Chain expansion process from knotted globule. (12th September 2019)

• Record Type: Journal Article
• Authors: Nakata, Mitsuo; Nakamura, Yoshiki; Maki, Yasuyuki; Dobashi, Toshiaki
• Is Part Of: Polymer. Volume 178(2019)
• Publication Date: 2019-09-12
• Subjects: Knotted globule -- Unknotting -- Chain collapse -- Chain expansion; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2019.06.007
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Knotting in a polymer chain was investigated by observing the chain expansion process from a collapsed chain for the solution of poly(methyl methacrylate)(PMMA) with Mw = 1.22 × 10 7 in the mixed solvent tert-butyl alcohol + water(2.5 vol%). Because of very slow phase separation in the solution the chain collapse after a temperature drop and chain expansion after a jump were determined by static light scattering. PMMA chain was shown to collapse rapidly to an unknotted globule, which subsequently contracted slowly to a knotted globule. The chain expansion process from the knotted globule was dominated by the chain compactness and the degree of knotting of the initial globule. A complete chain expansion from a heavily knotted globule often required a very long time indicating an existence of long-lived knots. The chain expansion from the unknotted globule occurred too fast to be followed by scattering experiment. Graphical abstract: Image 1 Highlights: Collapse and expansion of PMMA chain can be observed far below the θ-point. Chain collapse occurs rapidly by crumpling first and slowly by knotting. Degree of Knotting in a globule changes with the quench depth and aging time. Observed chain expansion process reflects unknotting process in a globule.