Micrografía SEM a 1.467X de magnitud, con un HV de 10.00kV (WD: 10.6 mm). Fractura de una película polimérica compuesta de metacrilatos (MMA/BA/HEMA) en precencia de nanotubos de carbono multipared (0.5%) mediante polimerización en miniemulsión. Los nanotubos previos a la polimerización fueros sometidos a un tratamiento de ultrasonido en agua y en presencia de polyvinilpirrolidona. Después de la polimerización a 70ºC, el látex obtenido fue de color negro y homógeno sin cuágulos y estable
TEM micrograph of a cross-section of an acrylic polymer film for coatings applications. In the image, the darkest component forms a honeycomb microstructure around the lightest phase. The dark phase was composed of tannic acid, a naturally occurring polyphenol, and the light phase was consisting of poly(N-vinyl pyrrolidone-co-butyl acrylate-co-methyl methacrylate) (P(NVP/BA/MMA) polymer particles produced by seeded semibatch emulsion polymerization. For the preparation of the sample, 5% based on polymer of tannic acid was added as an aqueous solution to the P(NVP/BA/MMA) polymer dispersion. The blend was stirred for 30 minutes, cast into a silicone mould and dried for 7 days at 55 % relative humidity and 25 ºC. The resulting polymer film was cut employing a microtome and stained with ruthenium tetraoxide (RuO4) in order to increase the contrast of the aromatic rings of tannic acid. The staining process allowed the observation of the honeycomb microstructure formed by tannic acid around the polymer particles. The honeycomb microstructure was formed as a result of the strong hydrogen bonds between the aromatic hydroxyl groups of tannic acid and the amide groups of the pyrrolidones present in the polymer, which promoted the homogeneous distribution of tannic acid around the polymer particles. This conclusion was made by comparing the microstructure of the materials prepared without the pyrrolidone: The tannic acid formed aggregates instead of the continuous honeycomb microstructure. The P(NVP/BA/MMA)/tannic acid hydrogen bonded materials presented greater Young’s modulus and yield stress as a result of the hard honeycomb structure. The high stiffness presented by these materials make them excellent candidates for applications that require hard polymer films and opens the way for the complete replacement of solventborne coatings.
2019 Photography contest winner
Description: AFM phase image of a double crystalline PE494.9-b-PEO515.2 diblock copolymer. The long edge on lamellae in the center of the image correspond to the polyethylene block crystals. To the top and the bottom of the image, flat on lamellae can be observed, which can correspond to both PE and PEO block crystals. The thin vertical short lamellae on the middle of the image (looking like fish bones) are most probably poly(ethylene oxide) lamellae. Author: Ms. Eider Matxinandiarena
2018 Photography contest winner
2018 Awarded picture: "Centipede" by Mr. Jesus Alvaro Iregui. Description: AFM phase image of an electrospun PCL-DGEBA nanofiber. Due to the spinning process, it is observed a high degree of crystalline orientation
4th Scientific Photography Award
Awarded picture: AFM phase image of the top surface of a dried film of latex with particles polymerized in presence of cellulose nanocrystals. Elodie Limousin
3rd Scientific Photography Award
"The eyes": Double crystalline nascent spherulite. AFM micrographs of a PEO-b-PCL diblock copolymer taken at a room temperature by Ms. Jordana Palacios.
II Scientific Photograph Award
Awarded picture: "SEM micrograph showing multiscale roughness" by Ms. Ana Belén López
