Unraveling poloxamer 237 structure and dynamics by DSC and solid-state NMR

SALOMON, CJ.; PRIOTTI, J.; LEONARDI, D.; ORLANDI, SC.; NUNES, TG.; DIOGO, H.

Lisboa

Congreso; VIII Ibero-American NMR Meeting; 2018

Poloxamers (PLXs) are non-ionic tri-block semi-crystalline copolymers that contain one hydrophobic chain (polypropylene glycol, PPG) connected to two hydrophilic chains (polyethylene glycol, PPG). PLXs are available with various molecular weights and relative proportions of EG versus PG units. Due to their surfactant properties, PLXs have been widely employed from pharmacology to food science. Recently, we have investigated the impact of PLX 237 and poly(vinylpyrrolidone) over praziquantel recrystallization and dissolution 1. Aiming to unravel PLX 237 structure and dynamics, DSC and solid-state NMR studies were performed. The glass transition and the melting temperatures of PLX 237 were detected at 61ºC and 49ºC, respectively, as they are the thermal signatures expected for a semi-crystalline copolymer. Then, based on spectral elucidation and relaxation measurements, PLX domains with different mobility were assigned. For example, large differences in the time constants for the 13C magnetization build-up under CP and in HT1 values were obtained between PPG and PEG components. These and other data correlate well with PG and EG being identified as the PLX amorphous and crystalline components, respectively, as shown for the first time using solid-state NMR.