Kinetics of Polymerization of a Liquid with Nanosize Structural Heterogeneities
| العنوان: | Kinetics of Polymerization of a Liquid with Nanosize Structural Heterogeneities |
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| المؤلفون: | Joseph Khouri, G. P. Johari |
| المصدر: | The Journal of Physical Chemistry B. 115:13489-13501 |
| بيانات النشر: | American Chemical Society (ACS), 2011. |
| سنة النشر: | 2011 |
| مصطلحات موضوعية: | Materials science, Enthalpy, Kinetics, technology, industry, and agriculture, macromolecular substances, Silsesquioxane, Surfaces, Coatings and Films, chemistry.chemical_compound, Chemical engineering, Polymerization, chemistry, Polymer chemistry, Materials Chemistry, Molecule, Physical and Theoretical Chemistry, Endotherm, Post polymerization, Stoichiometry |
| الوصف: | We report the effects of chemically reacting, nanometer-size structural heterogeneity on a polymerization process. Heterogeneity is introduced by adding 2 nm size molecules of polyhedral oligomeric silsesquioxane with multiepoxide groups (POSS) while maintaining stoichiometry of a polymerizing triamine-diepoxide mixture. Calorimetric studies show that POSS addition first increases the polymerization rate and then decreases it progressively more. In the presence of nanometer-scale structural heterogeneity, diffusion-controlled kinetics begins sooner in time. The enthalpy of polymerization decreases with the amount of POSS heterogeneity according to the mixture rule; the glass-liquid transition endotherm of the partially polymerized state becomes broader, and the enthalpy of post polymerization decreases. The POSS-alone mixture polymerizes relatively slower, and the glass-liquid transition exotherm of the polymerized state is indistinguishably broad. Both are attributed to the distribution of diffusion rates or dispersive kinetics, and the development of dynamic heterogeneity more rapidly for the POSS-only mixture than for others. Increase in the polymerization rate on initial addition of nanometer-size POSS and then decrease on further addition is explained in terms of decoupling of diffusion from viscous flow, that is, when the diffusion rate decreases less rapidly with the polymerization time than the viscosity increases. |
| تدمد: | 1520-5207 1520-6106 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a9ee3512b3a776200adc7306e19ff3de https://doi.org/10.1021/jp2071343 |
| رقم الأكسشن: | edsair.doi.dedup.....a9ee3512b3a776200adc7306e19ff3de |
| قاعدة البيانات: | OpenAIRE |
Find this issue from the American Chemical Society | تدمد: | 15205207 15206106 |
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