Article
Chemistry, Multidisciplinary
Xuejin Yang, Sean R. Gitter, Allison G. Roessler, Paul M. Zimmerman, Andrew J. Boydston
Summary: Research has found a simple method to control alkene stereochemistry in photoredox mediated metal-free ring-opening metathesis polymerization. Ion-pairing, initiator sterics, and solvation effects each have a profound impact on polynorbornene's stereochemistry. By adjusting reaction conditions, it is possible to control the cis or trans alkene content of PNB.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Phong K. Quach, Jesse H. Hsu, Ivan Keresztes, Brett P. Fors, Tristan H. Lambert
Summary: The ring-opening metathesis polymerization of cyclopropenes using hydrazonium initiators was investigated. The initiators, formed by condensing 2,3-diazabicyclo[2.2.2]octane and an aldehyde, polymerize cyclopropene monomers through a sequence of [3+2] cycloaddition and cycloreversion reactions. The study showed that the monomer to initiator ratio had a positive correlation with the degree of polymerization.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Review
Polymer Science
Dmytro Ryzhakov, Gael Printz, Beatrice Jacques, Samir Messaoudi, Francoise Dumas, Samuel Dagorne, Franck Le Bideau
Summary: Polyester synthesis through eco-friendly methods is a major challenge today, with metal complexes playing a crucial role as catalysts and initiators in the process. The use of metal-free organo-catalysts/initiators remains to be explored, with interesting developments reported over the past five years. This area of organo-catalyzed/initiated processes is still in its infancy but holds great potential for further advancements.
Article
Chemistry, Analytical
Xin Zhu, Zenghui Liu, Jinge Li, Zutian Li, Fuchun Si, Huaixia Yang, Jinming Kong
Summary: In this study, a novel electrochemical sensor was developed for highly sensitive detection of exosomes secreted by lung cancer cells, utilizing polysaccharide-initiated ring-opening polymerization and click polymerization. The sensor exhibited a good linear relationship, low detection limit, as well as advantages of high specificity and anti-interference.
Article
Polymer Science
Watcharee Funfuenha, Winita Punyodom, Puttinan Meepowpan, Wanich Limwanich
Summary: Microwave irradiation was successfully used to improve the solvent-free ring-opening polymerization of ε-caprolactone with different n-butyltin(IV) chloride initiators. The performance of these initiators was compared to the conventional tin(II) 2-ethylhexanoate. The presence of chlorine atom in the n-butyltin(IV) chloride initiators played a significant role in controlling the molecular weight of the polymer.
Review
Polymer Science
Chengjian Zhang, Xiaowei Geng, Xinghong Zhang, Yves Gnanou, Xiaoshuang Feng
Summary: Sensitivity to environmental concerns and the demand for metal-free polymeric materials have driven research towards breakthroughs in organocatalytic polymerizations. Triethyl borane (TEB) has been discovered as an exceptional Lewis acid, serving to generate ate complexes and activate epoxides. Lewis pairs consisting of alkyl boranes combined with onium salts or organic bases have demonstrated unprecedented versatility for (co)polymerizations of oxygenated monomers, producing various oxygenated polymers. This review summarizes the progress made in TEB-mediated polymerization systems and proposes future challenges in organocatalytic synthesis.
PROGRESS IN POLYMER SCIENCE
(2023)
Article
Polymer Science
Salvatore Impemba, Gabriele Manca, Irene Tozio, Stefano Milione
Summary: In this study, new zinc catalysts were developed using thioether-amide ligands for the ring-opening polymerization of cyclic esters. Experimental and theoretical studies provided insights into the parameters that influence catalytic activity. The catalysts exhibited high activity in the polymerization of rac-beta-butyrolactone and showed agreement with expected results in terms of molecular weight and polydispersity index.
Article
Polymer Science
Zhunxuan Li, Rui Chen, Ying Wang, Linlin Zhu, Wenyi Luo, Zhen Zhang, Nikos Hadjichristidis
Summary: An efficient synthetic methodology was developed for the modification of hyperbranched polyethyleneimines (PEI) using N-sulfonyl aziridines, resulting in materials with unique fluorescence properties and the ability to remove hazardous metals.
