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155 results on '"Peng, Chi‐How"'

4. Reversible-Deactivation Radical Polymerization of Vinyl Monomers Mediated by Schiff Bases

Author

Benchaphanthawee, Wachara, Yang, Zhe-Wei, Hsu, Huei-Ting, and Peng, Chi-How

Abstract

N,N′-Bis(salicylidene)-1,2-phenylenediamine (salophen), a versatile ligand for organometallics, was found to be capable of mediating the reversible-deactivation radical polymerization (RDRP) of vinyl acetate (VAc) and N-vinylpyrrolidone (NVP) with predictable molecular weights and the formation of block copolymers. The mechanism was first studied via the substituent effect with different salophen derivatives and then rationalized by density functional theory (DFT) calculations associated with the control studies and chain-end characterization. We discovered that the radicals react with the imine carbon of salophen to generate an active species that further deactivates the propagating radicals to form the dormant species. The observed living characteristics were attributed to the equilibrium between the dormant species and the active species with radicals.

Published
2025
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6. A Concise Route to Keto‐Bridged Polyphenols by Photo‐Fries Rearrangement in Flow.

Author

Lin, Xin‐Jie, Wang, Chien‐Lung, Peng, Chi‐How, Liu, Hsueh‐Ju, and Wu, Yen‐Ku

Subjects
POLYPHENOLS, LIGANDS (Chemistry), PLANT polyphenols, PHENOL
Abstract

Described is a new synthetic route to bis(2‐hydroxy‐3,5‐di‐t‐butylphenyl)methanone and its derivatives. The combined esterification/photo‐Fries rearrangement approach enables a modular preparation of keto‐bridged polyphenols. This protecting group‐free process is highly atom‐ and step‐economic, and a scalable production was easily achieved in the continuous‐flow mode. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Photocatalyzed dimethylacrylamide polymerization in an aqueous solution using 4-nitrophenylacetylene-modified Cu2O crystals.

Author

Chen, Yu-Chien, Huang, Xing-Fu, Hsu, Huei-Ting, Wu, Er-Ting, Peng, Chi-How, and Huang, Michael H.

Abstract

Cu2O cubes, octahedra, and rhombic dodecahedra with and without surface 4-nitrophenylacetylene (4-NA) functionalization were used to catalyze dimethylacrylamide (DMA) photopolymerization in water. Among these samples, the 4-NA-modified Cu2O cubes presented a highest monomer conversion percentage of 69% after 1 h of 420 nm light irradiation, possibly due to the most efficient electron transfer from the particles to the Ph2ICl co-initiator. The synthesized polymers generally have high molecular weights and good dispersity values. The reaction can be easily scaled up 10 fold under room light. After simple particle removal, a transparent gel-like polymer product is obtained. The Cu2O crystals can be recycled for use in more polymerization reactions. Electron and hole scavenging experiments were conducted to support the proposed reaction mechanism. This work shows surface-controlled semiconductor nanocrystals can be simple yet highly effective photocatalysts for some polymerization reactions. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Versatile cobalt(Salen‐NEt2) for aqueous cobalt‐mediated radical polymerization.

Author

Chang, I‐Hsiang, Lu, Hung‐Hsun, Ping, Hsin, Chang, Chun‐Wei, and Peng, Chi‐How

Subjects
RADICALS (Chemistry), VINYL acetate, BLOCK copolymers, GEL permeation chromatography, POLYMERIZATION, COBALT
Abstract

