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  - Al Nakeeb, Noah
A1  - Kochovski, Zdravko
A1  - Li, Tingting
A1  - Zhang, Youjia
A1  - Lu, Yan
A1  - Schmidt, Bernhard V. K. J.
T1  - Poly(ethylene glycol) brush-b-poly(N-vinylpyrrolidone)-based double hydrophilic block copolymer particles crosslinked via crystalline alpha-cyclodextrin domains
JF  - RSC Advances
N2  - Self-assembly of block copolymers is a significant area of polymer science. The self-assembly of completely water-soluble block copolymers is of particular interest, albeit a challenging task. In the present work the self-assembly of a linear-brush architecture block copolymer, namely poly(N-vinylpyrrolidone)-b-poly(oligoethylene glycol methacrylate) (PVP-b-POEGMA), in water is studied. Moreover, the assembled structures are crosslinked via alpha-CD host/guest complexation in a supramolecular way. The crosslinking shifts the equilibrium toward aggregate formation without switching off the dynamic equilibrium of double hydrophilic block copolymer (DHBC). As a consequence, the self-assembly efficiency is improved without extinguishing the unique DHBC self-assembly behavior. In addition, decrosslinking could be induced without a change in concentration by adding a competing complexation agent for alpha-CD. The self-assembly behavior was followed by DLS measurement, while the presence of the particles could be observed via cryo-TEM before and after crosslinking.
Y1  - 2019
U6  - https://doi.org/10.1039/c8ra10672j
SN  - 2046-2069
VL  - 9
IS  - 9
SP  - 4993
EP  - 5001
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -