Scanning electric potential microscopy (SEPM) together with noncontact AFM images were obtained from the surfaces of two latex films: the first is a self-arrayed poly(styrene-co-hydroxyethyl methacrylate) macrocrystal, while the other is a thin film formed by coagulation of polystyrene particles at the latex liquid surface, under exposure to chloroform vapor. In both cases, large electric potential differences are detected by the microscope probe between adjacent domains in the films. Domains with positive or negative potentials reach a few hundred nanometers in size. These dielectric films are thus mosaics of electrically charged domains, and their electroneutrality is only observed at the macroscopic level.

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Homopolymer polystyrene films tinted with methylene blue and other hydrophilic cationic dyes are made following a new two-step procedure:  dye adsorption in latex particles, followed by polymer plasticization with a suitable solvent. The dyed polymer is soluble in nonpolar solvents, and the dyes do not phase separate, even in nonsolvents for the pure dye salts. Microanalytical data on the particles and films were acquired using energy-loss spectroscopy imaging (ESI-TEM) and scanning electric potential microscopy (SEPM). The results are interpreted considering that (i) the polystyrene latex particles have a mild ionomer character, due to the charged sulfate groups arising from the polymerization initiator and bound to the chain ends; (ii) there is formation of ion pairs made out of dye cation and chain-end sulfate; (iii) the cationic dye self-associates, as evidenced by a pronounced metachromatic behavior. A nonpolar polymer can thus be made compatible with a basic dye without any special chain modification, just by using this new procedure based on dye sorption followed by diffusion.

There are increasing environmental and economic demands for the production of chemicals of industrial interest from renewable resources. Among the renewable products, short‐chain carboxylic acids (C1‐C6) stand out due to their importance in many sectors of the economy. Within this class, a wide variety of acids are industrially valuable as the precursors of many other chemicals for different applications, technological solutions, and markets. This makes it difficult to identify the most promising from a technical and economic standpoint. In this work, data on scientific papers and patents published between 2008 to 2017, related to the main bio‐based carboxylic acids, are used to identify the acids that are generating growing scientific and industrial interest. The biochemical processes in patents associated with the production of such acids are evaluated using a multicriteria approach that integrates valuation patent criteria. The results of this study show that acids that are of substantial commercial interest, such as acetic, citric, lactic, acrylic, and methacrylic acids, have the highest growth rate both in scientific papers and patents. In terms of biochemical processes, the multicriteria decision analysis showed that the most relevant processes described in patents were associated with ‘drop‐in’ acids such as methacrylic, adipic, maleic, acrylic, and glutaric acids. There is also a clear indication of the emergence of studies on low volume acids such as acetoacetic, acetolactic, muconic, and levulinic acids. In conclusion, the analysis shows that emerging scientific and technological production is conservative, focusing on acids with established markets, especially for the substitution of petrochemicals for immediate demand. © 2020 Society of Industrial Chemistry and John Wiley & Sons Ltd