Dimensional Characterizations from Rod Stars to Brushes of Polymers with a Low Degree of Polymerization

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• 作者：Moriya Kikuchi ; Atsushi Takahara ; Seigou Kawaguchi
• 刊名：Macromolecules
• 出版年：2017
• 出版时间：January 10, 2017
• 年：2017
• 卷：50
• 期：1
• 页码：324-331
• 全文大小：438K
• ISSN：1520-5835

文摘

Dimensional characterizations from rod stars to brushes (PSt-g-HIC-32) with a relatively low degree of polymerization of the main chain have been studied in tetrahydrofuran (THF) at 25 °C by employing synchrotron radiation small-angle X-ray scattering, static and dynamic light scatterings, and viscosity measurements. The rod stars and brushes consist of a flexible linear polystyrene (PSt) main chain and 32 n-hexyl isocyanate (HIC) units in each side chain. Eight PSt-g-HIC-32 samples with a weight-average degree of polymerization (N_M) of 11–495 of the main chain and a narrow molecular weight distribution (M_w/M_n) of 1.08–1.17 were prepared using a recycling preparative size-exclusion chromatography (SEC) system. The mean-square radius of gyration (⟨S²⟩), hydrodynamic radius (R_H), and intrinsic viscosity ([η]) of the stars and brushes were tabulated. The absolute calibration curve obtained in SEC analysis, scattering form factor, and ρ (=⟨S²⟩^1/2/R_H) parameter indicated a continuous change in the shape from the rod star to rod brush on increasing the aspect ratio of the main chain to the side chain. The N_M dependences of ⟨S²⟩, R_H, and [η] were consistently and quantitatively described using the current theories based on a wormlike (sphero-) cylinder model by taking into account the effective protruding effects of the side chains near the ends of the main chain.