Abstract
The phase transitions of aqueous solutions of poly( N, N-diethylacrylamide-co-acrylic acid) (DEAAm–AA) were studied by micro-differential scanning calorimetry (DSC) and UV–visible spectrophotometry. The lower critical solution temperatures (LCST) obtained from the maxima of the first derivatives of the DSC and optical transition curves were in good agreement. The LCST values of the copolymers varied with the AA content. The optical transitions of the copolymers were wavelength dependent and were much broader than that of the homopolymer PDEAAm. It is reasoned that the AA copolymers formed smaller aggregates compared to the homopolymer PDEAAm. The stability of the smaller particles is attributed to the electrostatic repulsion among the partially ionized carboxylic groups in the copolymers. The LCST values were slightly concentration dependent in the relatively narrow concentration range studied. The enthalpy change ΔH for the phase transition in solution was found to be lower for the copolymer than that for the homopolymer PDEAAm.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
