Kinetics of Polymer Interfacial Reactions: Polymer Brush Formation by Click Reactions of Alkyne End-Functional Polymers with Azide-Functional Substrates

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• 作者：Shuo Zhang ; Thu Vi ; Kai Luo ; Jeffrey T. Koberstein
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：August 9, 2016
• 年：2016
• 卷：49
• 期：15
• 页码：5461-5474
• 全文大小：662K
• 年卷期：0
• ISSN：1520-5835

文摘

Attenuated total reflectance infrared spectroscopy (ATR-IR) is used to directly measure the rates of copper-catalyzed 1,3-dipolar cycloaddition reactions between alkyne-terminated polystyrene and poly(n-butyl acrylate) and azide-functional substrates in the good solvent DMF. Four regimes of behavior are observed: initially, the reaction rate is diffusion-controlled scaling with t^1/2; in the crossover regime at the onset of chain overlap, the rate scales with ln(t); the rate then accelerates briefly; and finally, in the terminal or penetration-limited regime, the logarithm of areal density scales linearly with time. Kinetic behavior in the diffusion-limited, crossover, and penetration-limited regimes corresponds well to the predictions of Ligoure and Leibler. The blob model suggests that the acceleration in rate is due to lateral chain contraction during the mushroom to brush transition. A theory is presented to predict that the areal density at saturation should scale as Σ_saturation ∼ M_w^–1.2 for good solvents, and experimentally we find M_w^{–0.93±0.04} scaling.