Chain dimensions and intermolecular interactions of polysilanes bearing alkyl side groups over the UV thermochromic temperature. (26th June 2015)

• Record Type: Journal Article
• Authors: Jiang, XinYue; Terao, Ken; Chung, Woojung; Naito, Masanobu
• Is Part Of: Polymer. Volume 68(2015)
• Page Start: 221
• Page End: 226
• Publication Date: 2015-06-26
• Subjects: Polysilane -- SAXS -- Intermolecular interaction; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2015.05.018
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: To elucidate temperature change of intermolecular interactions and chain dimensions for poly(dialkylsilane)s with or without thermochromism, synchrotron-radiation small-angle X-ray scattering and UV-absorption measurements were carried out for relatively low-molar mass poly( n -hexylmethyl)silane (PSi-1 ), poly( n -decylmethyl)silane (PSi-2 ), and poly( n -hexylpropyl)silane (PSi-3 ) samples in isooctane over a wide temperature range down to −94 °C. While the dimensional properties for the three polysilanes were almost irrespective of temperature, the second virial coefficient for PSi-2 and PSi-3 significantly decreased and became negative below the thermochromic temperature at −60 °C and −50 °C, respectively. Analyses in terms of the quasi-two-parameter theory for the wormlike chain showed that conformational change detected by UV-absorption behavior does not cause appreciably the unperturbed chain dimensions of the polysilane samples. Furthermore, aggregates were detected by ultra-small-angle X-ray scattering measurements for high molar mass PSi-3 samples at low temperatures. These results indicate that intermolecular interactions between poly(dialkylsilane) molecules become attractive around the thermochromic temperature. Graphical abstract: Highlights: Solution properties of polysilanes were determined over a wide temperature range. Intermolecular interactions become attractive below the UV thermochromic temperature. Polymer dimensions of all three polysilanes are mostly irrespective of temperature. Aggregates were found for high molar mass polysilane samples at low temperatures.