Article
Polymer Science
Zhengyang Liu, Jinfeng Shi, Na Zhao, Zhibo Li
Summary: In this study, polysiloxanes with unique low temperature flexibility, including polydiethylsiloxane (PDES) and poly(dimethylsiloxane-co-diethylsiloxane) (PMES) copolymers, were successfully synthesized. The cyclic trimeric phosphazene base (CTPB) catalyzed ring-opening polymerization (ROP) at room temperature, resulting in high yields of PDES homopolymers with high molecular weights. Furthermore, the random copolymers of PMES with tunable diethylsiloxane contents were directly prepared via ring-opening copolymerization (ROCP) using CTPB as a catalyst. The controlled copolymer composition and the random distribution of diethylsiloxane and dimethylsiloxane units were confirmed by microstructure characterizations. The thermal property investigations demonstrated the good low-temperature flexibility and thermal stability of PMES copolymers, indicating their potential in extreme environmental applications.
EUROPEAN POLYMER JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Meng Huo, Yawen Bian, Chunyang Yu, Gangsheng Tong, Chongyin Zhang, Xinyuan Zhu
Summary: This study presents an AROP method for N-sulfonyl aziridines that can be operated in air environment using sulfanions as initiators. Open-vessel polymerization resulted in a range of polymers with high livingness and narrow molecular weight distributions, enabling further post-polymerization functionalization.
SCIENCE CHINA-CHEMISTRY
(2021)
Article
Multidisciplinary Sciences
Yali Hu, Zi-You Tian, Wei Xiong, Dedao Wang, Ruichi Zhao, Yan Xie, Yu-Qin Song, Jun Zhu, Hua Lu
Summary: This study presents a water-assisted controlled ring-opening polymerization method for ProNCA, which enables the rapid synthesis of well-defined PLP in a short time. The use of water facilitates proton shift and lowers the energy barrier, leading to fast and efficient reactions. The protein-mediated ROP of ProNCA offers a convenient approach for the synthesis of various protein-PLP conjugates with enhanced properties.
NATIONAL SCIENCE REVIEW
(2022)
Article
Polymer Science
Yuliya A. Piskun, Evgenii A. Ksendzov, Anastasiya V. Resko, Mikhail A. Soldatov, Peter Timashev, Hongzhi Liu, Irina V. Vasilenko, Sergei V. Kostjuk
Summary: The bulk ring-opening polymerization of epsilon-caprolactone was studied using a phosphazene-containing porous polymeric material (HPCP) as the catalyst at high reaction temperatures (130-150 degrees). HPCP, in combination with benzyl alcohol as an initiator, enabled the controlled living ROP of epsilon-caprolactone, producing polyesters with controlled molecular weights up to 6000 g/mol and moderate polydispersity. Higher molecular weight poly(epsilon-caprolactone) was obtained at a lower temperature of 130 degrees C. The HPCP catalyst demonstrated high thermal and chemical stability, allowing for reuse in multiple cycles without significant loss in efficiency. A tentative mechanism involving the activation of the initiator through the basic sites of the catalyst was proposed.
Article
Polymer Science
Hans. R. Kricheldorf, Steffen M. Weidner
Summary: Alcohol-initiated ring-opening polymerizations of L-lactide were investigated, with variations in the alcohol nature, LA/initiator ratio, LA/SnOct2 ratio, and time. Neat SnOct2 exhibited catalytic activity in THF and some aromatic solvents, while its activity was strongly reduced in solvents like 1,3-dioxolane, dimethylformamide (DMF), and N-methyl pyrrolidone (NMP). The formation of cyclization was observed at 115°C in toluene but not at 70°C, which was attributed to the reduced mobility of the initially formed linear chains in toluene.
EUROPEAN POLYMER JOURNAL
(2023)
Article
Polymer Science
Sebla Onbulak, Marc A. Hillmyer
Summary: The synthesis of sequence-controlled poly(ethylene-co-styrene) copolymers is challenging due to limitations in catalytic olefin polymerizations. An alternative method using ROMP of cyclic olefins followed by hydrogenation can generate ethylene copolymers with regioregularity. Investigating the ROMP of low-strain cyclododecenes provided useful information for mechanistic aspects of polymerization.
Article
Polymer Science
Katherine J. Stawiasz, Chloe I. Wendell, Benjamin A. Suslick, Jeffrey S. Moore
Summary: The development of a photo-redox-initiated frontal ring-opening metathesis polymerization (FROMP) chemical system is reported. This system provides a well-controlled reaction front and extended pot life.
