High performance transparent polyimides by controlling steric hindrance of methyl side groups

2019 ◽  
Vol 120 ◽  
pp. 109235 ◽  
Author(s):  
Qi Wu ◽  
Xiaoru Ma ◽  
Feng Zheng ◽  
Xuemin Lu ◽  
Qinghua Lu
Keyword(s):  
Steric Hindrance ◽  
High Performance

Administration of the D-A structure and steric hindrance effect to construct efficient red emitters for high-performance OLEDs with low efficiency roll-off

2021 ◽  
Vol 192 ◽  
pp. 109398
Author(s):  
Guan-Yu Ding ◽  
Chun-Xiu Zang ◽  
Han Zhang ◽  
Zhong-Min Su ◽  
Guang-Fu Li ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Performance ◽  
Low Efficiency

scholarly journals A Novel Organic–Inorganic Hybrid Admixture for Increasing Flowability and Reducing Viscosity of Ultra-High Performance Paste

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3385 ◽  
Author(s):  
Min Wang ◽  
Hao Yao
Keyword(s):  
Steric Hindrance ◽  
High Performance ◽  
High Performance Concrete ◽  
High Viscosity ◽  
Inorganic Hybrid ◽  
Oh Groups ◽  
Low Viscosity ◽  
Binder Ratio ◽  
The One ◽  
Water Binder Ratio

The low flowability and high viscosity of ultra-high performance concrete (UHPC), which is mainly caused by the silica fume (SF) agglomeration and low water–binder ratio, is a severe defect in its engineering applications. Herein, a novel organic–inorganic hybrid (OIH) admixture was synthesized by grafting comb-like polycarboxylate ether (PCE) onto the surface of SF. On the one hand, PCE-grafting could effectively prevent SF agglomeration and improve the dispersion of SF core. The reason being the consumption of polar silicon hydroxyl (Si-OH) groups on the surface of SF and the steric hindrance effect generated from PCE arms. On the other hand, OIH admixture could adsorb onto the surface of cement and SF particles by electrostatic interaction, exhibiting stronger steric hindrance effect than traditional comb-like PCE. As a result, UHPC system with this star-like OIH admixture presented high flowability and low viscosity at low water–binder ratio (0.18).

High-performance nonfused ring electron acceptor with a steric hindrance induced planar molecular backbone

2022 ◽  
Author(s):  
Hao Lu ◽  
Xiaodong Wang ◽  
Hang Wang ◽  
Andong Zhang ◽  
Xinming Zheng ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Steric Hindrance ◽  
High Performance ◽  
Molecular Backbone

High-performance OLEDs based on 4,5-diaza-9,9′-spirobifluorene ligated rhenium(I) complex with enhanced steric hindrance

2012 ◽  
Vol 13 (12) ◽  
pp. 3138-3144 ◽  
Author(s):  
Xiao Li ◽  
Hai-Jun Chi ◽  
Gong-Hao Lu ◽  
Guo-Yong Xiao ◽  
Yan Dong ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Performance

Accessibility of hydroxyl groups in anhydride modified wood as measured by deuterium exchange and saponification

Holzforschung ◽  
2017 ◽  
Vol 72 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Greeley Beck ◽  
Sarah Strohbusch ◽  
Erik Larnøy ◽  
Holger Militz ◽  
Callum Hill
Keyword(s):  
Cell Wall ◽  
Steric Hindrance ◽  
High Performance ◽  
Radiata Pine ◽  
Deuterium Exchange ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Weight Percentage ◽  
Water Accessibility ◽  
Responsible Mechanism

AbstractAcetylated wood (WAc) shows improved properties largely due to the reduced amount of water in its cell wall, but the exact mechanism of water reduction remains unclear. Acetylation reduces hydroxyl (OH) content by acetyl (Ac) substitution but may also limit water access to unmodified OH groups by steric hindrance. In the present work, the accessibility of OH groups in acetylated or propionylated Radiata pine (Pinus radiataD. Don) wood (WAcand WPr) was investigated by deuterium exchange, saponification in sodium hydroxide followed by high-performance liquid chromatography (HPLC) analysis and weight percentage gain determination of the modified samples. Acetylation reduced OH accessibility (OHA) to a greater extent than would be predicted, if OH substitution were the only responsible mechanism for accessibility reduction. The combination of deuterium exchange and saponification results provides strong evidence that steric hindrance plays a key role in reduction of water accessibility to unmodified OH groups in WAc. The supramolecular architecture of WPrsamples seems to be modified by the propionylation reaction, which leads to increased OHAat low levels of substitution. This suggests that molecular restructuring within the cell wall exposes new OH groups after propionylation. At higher levels of substitution, however, the WPrexhibited less OHAthan expected indicating steric hindrance from the propionyl groups.

Sublimable cationic iridium(iii) complexes with large steric hindrance for high-performance organic light-emitting diodes

2019 ◽  
Vol 48 (26) ◽  
pp. 9669-9675 ◽  
Author(s):  
Ruihuan Liu ◽  
Dongxin Ma ◽  
Chen Zhang ◽  
Lian Duan
Keyword(s):  
Steric Hindrance ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Highly Efficient ◽  
Organic Light

Highly efficient sublimable cationic iridium(iii) complexes with bulky ancillary and major ligands.

scholarly journals Control of Shape and Size in Iron Fluoride Porous Sub-Microspheres: Consequences for Steric Hindrance Interaction

2021 ◽  
Vol 3 ◽  
Author(s):  
Weibing Song ◽  
Hongyu Lu ◽  
Wenlong Zhao ◽  
Xiaofei Cao ◽  
Lei Yan ◽  
...  
Keyword(s):  
Porous Structure ◽  
Steric Hindrance ◽  
Structural Control ◽  
High Performance ◽  
Retention Rate ◽  
Rate Capability ◽  
Peg 400 ◽  
Excellent Electrochemical Performance ◽  
Remaining Capacity ◽  
Iron Based

Iron-based fluorides are promising alternates for advanced sodium-free battery cathodes due to their large theoretical capacity. However, the rational structural control on the iron-based fluorides toward high-performance batteries is still challenging. To this end, a controllable porous structure on FeF3·0.33H2O sub-microspheres is achieved by a polyethylene glycol (PEG)-assisted hydrothermal method via adjusting the volume of PEG-400. Experimental and molecular dynamic results verify that the formation of small amethyst-like sub-microspheres is mainly ascribed to the steric hindrance reaction of PEG-400, which makes it difficult for F− to combine with Fe3+ to form coordination bonds, and partially hinders the nucleation and growth of FeF3·0.33H2O nanospheres. As a sodium-free battery cathode, the FeF3·0.33H2O sub-microspheres with porous structure and smaller particle size exhibit excellent electrochemical performance with regard to cycle capacity and rate capability (a remaining capacity of 328 mAh g−1 and up to 95.3% retention rate when backs to 0.1 C after 60 cycles).

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