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Nanomaterials are applied with great success in biomedical applications as templates for the development of new generation devices, which can be used to solve current health problems. These new nanoscale systems are designed with multifunctions to perform specific and selective tasks. One of the most important applications of this new nanotechnology; focuses on developing new systems for the controlled release of drugs, mainly due to their capability to improve the temporal and spatial presentation of drugs in the body and their ability to protect them from physiological degradation or elimination. Hydrogels, porous silicon (PSi), and PSi-composites have been widely adopted in this field due to their biological, morphological, and physicochemical properties; which can be tuned to obtain sensitive responses to physiological stimuli. Despite the fact that some recent academic papers have shown the benefits of these nanomaterials in a wide range of biological applications, more in vivo studies are needed to take these hybrid systems towards clinical trials. In this mini-review some of the hydrogels, PSi, and PSi-composites latest applications and prospects in this field of science are presented.

Poly(dimethylsiloxane-co-methyl-hydridosiloxane) (PDMSMHS) with a OSi(CH 3 ) 2 /OSi(HCH 3 ) molar ratio of 21:1 was functionalized with dimethylallylamine (DMAA) via catalytic hydrosilylation using Karstedt's catalyst and then quaternized with 1-iodooctane. The functionalized and quaternized co-polysiloxanes (PDMSMHS-1 and PDMSMHS-QAS) were characterized using 1 H, 13 C and 29 Si NMR. The physicochemical properties of the polymeric systems (the differential refractive index increment (dn/dc), the square root of the mean square radius of gyration (< RMS 2 radius > 1/2 ), the average molecular weight (M), and the second virial coefficient (A 2 )) were measured in ethanol using gel permeation chromatography/light scattering (GPC/LS). The low percentage (3-4 %) of amino side groups has an unexpected effect on the co-polymers physicochemical properties because the A 2 experimental value for PDMSMHS-1 and PDMSMHS-QAS (8.87 × 10 −3 and 1.51 × 10 −2 molmLg −2 , respectively) indicates that ethanol is a good solvent.

The glycol alkoxysilanes, tetrakis(2‐hydroxyethyl)silane (THEOS), and tris(2‐hydroxyethyl)methyl silane (MeTHEOS) are water soluble derivatives of tetraethoxysilane (TEOS) and methyltriethoxysilane (MeTEOS) and precursors of the system silane–chitosan reviewed in this work. The glycol modified alkoxysilanes are obtained by transesterification reaction of TEOS or MeTEOS with ethylene glycol. The reaction evolution is monitored by 29Si NMR. It is possible to observe the formation of the various species of glycol alkoxysilanes in equilibrium as the reaction proceeds showing that the oligomers formation is favored at longer reaction times with the final product tendency to gel keeping the complete water solubility. The glycol alkoxysilanes are synthesized at moderated reaction conditions, by using the Piers–Rubinsztajn (PR) reaction. Additionally, it is already known that THEOS is compatible with different natural polysaccharides as chitosan and the same behavior has been demonstrated in this work for MeTHEOS. Several reports refer studies regarding the system THEOS–polysaccharides to synthesize hybrid materials. The system THEOS–chitosan is known but the characterization as well as the way silane–chitosan interact has not been studied in detail. In the present report, chemical evidence of the covalent interactions THEOS– and MeTHEOS–chitosan based on NMR studies (13C and 29Si) are presented as intended.

The swelling behavior of poly(acrylic acid‐co‐itaconic acid)/NaOH hydrogel as well as its ability for iron and copper rust removal was studied and established for the first time. Through an experimental design, the influence of the synthesis parameters on hydrogel response was determined. It was found that pH‐responsiveness dependence of hydrogel determines its application. In alkaline media, the hydrogel acted as superabsorbent, while in acidic, the most outstanding property was its pickling capability that allowed to clean carbon steel and copper metallic surfaces. Infrared, thermogravimetry, and scanning electron microscopy were performed to determine copolymer formation, thermal properties, and morphology. Metallic crystallographic phases formed during the corrosion processes were determined by X‐ray diffractometer. Hydrogel adhesiveness followed by diffusion and dissolution of metal oxides species was identified as the main steps in the rust removal mechanism. This method offers a new, environmentally friendly perspective to eliminate corrosion from metallic surfaces compared with traditional strategies. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48403.