Microstructures by Solvent Drop Evaporation on Polymer Surfaces: Dependence on Molar Mass
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- 作者：Guangfen Li ; Hans-Jü ; rgen Butt ; Karlheinz Graf
- 刊名：Langmuir
- 出版年：2006
- 出版时间：December 19, 2006
- 年：2006
- 卷：22
- 期：26
- 页码：11395 - 11399
- 全文大小：223K
- 年卷期：v.22,no.26(December 19, 2006)
- ISSN：1520-5827
文摘
When a solvent drop evaporates from a polymer surface, it leaves behind a characteristic structure, typically a crater.We deposited toluene drops with a microsyringe onto planar polystyrene (PS) surfaces and analyzed the surfacetopography after drying. For low molar mass PS (Mw = 20.9-24.3 kDa) dotlike protrusions with a ridge at theperiphery formed on the polymer surface. With increasing molar mass the central region decreased in height. At Mw= 29.6-643 kDa a craterlike structure with a depression in the center and a ridge was observed. At even higher molarmass, irregular structures without rotational symmetry occurred. We explain the observed dependence on the molarmass with a different degree of entanglement, leading to different dissolution rates and different diffusion constants.