isocyanate prepolymer on the basis of 4,4′-diphenylmethane diisocyanate, a polyether glycol and dimethylol propionic acid, and its extension by reacting with 1,3-bis(3-aminopropyl)tetramethyldisiloxane. The resulted polymer was used in different percentages to prepare three series of interpenetrating networks (IPNs) with polydimethylsiloxane-α,ω-diols with molecular masses, M_n, of 70 000, 230 000 and 370 000 g mol⁻¹. A polydimethylsiloxane–polyethyleneoxide graft copolymer was added as a compatibilizing agent. The IPN precursors were mixed in solution and processed as films. During solvent evaporation, the chemical crosslinking of the polydimethylsiloxane-α,ω-diols occurs with tetraethyl orthosilicate in the presence of dibutyltin dilaurate, while in the case of poly(urethane-urea-siloxane) only physical crosslinking by hydrogen bonds is expected to occur. The morphology and thermal transitions of the resulted networks were examined by scanning electron microscopy, differential scanning calorimetry with dynamic mechanical analysis. The mechanical and dielectric characteristics (dielectric permittivity, loss, strength) of the aged films were studied. Their responsiveness to an external stimulus in the form of an increasing electric field was assessed by electromechanical measurements and expressed as lateral strain. The results were critically analyzed with respect to each other as a correlation with their composition and compared with those obtained for three common commercially available dielectric elastomers.

A new class of elastomers that simultaneously shows sensing, actuation and energy conversion functionalities is synthesized to meet the current requirements for electroactive materials. These new materials consist of a silicone network (polydimethylsiloxane-α,ω-diol crosslinked through chain ends) semi-interpenetrated with different percentages (2, 5, and 10 wt%) of polyimide derivatives stepwise modified by different strategies to improve the compatibility with the silicone core network. By addressing the right chemical pathway, the resulting semi-interpenetrated structures (S-IPNs) show noticeable dielectric permittivity, eps′ (up to 11), and breakdown strength, Ebd (up to 88 μm V⁻¹), improvements as compared with the starting polymers (silicone with eps′ = 2.9 and Ebd = 38 μm V⁻¹ and our best polyimide with eps′ = 6.2 and Ebd = 23 μm V⁻¹). The S-IPNs with 10 wt% polyimide are able to gain energy up to 132 mJ cm⁻³ at 100% strain and up to 164 mJ cm⁻³ at maximum strain to develop large actuation strain (up to 8.7%) and show very good piezo-response (up to 44 pm V⁻¹), making them highly suitable for cutting-edge electromechanical applications. For a better evaluation, S-IPNs are compared with one of the commercially available dielectric elastomers, most often used for this purpose.

Mesoporous silica nanoparticles (MSNs) bearing methyl, thiol or glucose groups were synthesized, and their encapsulation and release behaviors for the anticancer drug Doxorubicin (Dox) were investigated in comparison with nonporous homologous materials. The chemical modification of thiol-functional silica with a double bond glucoside was completed for the first time, by green thiol-ene photoaddition. The MSNs were characterized in terms of structure (FT-IR, Raman), morphology (TEM), porosity (nitrogen sorption–desorption) and Zeta potential measurements. The physical interactions responsible for the Dox encapsulation were investigated by analytic methods and MD simulations, and were correlated with the high loading efficiency of MSNs with thiol and glucose groups. High release at pH 5 was observed in most cases, with thiol-MSN exhibiting 98.25% cumulative release in sustained profile. At pH 7.4, the glucose-MSN showed 75.4% cumulative release, while the methyl-MSN exhibited a sustained release trend. The in vitro cytotoxicity was evaluated on NDHF, MeWo and HeLa cell lines by CellTiter-Glo assay, revealing strong cytotoxic effects in all of the loaded silica at low equivalent Dox concentration and selectivity for cancer cells. Atypical applications of each MSN as intravaginal, topical or oral Dox administration route could be proposed.