RT info:eu-repo/semantics/article
T1 Thermally rearranged (TR) polybenzoxazoles from o‑substituted prTecursor polyimides with phenyl pendant groups: synthesis, properties, and thermal rearrangement conditions
A1 Rojas Rodríguez, Mario
A1 Rico Martínez, Sandra
A1 Prádanos del Pico, Pedro Lourdes
A1 Álvarez, Cristina
A1 Alexandrova, Larissa
A1 Moo Lee, Young
A1 Lozano, Ángel E.
A1 Aguilar Lugo, Carla
K1 Poliimidas
K1 Poliimidas
K1 Polibenzoxazoles
K1 Fenilo
K1 2210 Química Física
AB A series of polyimides (PIs) was synthesized from 6FDA and two o-OH substituted diamines having bulky pendant phenyl, Ph, and trifluoromethyl, CF3, groups as precursors for thermally rearranged polybenzoxazole, TR-PBO, membranes. One diamine had two pendant Ph substituents; in the other, the substituents were Ph and CF3. Applying azeotropic and chemical cyclizations allowed the obtention of four o-hydroxy (o-OH) or/and o-acetoxy (o-OAc) substituted PIs depending on the imidization method. The PIs were labeled as 3Ph-OH, 4Ph-OH, or 3Ph-OAc and 4PH-OAc, respectively. Thermal rearrangements of all four precursors were investigated in the interval from 350 to 450 °C. The conversions to TR-PBO increased with temperature, and almost quantitative conversions were obtained at temperatures close to 450 °C, although o-OH substituted PIs reached conversions slightly higher than those of o-OAc PIs at a given temperature. The TR-polymers’ fractional free volume (FFV) also increased with conversion but was higher for the o-OAc substituted precursors. Despite the high TR-PBO conversions, self-supported uniform TR membranes with reasonable mechanical properties were obtained, except for 4Ph-OH. Gas separation behavior of the membranes significantly improved after the thermal treatment, and the final CO2/CH4 permselectivities lay between the 1991 and 2008 Robeson upper bounds. Particularly, TR-membranes derived from o-OAc precursors and with pendant CF3 group demonstrated better gas transport properties with values of P(CO2) = 1121 barrer and αCO2/CH4 = 29 for 3Ph-OAc derived membrane, which positioned it beyond the 2008 upper limit.
PB ACS
SN 0024-9297
YR 2024
FD 2024
LK https://uvadoc.uva.es/handle/10324/70926
UL https://uvadoc.uva.es/handle/10324/70926
LA eng
NO Macromolecules, Agosto 2024, vol. 57, n. 16. p. 8187–8201
NO Producción Científica
DS UVaDOC
RD 20-nov-2024