Mapping Phase Diagrams of Polymer Solutions by a Combination of Microfluidic Solution Droplets and Laser Light-Scattering Detection

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• 作者：Yonggang Shangguan ; Dameng Guo ; Hui Feng ; Yuan Li ; Xiangjun Gong ; Qianjin Chen ; Bo Zheng ; Chi Wu
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：April 8, 2014
• 年：2014
• 卷：47
• 期：7
• 页码：2496-2502
• 全文大小：385K
• 年卷期：v.47,no.7(April 8, 2014)
• ISSN：1520-5835

文摘

Conventional mapping of a phase diagram of a polymer in a solvent requires a substantial amount of polymer (e.g., at least of the order of 100 mg of narrowly distributed samples with different molar masses) and may take months or even years to reach the true two phase equilibrium at each given temperature, especially when the polymer concentration is high. This is why good phase diagrams of polymer solutions are rare in the literature. To solve such a problem, we developed a Teflon microfluidic device to prepare and store a series of droplets (10 nL) at different polymer concentrations inside a glass capillary. The phase transition inside each polymer solution droplet sealed and isolated in immiscible fluorohydrocarbon could be quickly and precisely monitored by a newly developed small angle laser light scattering detector. Using poly(vinyl acetate) (PVAc) in isobutyl alcohol and in benzene as two examples, we demonstrated that a combination of microfluidic device and small angle light scattering enables us to map the phase diagram of a polymer in a given solvent within hours by using only a few mg of the sample because (1) each droplet contains no more than 10 渭g polymer and (2) the phase-transition induced interchain association inside each droplet can be quickly and sensitively detected. We have demonstrated that two sets of a total of eight precisely mapped phase diagrams of four PVAc fractions in the two solvents can be reasonably scaled together to form a master curve.