Conformational transition and its dynamics of naphthalene-labeled poly (octadecyl vinyl ether) chains in dichloromethane solution

To investigate the influence of molecular structure such as side chain on phase separation process in solution, naphthalene-labeled poly (octadecyl vinyl ether) (PODVE) with long side chains was synthesized by living cationic polymerization. Rayleigh Light scattering (RLS) and photoluminescence (PL) studies indicated that side chain played a dominant role in phase separation process in PODVE/dichloromethane system. According to the results of RLS and PL spectra, it was found that PODVE chains changed from expanded coils to collapsed globules and then aggregated. At C = 0.2 g/L, the long side chain of PODVE (102) separated out from nonpolar solvent below 7.2 °C, which directly caused phase separation in solution. In addition, the phase separation temperature slightly increased when the concentration of PODVE (102) solution varies from 0.05 g/L to 0.2 g/L, and more obviously (i.e., from 3.5 °C to 7.2 °C) as the molecular weight increases from 4300 to 10 200. The Activation energy of phase separation of the PODVE solution was −270.09 kJ/mol estimated by means of Avrami equation and Arrhenius formula.