Cobalt‐mediated radical polymerization (CMRP) has enabled the polymerization of a wide range of monomers with predictable molecular parameters and well‐defined compositions and architectures. However, the synthesis of hydrophilic polymers by CMRP directly in the aqueous phase is still challenging. Herein, a handy cobalt complex was developed to perform CMRP of N‐vinylpyrrolidone (NVP), 2‐hydroxyethyl acrylate (HEA), and N,N‐dimethylacrylamide (DMA) with linearly increased molecular weight, low polydispersity values, and smoothly shifted gel permeation chromatography (GPC) traces. The chain extensions of NVP, HEA, and DMA revealed the well chain‐end fidelity for the synthesis of block copolymers. Moreover, the poly(N‐vinylpyrrolidone)‐block‐poly(vinyl acetate) (PVP‐b‐PVAc) amphiphilic block copolymer colloidal solution was achieved directly in aqueous phase by cobalt‐mediated radical polymerization‐induced self‐assembly (CMR‐PISA), forming the nanoparticles consisting of a hydrophilic PVP corona and a hydrophobic PVAc core. This new mediator opens the opportunity for the synthesis of various hydrophilic (co)polymers in an environmentally friendly manner. [ABSTRACT FROM AUTHOR]

Published
2023
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18. Amorphous flexible covalent organic networks containing redox-active moieties: a noncrystalline approach to the assembly of functional molecules† †Electronic supplementary information (ESI) available: Experimental methods, summary of previous studies, TG curves, 13C NMR spectra, molecular structures, UV-Vis-NIR spectra, SEM, AFM, and TEM images, CV curves, and reproducibility of the electrochemical properties. See DOI: 10.1039/d0sc01757d

Author

Suzuki, Jumpei, Ishizone, Akira, Sato, Kosuke, Imai, Hiroaki, Tseng, Yu-Jen, Peng, Chi-How, and Oaki, Yuya

Subjects
Chemistry
Abstract

Amorphous flexible covalent organic networks containing functional molecules were synthesized by consecutive and multiple reactions at different rates and in multiple directions., The organization states of functional molecules have a significant impact on the properties of materials. A variety of approaches have been studied to obtain well-organized molecular assemblies. The present work shows a new non-organized state of isolated and dispersed functional molecules in amorphous flexible covalent organic networks. Redox-active quinone molecules are embedded in the amorphous network polymers. Consecutive reactions between benzoquinone (BQ) and linker molecules generate random network structures through polymerization at different rates and in multiple directions. The low-crystalline stackings of the amorphous network polymers facilitate the formation of nanoflakes through exfoliation in dispersion media. Enhanced electrochemical performances, one of the highest specific capacities in recent studies, were achieved by efficient redox reactions of the quinone moiety. The present noncrystalline approach, low-crystalline stacking of designer amorphous covalent organic networks, can be applied to construct similar nanostructured polymer materials containing functional units.

Published
2020

20. Versatile cobalt(Salen‐NEt2) for aqueous cobalt‐mediatedradical polymerization

Author

Chang, I‐Hsiang, Lu, Hung‐Hsun, Ping, Hsin, Chang, Chun‐Wei, and Peng, Chi‐How

Abstract

Cobalt‐mediated radical polymerization (CMRP) has enabled the polymerization of a wide range of monomers with predictable molecular parameters and well‐defined compositions and architectures. However, the synthesis of hydrophilic polymers by CMRP directly in the aqueous phase is still challenging. Herein, a handy cobalt complex was developed to perform CMRP of N‐vinylpyrrolidone (NVP), 2‐hydroxyethyl acrylate (HEA), and N,N‐dimethylacrylamide (DMA) with linearly increased molecular weight, low polydispersity values, and smoothly shifted gel permeation chromatography (GPC) traces. The chain extensions of NVP, HEA, and DMA revealed the well chain‐end fidelity for the synthesis of block copolymers. Moreover, the poly(N‐vinylpyrrolidone)‐block‐poly(vinyl acetate) (PVP‐b‐PVAc) amphiphilic block copolymer colloidal solution was achieved directly in aqueous phase by cobalt‐mediated radical polymerization‐induced self‐assembly (CMR‐PISA), forming the nanoparticles consisting of a hydrophilic PVP corona and a hydrophobic PVAc core. This new mediator opens the opportunity for the synthesis of various hydrophilic (co)polymers in an environmentally friendly manner. A new water‐soluble cobalt(II) complex, CoII(Salen‐NEt2), has been developed to mediate the aqueous radical polymerization of N‐vinylpyrrolidone (NVP), 2‐hydroxyethyl acrylate (HEA), and N,N‐dimethylacrylamide (DMA) with the living characteristics of the linearly increased molecular weight and the formation of block copolymers. With the chain extension from PNVP to PVAc, the cobalt‐mediated radical polymerization‐induced self‐assembly (CMR‐PISA) could be achieved.