Article
Chemistry, Multidisciplinary
Naganath Patil, Senthil Bhoopathi, Vamshi Chidara, Nikos Hadjichristidis, Yves Gnanou, Xiaoshuang Feng
Article
Chemistry, Multidisciplinary
Mingchen Jia, Nikos Hadjichristidis, Yves Gnanou, Xiaoshuang Feng
Summary: The direct copolymerization of p-tosyl isocyanate with epoxides using onium salts and trialkylborane as initiators has been successfully demonstrated, producing polyurethanes without side products. This study holds the potential for developing new materials with unprecedented properties through terpolymerization with other oxygenated monomers and CO2.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Polymer Science
Vamshi K. Chidara, Senthil K. Boopathi, Nikos Hadjichristidis, Yves Gnanou, Xiaoshuang Feng
Summary: Poly(ester-carbonate) copolymers were synthesized by one-pot copolymerization of epoxides with anhydrides and CO2 activated by triethylborane (TEB). The feeding ratio of anhydrides to epoxides determined the structure of the copolymers, with random and tapered ester structures observed. Terpolymerizations and block copolymerizations were compared in terms of the obtained copolymers' structures and properties.
Article
Polymer Science
Prakash Alagi, George Zapsas, Nikos Hadjichristidis, Sung Chul Hong, Yves Gnanou, Xiaoshuang Feng
Summary: Brush-type macromolecules (BMs) have garnered significant attention in recent decades due to their unique properties and potential applications in nanoscience, drug delivery systems, and photonics. A two-step synthesis strategy was reported for the preparation of polycarbonate-grafted copolymers with either star-shaped or brush-typed morphologies using a grafting from approach, showing promising results in the synthesis of these novel materials.
Article
Chemistry, Multidisciplinary
Mingchen Jia, Dongyue Zhang, Yves Gnanou, Xiaoshuang Feng
Summary: Three types of copolymers with different carbonate content were prepared through copolymerization of ethylene oxide with CO2 under metal-free conditions using onium salts as initiators. The copolymerization process also allowed for the introduction of functional groups along the backbone of the copolymers and the generation of amphiphilic triblocks with different hydrophilic-hydrophobic balance. The properties of the copolymers were characterized by various analytical methods and their degradation behavior was investigated under different conditions.
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
(2021)
Article
Polymer Science
Chao Chen, Yves Gnanou, Xiaoshuang Feng
Summary: The ring-opening copolymerization of epoxides with isothiocyanates was explored for the first time. Various epoxides were copolymerized with aromatic and aliphatic ITCs, and the effects of different phosphazene bases, temperatures, and Lewis acids on the copolymerization were investigated. The thermal properties of the obtained copolymers were analyzed.
Article
Polymer Science
Jingjing Liu, Yves Gnanou, Xiaoshuang Feng
Summary: The value and merit of triethylborane (TEB)-based ate complexes for the synthesis of various oxygenated polymers have been demonstrated. This study expanded the scope of TEB-based initiating systems to anionically polymerize cyclic esters and to copolymerize them with propylene oxide (PO). The addition of hydrogen-bonding donors promoted a fast and controlled ring-opening polymerization (ROP) of cyclic esters. The controlled nature of the polymerization was confirmed by characterization techniques. These borane-based ate complexes showed great potential for the synthesis of copolymers.
Review
Polymer Science
Jiaxi Xu, Xin Wang, Jingjing Liu, Xiaoshuang Feng, Yves Gnanou, Nikos Hadjichristidis
Summary: Ring-opening polymerization (ROP) is a prevalent and convenient method for synthesizing well-defined polymers with initiators/catalysts. One of the challenges faced by ROP catalysts is the selective activation of functional groups or linkages of the monomer without those carried out in the polymer chains, especially at high conversion. H-bonding organocatalysts can offer precise selectivity for ROP in a wide range of monomers.
PROGRESS IN POLYMER SCIENCE
(2022)
Article
Polymer Science
Naganath Patil, Yves Gnanou, Xiaoshuang Feng
Summary: By adding Lewis acid such as triethylborane (TEB), the copolymerization of o-phthalaldehyde (OPA) with various epoxides has been successfully carried out under ambient conditions, resulting in the formation of polyacetals. The role and effect of TEB, its amount, and the feeding ratio of OPA to epoxides during their copolymerizations were investigated. The successful copolymerization was further extended to the synthesis of polyether-b-polyacetal block copolymers with different structure and properties.
Article
Polymer Science
Chao Chen, Yves Gnanou, Xiaoshuang Feng
Summary: In this study, a series of bifunctional borinane-based catalysts were successfully designed and synthesized for efficient ring-opening polymerization of epoxides under mild conditions, resulting in high molar mass polyethers. These catalysts showed high productivity even at low loading amounts, as low as 50 ppb, when used with chain transfer agents. Additionally, they demonstrated record turnover frequency (TOF) values and molar masses for the polymerization of oxetane.
Article
Polymer Science
Chao Chen, Yves Gnanou, Xiaoshuang Feng
Summary: We report the synthesis of commercially attractive low molar mass polycarbonate polyols obtained through CO2 and epoxide ring-opening copolymerization using borinane-based bifunctional organocatalysts and chain transfer agents. These catalysts exhibit high selectivity and productivity for both poly(cyclohexane carbonate) polyols and poly(ether propylene carbonate) polyols. The molar mass of the resulting polycarbonates can be precisely controlled, showing great potential for large-scale preparation of CO2-based polyols.
Review
Polymer Science
Chengjian Zhang, Xiaowei Geng, Xinghong Zhang, Yves Gnanou, Xiaoshuang Feng
Summary: Sensitivity to environmental concerns and the demand for metal-free polymeric materials have driven research towards breakthroughs in organocatalytic polymerizations. Triethyl borane (TEB) has been discovered as an exceptional Lewis acid, serving to generate ate complexes and activate epoxides. Lewis pairs consisting of alkyl boranes combined with onium salts or organic bases have demonstrated unprecedented versatility for (co)polymerizations of oxygenated monomers, producing various oxygenated polymers. This review summarizes the progress made in TEB-mediated polymerization systems and proposes future challenges in organocatalytic synthesis.
PROGRESS IN POLYMER SCIENCE
(2023)
Article
Polymer Science
Mingchen Jia, Jingjing Liu, Yves Gnanou, Xiaoshuang Feng
Summary: In this study, a series of ABA triblock copolymers were successfully synthesized using a one-pot method. The copolymers consisted of a poly(propylene carbonate-co-propylene oxide) middle block and two poly(N-tosyl propylene urethane) outer blocks. The synthesis was conducted using a difunctional initiator and triethyl borane (TEB). The copolymers exhibited well-defined structures as confirmed by 1H NMR and SEC. The thermal and mechanical properties of the copolymers were characterized using TGA, DSC, and UTM, showing higher toughness compared to commercial polyolefins.
Article
Polymer Science
Chao Chen, Yves Gnanou, Xiaoshuang Feng
Summary: This research describes the design and synthesis of organoboron catalysts for the alternating ring-opening copolymerization (ROCOP) of CO2 with cyclic ethers. The performance of these catalysts was assessed by considering various parameters, such as the type of boron center, the distance between the boron center and the ammonium cation, and the size of the substituents of the cation. Among all the boron-based catalysts, borinane-based catalyst 5 showed the highest productivity in the copolymerization of CO2 and epoxides. Additionally, catalyst 5 could be easily recycled and used as a difunctional initiator. Density Functional Theory computation provided insights into the mechanism of the bifunctional catalyst-mediated CO2 copolymerization and highlighted the importance of the type of boron centers in the overall performance.
Article
Polymer Science
Chao Chen, Yves Gnanou, Xiaoshuang Feng
Summary: This work presents an efficient method for utilizing carbon disulfide (CS2) as a sulfur-containing C1 resource to synthesize linear poly(trithiocarbonate)s and cyclic trithiocarbonates. The copolymerization of CS2 with episulfides, initiated by PPNCl or phosphazene benzoxide, leads to alternating poly(trithiocarbonate)s without any catalyst. In contrast, when initiated by tetrabutylammonium halide, the same reaction produces cyclic trithiocarbonates. The role of initiating onium salts in the linear/cyclic selectivity, as well as the impact of reaction conditions, such as temperature, solvent, and feeding ratio, were investigated. Additionally, poly(trithiocarbonate)s can be completely unzipped into cyclic trithiocarbonates when exposed to a radical source or UV irradiation. The potential of utilizing this feature to create degradable polymers using oligotrithiocarbonates as self-immolating linkers between dithiol alkyl precursors was explored.
