Synthesis and Properties of Ionically Modified Polymers with LCST Behavior

• Published in: Macromolecules Vol. 31; no. 17; pp. 5616 - 5623
• Main Authors: Hahn, Mathias, Görnitz, Eckhard, Dautzenberg, Herbert
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 25.08.1998
• Subjects: Applied sciences; Copolymerization; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Preparation, kinetics, thermodynamics, mechanism and catalysts; Solvent effect; Ionomer; Quaternary ammonium copolymer; Second virial coefficient; Acrylamide derivative copolymer; Experimental study; Sedimentation coefficient; Sulfonate copolymer; Cloud point; Mixed solvent; Ionic strength; Preparation; Time curve; Acrylate copolymer; Molecular aggregation; Methacrylate copolymer; Aqueous solution; Radical copolymerization; Saline solution; Carboxylate copolymer; Comparative study; Conformational transition
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma9800010

Ionically modified LCST polymers were synthesized by free radical copolymerization of N-isopropylacrylamide (NIPAM) with various cationic, anionic, and amphoteric comonomers, resulting in products with comparable molecular masses and charge concentrations. The temperature-dependent phase transition behavior of the copolymers was investigated in water, aqueous sodium chloride solutions, and mixtures of water with dimethylformamide (DMF) using light transmission measurements, static light scattering, viscometry, and sedimentation experiments in an analytical ultracentrifuge. The LCST of the cationic modified copolymers remains unchanged compared with the homopolymer, but it is increased as a result of an amphoteric or anionic modification. Phase transitions are accompanied by conformational changes followed by aggregation processes. These changes are enhanced in the presence of salt. The phase transition of poly-NIPAM-co-MADAMBQ ((methacryloyloxy)ethyl)dimethylbenzylammonium chloride) in 0.5 M NaCl was studied in detail investigating the temperature dependence of molecular parameters as intrinsic viscosity, particle mass, radius of gyration, second virial coefficient, and sedimentation coefficient.