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It is widely recognized that the surface properties of paper depend on the fibrous matrix and the final surface treatment applied to the paper. Regarding chemical paper surface treatments, an important issue is the evaluation of the penetration of chemical compounds into the fibrous matrix, as the chemicals can potentially cause changes in the intrinsic properties of paper. The work presented here aimed to use Fourier transform infrared (FT-IR) spectroscopy to study paper surface sizing, namely, the penetration of the sizing chemicals into the paper structure. Two different surface sizing formulations were applied to paper produced from Eucalyptus globulus bleached pulp (reference paper): both contain 90% (w/w) cationic starch, but one contains 10% (w/w) poly(styrene-co-maleic anhydride) whereas the other contains 10% (w/w) poly(styrene-co-butyl acrylate). The surface-sized paper sheets were further manually delaminated, so that the top surfaces as well as the internal layers could be analyzed by FT-IR spectroscopy. A non-surface-sized sample was taken as the reference. From the spectroscopic results, it was possible to detect the presence of the copolymers on the paper top surfaces, despite the application of only small amounts of these chemicals in the surface sizing. However, the chemicals were not found in the layers closest to the surface (30-40 µm from the top), leading to the conclusion that the penetration of the sizing formulations into the fibrous matrix was insignificant (at least up to this distance). Infrared spectroscopy data also showed that the calcium carbonate added as a filler was always present at higher concentration in the analyzed inner layers than at the top surface, for the reference paper as well as the sized papers.

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The effect of the addition of two [4-butyltrimethylammonium]-xylan chloride polyelectrolytes (BTMAXs) on bacterial cellulose (BC) was evaluated. The first strategy was to add the polyelectrolytes to the culture medium together with a cell suspension of the bacterium. After one week of cultivation, the films were collected and purified. The second approach consisted of obtaining a purified and homogenized BC, to which the polyelectrolytes were added subsequently. The films were characterized in terms of tear and burst indexes, optical properties, surface free energy, static contact angle, Gurley porosity, SEM, X-ray diffraction and AFM. Although there are small differences in mechanical and optical properties between the nanocomposites and control films, the films obtained by BC synthesis in the presence of BTMAXs were remarkably less opaque, rougher, and had a much lower specular gloss. The surface free energy depends on the BTMAXs addition method. The crystallinity of the composites is lower than that of the control material, with a higher reduction of this parameter in the composites obtained by adding the BTMAXs to the culture medium. In view of these results, it can be concluded that BC–BTMAX composites are a promising new material, for example, for paper restoration.

High-voltage Li metal solid-state batteries are in the spotlight of high energy and power density devices for the next generation of batteries. However, the lack of robust solid-electrolyte interfaces (SEI)...