Cooperative preassociation stages of PEO-PPO-PEO triblock copolymers: NMR and theoretical study.

摘要: Using 1H and 13C 1D 2D NMR spectra, pulsed field-gradient (PFG) diffusion measurements, relaxations supported by density functional theory (DFT) calculations, the temperature-dependent behavior of (EO)m(PO)n(EO)m block copolymers (m/n = 31/14, 31/72, 17/1) in D2O below at critical micellar temperature (CMT) was investigated order to understand nature primary self-association acts their true driving force. It shown that a conformation change PO followed mild reversible association with other blocks eventually inner parts EO starts temperatures 10−12 K CMT. The process is entropy-driven disintegration PPO hydration envelope based on cooperation hydrophobic hydrogen bonding. partial dehydration its change. Both processes are cooperative correlation time 0.01 s an activation energy 51.3 kJ/mol. ...