Random Scission of Polymers: Numerical Simulations, and Experiments on Hyaluronan Hydrolosis

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• 作者：Aernout A. Martens ; Nicolaas A. M. Besseling ; Saskia Rueb ; Ernst J. R. Sudho虉lter ; Herman P. Spaink ; Louis C. P. M. de Smet
• 刊名：Macromolecules
• 出版年：2011
• 出版时间：April 26, 2011
• 年：2011
• 卷：44
• 期：8
• 页码：2559-2567
• 全文大小：955K
• 年卷期：v.44,no.8(April 26, 2011)
• ISSN：1520-5835

文摘

We present a study of the random scission process of polymers, in which numerical simulations are combined with experimental investigations into the acid hydrolysis of the polysaccharide hyaluronan (HA), in particular at pH 1.1 and 50 掳C. As input for the simulations, an initial molecular weight distribution (MD₍₀₎) and the hydrolysis rate constant (k_h) are needed. The first was obtained using agarose gel electrophoresis followed by densitometric analyses, by which we determined the evolution of the full molar-mass distribution during hydrolysis. The rate constant was experimentally obtained by two independent techniques. Kinetic plots were obtained from both the number- and the weight-average molar mass (M_n and M_w, respectively), converted to degrees of polymerization (N_n and N_w, respectively), and from these, k_h values for HA hydrolysis were derived. For confirmation, k_h was also determined from the evolution of the concentration of reducing chain ends. Experimentally determined k_h values were used as input for the model, and the evolution of MD during hydrolysis was simulated for various hypothetical MD₍₀₎ functions as well as for an experimentally determined MD₍₀₎ curve. Agreement between experimental and simulated results demonstrated consistency of the model and indicates that acid hydrolysis of hyaluronan can indeed be considered a random scission process. We show that for cases where the initial molar mass distribution is not of the Kuhn-type鈥攚hich is often the case鈥攖he value for the k_h determined from the evolution of M_n is more accurate than that obtained from M_w.