Biodegradable graft copolymers were prepared by gamma radiation-induced graft polymerization of two vinyl monomers, vinyl acetate and vinyl alcohol, onto poly[(R)-3-hydroxybutyric acid]. Success of the grafting reaction was verified by Fourier-transform infrared and nuclear magnetic resonance spectroscopy. Thermal remolding was used to create membranes from the copolymers. We determined tribological and mechanical properties of the membranes obtained. The lowest elongation at break in tensile testing is seen for P(3HB) and the highest for P(3HB-g-VA). Up to 5 N or so, the highest scratch resistance is exhibited by P(3HB-g-VA). Piezoelectric behavior is seen for P(3HB-g-VA) while P(3HB-g-VAc) and plain P(3HB) showed no electric response. Explanation of the piezoelectric behavior in terms of molecular structures is provided.

Vinyl alcohol

Vinyl acetate

10.1080/1023666x.2015.1036225

Cite

Citations (5)

Hybrid ceramic-polymer material for wood coating with high wearing resistance

Materials Research Innovations (2003)

R. Rodrı́guez Miriam Estévez S. Vargas M.A. Mondragón

The synthesis and characterization of a hybrid ceramic-polymer coating with high wearing resistance and designed to cover wood surfaces, are reported in this work. This hybrid material provides a high wearing resistance (400% higher than a conventional commercial product typically used to protect these surfaces); additionally it has a high UV resistance and high transparency and gloss. The wood surfaces were previously treated either with a primer coating or with a special coupling agent, before the hybrid coating was applied; in both cases, good adhesion with the substrate was obtained.

Gloss (optics)

Primer (cosmetics)

Impact resistance

10.1080/14328917.2003.11784766

Cite

Citations (3)

Electrical response of optimized DSSC’s by different dye-mordant-assistant combinations: A multi-time-hierarchical theoretical approach

Results in Physics (2021)

R. Rodrı́guez S. Vargas V. M. Castaño I. Santamarı́a-Holek

The electrical response of dye-based photovoltaic cells upon a sudden illumination is explained in terms of a theoretical approach based on a time-hierarchical emergence of several physical processes. Our approach ensures the coupling the four main processes that take place, namely, the photochemical activation of the cell, the electrical current associated with electron transport, the relaxation of the polarization due to the motion of ions and, finally, the elastic–osmotic effect that produces rapid oscillations in the output photocurrent of the cell when is suddenly illuminated. The model shows that mordants control/modify three relaxation times: the characteristic time of the photochemical activation due to a partial light-blocking, the characteristic time for the electrical current associated with the electron transport due to mordant adsorption into the mesoporous surface, and the polarization relaxation due to a change in the ions transported to the electrodes. The model fits with high-precision the experimental data of the photo-induced current showing highly non-linear time-dependent oscillations.

Photocurrent

Mordant

10.1016/j.rinp.2021.104064

Cite

Citations (2)

Comparative study of the performance of solar cells based on cochineal and Black Dye N749 with several mordant and brighteners

Results in Chemistry (2024)

R. Rodrı́guez S. Vargas

Mordant

10.1016/j.rechem.2024.101913

Cite

Citations (0)

Characterization of novel dental obturation materials

Materials Research Innovations (2006)

Miriam Estévez S. Vargas Haley E. Hagg Lobland Agustín de la Isla Witold Brostow

Abrasion behavior of new nanohybrid polymer + ceramic dental materials designed for filling dental cavities is reported. The polymer matrix is a polyurethane while the dispersed phases include particles of silica and alumina with the diameters below 100 nm. Several commercial obturation materials are investigated by the same technique. The authors' new nanohybrids show clearly superior resistance to abrasion wear – in one case some 20 times better than a commercial sample. Moreover, the new materials exhibit low toxicity, short curing times (<10 min), good dimensional stability (low contraction), high chemical resistance and good pigmentation capacity and they are easy to prepare and show good adhesion to the substrate (dentine or enamel).

Abrasion (mechanical)

Chemical resistance

10.1179/143307507x199399

Cite

Citations (6)