کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5370447 1388494 2006 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Monolayer characteristics of stereoregular PMMA at the air/water interface
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
Monolayer characteristics of stereoregular PMMA at the air/water interface
چکیده انگلیسی

Behaviors of isotactic, atactic and syndiotactic poly(methyl methacrylate) (PMMA) monolayers at the air/water interface were investigated. The monolayer characteristics of the three stereoisomers were studied and compared in terms of surface pressure-area per molecule (π-A) isotherm, hysteresis and relaxation phenomena, and the phase images observed from Brewster angle microscopy (BAM). The results show that iPMMA monolayer has a more extended and compressible property, and exhibits pronounced hysteresis and relaxation phenomena among the three tactic PMMAs. Such characteristics can reasonably be attributed to the higher flexibility of chains segments of iPMMA as estimated from its lower Tg. On the other hand, sPMMA, the one with the highest Tg, forms a more condensed monolayer due to the high cohesive interaction among polymer chains. The BAM images show that PMMA molecules are not well extended on the subphase and thus, aggregative phases were observed even in a state corresponding to the gas phase. The aggregative structures are especially significant on sPMMA monolayer, which is consistent with the results estimated from the π-A isotherms. When the temperature is elevated from 25 to 40 °C, all the monolayers of the three stereoisomers become more expanded and compressible due to the increase in chain flexibility.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Surface Science - Volume 252, Issue 12, 15 April 2006, Pages 4312-4320
نویسندگان
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