Hollow mesoporous organosilica nanospheres templated with flower-like micelles of pentablock copolymers

Eun-Bum Cho; Eunji Choi; Shu Yang; Mietek Jaroniec

doi:10.1016/j.jcis.2018.05.076

Hollow mesoporous organosilica nanospheres templated with flower-like micelles of pentablock copolymers

J Colloid Interface Sci. 2018 Oct 15:528:124-134. doi: 10.1016/j.jcis.2018.05.076. Epub 2018 May 22.

Authors

Eun-Bum Cho¹, Eunji Choi², Shu Yang³, Mietek Jaroniec⁴

Affiliations

¹ Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea. Electronic address: echo@seoultech.ac.kr.
² Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea.
³ Department of Materials Science and Engineering, University of Pennsylvania, PA 08826, United States.
⁴ Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, United States. Electronic address: jaroniec@kent.edu.

PMID: 29843060
DOI: 10.1016/j.jcis.2018.05.076

Abstract

We present a facile preparation of hollow mesoporous organosilica nanospheres with well-defined, uniform mesopores by controlling the morphology of pentablock copolymer templates under acidic conditions. The CBABC type poly(lactic acid-co-glycolic acid)-b-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(lactic acid-co-glycolic acid) (PLGA-b-PEO-b-PPO-b-PEO-b-PLGA) pentablock copolymers were synthesized via a step-growth and ring-opening polymerization method using Pluronic F68 and F108 as macro-initiators. Two kinds of pentablock copolymers, (LA₄₅GA₁₂)EO₇₅PO₃₀EO₇₅(LA₄₅GA₁₂) and (LA₂₈GA₉)EO₁₄₁PO₅₄ EO₁₄₁(LA₂₈GA₉), were used as single soft templates to prepare mesoporous ethane-silica and benzene-silica hollow nanospheres by sol-gel chemistry in acidic aqueous solutions. The inner cavity diameter was controlled up to ∼20 nm by varying acidity and the chain length of the hydrophobic PLGA block without using additional swelling agents. The evolution of hollow nanospheres could be explained by single flower-like micelle template mechanism and the variation of morphology of pentablock copolymers upon solution acidity. Moreover, the amine-functionalized hollow benzene-silica nanospheres showed high carbon dioxide adsorption at ambient conditions. The hollow organosilica nanospheres were characterized by small-angle X-ray scattering, nitrogen adsorption-desorption, solid-state ¹³C- and ²⁹Si nuclear magnetic resonance, and scanning and transmission electron microscopy and so on.

Keywords: Flower-like micelle; Hollow nanosphere; Large mesopore; Mesoporous organosilica; Pentablock copolymer.