TY  - JOUR
A1  - Hwang, Jongkook
A1  - Walczak, Ralf
A1  - Oschatz, Martin
A1  - Tarakina, Nadezda
A1  - Schmidt, Bernhard V. K. J.
T1  - Micro-Blooming: Hierarchically Porous Nitrogen-Doped Carbon Flowers Derived from Metal-Organic Mesocrystals
JF  - Small
N2  - Synthesis of 3D flower-like zinc-nitrilotriacetic acid (ZnNTA) mesocrystals and their conformal transformation to hierarchically porous N-doped carbon superstructures is reported. During the solvothermal reaction, 2D nanosheet primary building blocks undergo oriented attachment and mesoscale assembly forming stacked layers. The secondary nucleation and growth preferentially occurs at the edges and defects of the layers, leading to formation of 3D flower-like mesocrystals comprised of interconnected 2D micropetals. By simply varying the pyrolysis temperature (550-1000 degrees C) and the removal method of in the situ-generated Zn species, nonporous parent mesocrystals are transformed to hierarchically porous carbon flowers with controllable surface area (970-1605 m(2) g(-1)), nitrogen content (3.4-14.1 at%), pore volume (0.95-2.19 cm(3) g(-1)), as well as pore diameter and structures. The carbon flowers prepared at 550 degrees C show high CO2/N-2 selectivity due to the high nitrogen content and the large fraction of (ultra)micropores, which can greatly increase the CO2 affinity. The results show that the physicochemical properties of carbons are highly dependent on the thermal transformation and associated pore formation process, rather than directly inherited from parent precursors. The present strategy demonstrates metal-organic mesocrystals as a facile and versatile means toward 3D hierarchical carbon superstructures that are attractive for a number of potential applications.
KW  - 3D flower superstructures
KW  - hierarchically porous carbon
KW  - metal-organic mesocrystals
KW  - thermal transformation mechanism
Y1  - 2019
U6  - https://doi.org/10.1002/smll.201901986
SN  - 1613-6810
SN  - 1613-6829
VL  - 15
IS  - 37
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Lee, Hui-Chun
A1  - Hwang, Jongkook
A1  - Schilde, Uwe
A1  - Antonietti, Markus
A1  - Matyjaszewski, Krzysztof
A1  - Schmidt, Bernhard V. K. J.
T1  - Toward ultimate control of radical polymerization
BT  - functionalized metal-organic frameworks as a robust environment for Metal-Catalyzed Polymerizations
JF  - Chemistry of materials : a publication of the American Chemical Society
N2  - Herein, an approach via combination of confined porous textures and reversible deactivation radical polymerization techniques is proposed to advance synthetic polymer chemistry, i.e., a connection of metal-organic frameworks (MOFs) and activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). Zn-2(benzene-1,4-dicarboxylate)2(1,4-diazabicyclo[2.2.2]-octane) [Zn-2(bdc)(2)(dabco)] is utilized as a reaction environment for polymerization of various methacrylate monomers (methyl, ethyl, benzyl, and isobornyl methacrylate) in a confined nanochannel, resulting in polymers with control over dispersity, end functionalities, and tacticity with respect to distinct molecular size. To refine and reconsolidate the compartmentation effect on polymer regularity, initiator-functionalized Zn MOF was synthesized via cocrystallization with an initiator-functionalized ligand, 2-(2-bromo-2-methylpropanamido)-1,4-benzenedicarboxylate (Brbdc), in different ratios (10%, 20%, and 50%). Through the embedded initiator, surface-initiated ARGET ATRP was directly initiated from the walls of the nanochannels. The obtained polymers had a high molecular weight up to 392 000. Moreover, a significant improvement in end-group functionality and stereocontrol was observed, entailing polymers with obvious increments in isotacticity. The results highlight a combination of MOFs and ATRP that is a promising and universal methodology to prepare various polymers with high molecular weight exhibiting well-defined uniformity in chain length and microstructure as well as the preserved chain-end functionality.
Y1  - 2018
U6  - https://doi.org/10.1021/acs.chemmater.8b00546
SN  - 0897-4756
SN  - 1520-5002
VL  - 30
IS  - 9
SP  - 2983
EP  - 2994
PB  - American Chemical Society
CY  - Washington
ER  -