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Unformatted text preview: Probing of Cosolvents in Polymer Latex Materials by Using Solvatochromic Fluorescence A LBERT M. B ROUWER , a T ANZEELA N. R AJA , a K OEN B IEMANS , b T IJS N ABUURS , b AND R ONALD T ENNEBROEK b a Universiteit van Amsterdam, Van t Hoff Institute for Molecular Sciences, Amsterdam, the Netherlands b DSM Neoresins, Waalwijk, the Netherlands The process of film formation is of great importance for the application of organic coatings. In waterborne coatings, organic cosolvents are still indispensable, but regulations force the industry to reduce their amounts. Here we describe a method that uses the solvatochromic fluorescence of a probe molecule copolymerized in an emulsion polymerization process with different monomers to shed light on the partitioning of cosolvents in polymer latex materials. The formulation of the latex with organic cosolvents that are not very water soluble leads to a quantifiable redshift of the emission of the probe. The transfer of the cosolvent upon mixing of cosolvent-containing and cosolvent-free compartments can also be monitored. Key words: fluorescence; solvatochromism; emulsion polymers; waterborne coatings; volatile or- ganic components; film formation Waterborne Organic Coatings: From Emulsions to Films Coatings made from organic polymers play a key role in modern technology. Because of the chemical compatibility of organic polymers with organic sol- vents, it is most convenient to use those solvents as the medium from which the coatings are applied to their substrates. Unfortunately, volatile organic solvents can cause health problems for people exposed to them, and the solvents pose a potential threat to the environment. It is therefore attractive to work with waterborne coat- ings, but then, of course, the polymer is not directly soluble. Instead, the polymer is obtained, for example, by emulsion polymerization 1 as surfactant-stabilized particles in water, commonly known as a latex. The process of formation of a coherent film from a latex is different from that of a solventborne polymer. The goal of our research is to shed more light on the de- tails of this film formation process, using fluorescence spectroscopy as a minimally invasive technique. Address for correspondence: Prof. dr. A.M. Brouwer,, Universiteit van Amsterdam, Van t Hoff Institute for Molecular Sciences, Nieuwe Achter- gracht 129, 1018 WS Amsterdam, the Netherlands. email@example.com The process of film formation from waterborne or- ganic coatings has been extensively investigated, but the knowledge gathered is still insufficient to allow a priori prediction of film properties from the latex com- position. In the industry, optimization of film forming materials rests largely on empirical observations, such as the minimum film formation temperature, as well as calorimetric measurements, such as differential scan- ning calorimetry, which give direct information about phase transitions, either in the wet state or after casting and drying a film.and drying a film....
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This note was uploaded on 07/11/2010 for the course SPECTOGRAP 545 taught by Professor Gdf during the Spring '10 term at AIB College of Business.
- Spring '10