title: Tuning of the temperature window for unit-cell and pore-size enlargement in face-centered-cubic large-mesopore silicas templated by swollen block copolymer micelles.
abstract: The unit-cell size and pore diameter as functions of temperature are investigated in the syntheses of FDU-12 silicas with face-centered cubic structure templated by Pluronic (PEO-PPO-PEO) block copolymer micelles swollen by toluene. The temperature range in which the unit-cell size and pore size strongly increase as temperature decreases is correlated with the critical micelle temperature (CMT) of the surfactant. While Pluronic F127 affords a wide range of unit-cell parameters (28-51 nm) and pore diameters (16-32 nm), it renders moderately enlarged pore sizes at 25 °C. The use of Pluronic F108 with higher CMT affords FDU-12 with very large unit-cell size (∼49 nm) and large pore diameter (27 nm) at 23 °C. Large unit-cell size (40-41 nm) and pore size (22 nm) were obtained even at 25 °C. The application of Pluronics F87 and F88 with much smaller molecular weights and higher CMTs also allows one to synthesize FDU-12 with quite large unit-cell parameters and pore sizes at room temperature. The present work demonstrates that one can judiciously select Pluronic surfactants with appropriate CMT to shift the temperature range in which the pore diameter is readily tunable.
authors.affiliation: Department of Chemistry, College of Staten Island and Graduate Center, City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314 (USA).|Current address: Agilent Technologies, 2850 Centerville Rd, Wilmington, DE 19808 (USA).
authors.forename: Yingyu
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Chemistry, College of Staten Island and Graduate Center, City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314 (USA).
authors.forename: Jinhui
authors.initials: J
authors.lastname: Yi
authors.affiliation: Department of Chemistry, College of Staten Island and Graduate Center, City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314 (USA). Michal.Kruk@csi.cuny.edu.
authors.forename: Michal
authors.initials: M
authors.lastname: Kruk
keywords: critical micelle temperature; mesopore size adjustment; ordered mesoporous silica; surfactant templating; swelling agent