Published
2023
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41. Macromol. Rapid Commun. 24/2016

Author

Chi, Mu-Huan, primary, Su, Chun-Hsien, additional, Cheng, Ming-Hsiang, additional, Chung, Pei-Yun, additional, Peng, Chi-How, additional, and Chen, Jiun-Tai, additional

Published
2016
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43. Macromol. Chem. Phys. 3/2016

Author

Wang, Fu-Sheng, primary, Yang, Tsung-Yao, additional, Hsu, Ching-Chun, additional, Chen, Ya-Jo, additional, Li, Ming-Han, additional, Hsu, Yu-Jie, additional, Chuang, Min-Chieh, additional, and Peng, Chi-How, additional

Published
2016
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44. Highly Stretchable Free-Standing Poly(acrylic acid)-block-poly(vinyl alcohol) Films Obtained from Cobalt-Mediated Radical Polymerization

Author

Wang, Fu-Sheng, Wang, Tzu-Fang, Lu, Hung-Hsun, Ao-Ieong, Wai-Sam, Wang, Jane, Chen, Hsin-Lung, and Peng, Chi-How

Abstract

The block copolymers of poly(acrylic acid)-b-poly(vinyl alcohol) (PAA-b-PVA) were obtained from the hydrolysis of poly(methyl acrylate)-b-poly(vinyl acetate) (PMA-b-PVAc), which was synthesized by cobalt-mediated radical polymerization (CMRP) using the cobalt(II) porphyrin complex (CoII(TMP)) as the mediator. The mechanical properties of the PAA-b-PVA free-standing films could be tuned by the pH of the aqueous solution used to cast the films. The block copolymer films showed a much higher tensile strain and fractural tensile strength than the films prepared from the blends of PAA and PVA homopolymers. FTIR and morphological characterizations suggested that the tensile properties of the films were governed by both the hydrogen bonding between PVA and PAA that led to interpolymer complexation and the phase-separated morphology. For a given type of material, the greater extent of interpolymer complexation attained at lower solution pH led to the film with better tensile properties. The difference in the length scale of phase separation was responsible for the large difference in the tensile properties between block copolymer and blend films, where the characteristic nanostructure formed in the block copolymer prescribed a considerably larger amount of interface which enhanced the tensile properties significantly.

Published
2024
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45. The Mechanism and Thermodynamic Studies of CMRP: Different Control Mechanisms Demonstrated by CoII (TMP), CoII (salen*), and CoII (acac)2 Mediated Polymerization, and the Correlation of Reduction Potential, Equilibrium Constant, and Control Mechanism

Author

Wang, Fu-Sheng, primary, Yang, Tsung-Yao, additional, Hsu, Ching-Chun, additional, Chen, Ya-Jo, additional, Li, Ming-Han, additional, Hsu, Yu-Jie, additional, Chuang, Min-Chieh, additional, and Peng, Chi-How, additional

Published
2015
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49. Macromol. Rapid Commun. 5/2015

Author

Ko, Hao-Wen, primary, Chi, Mu-Huan, additional, Chang, Chun-Wei, additional, Su, Chun-Hsien, additional, Wei, Tzu-Hui, additional, Tsai, Chia-Chan, additional, Peng, Chi-How, additional, and Chen, Jiun-Tai, additional

Published
2015
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