Small-angle neutron scattering study on block and gradient copolymer aqueous solutions

• Published in: Polymer (Guilford) Vol. 47; no. 21; pp. 7572 - 7579
• Main Authors: Okabe, Satoshi, Seno, Ken-ichi, Kanaoka, Shokyoku, Aoshima, Sadahito, Shibayama, Mitsuhiro
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 04.10.2006; Elsevier
• Subjects: Applied sciences; Electrical, magnetic and optical properties; Exact sciences and technology; Gradient copolymer; Microphase separation; Organic polymers; Physicochemistry of polymers; Properties and characterization; Small-angle neutron scattering; Gradient copolymer; Microphase separation; Small-angle neutron scattering; Viscoelasticity; Gelation; Temperature effect; Physical gel; Order disorder transformation; Experimental study; Mechanism; Small angle neutron scattering; Solution structure; Vinyl ether copolymer; Diblock copolymer; Aqueous solution; Comparative study; Concentrated solution
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2006.08.045

The small-angle neutron scattering investigation was carried out on semi-dilute aqueous solutions of block and gradient copolymers comprising pEOVE and pMOVE, pEOVE 300- block-pMOVE 300 (Block) and p(EOVE- grad-MOVE) 600 (Grad). Here, pEOVE and pMOVE denote poly(2-ethoxyethyl vinyl ether) and poly(2-methoxyethyl vinyl ether), respectively, and the numbers indicate the degrees of polymerization. The monomer composition in the Grad had a gradient along the polymer chain. For 20.0 wt% solutions, a microphase-separated structure and physical gelation were observed both in Block and in Grad systems. In the case of the Grad system, a gradual microphase separation took place as a function of temperature via a micellization with a small radius of core, characterized by the “reel-in” process, i.e., a winding of polymer chains to the core of a micelle because of the gradient composition. On the other hand, the Block system underwent a stepwise transition with respect to temperature. The relationship between microphase separation and the rheological behavior is explained from the viewpoint of microscopic structure.