MACROMOLECULAR CHEMISTRY AND PHYSICS
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2021
·Vol. 223
·期 12
·2100321
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IF 2.527
Guanchen He,Heng Li,Junpeng Zhao
One-step synthesis of well-defined block copolymer is of great fundamental and practical values. Here, an aromatic-aliphatic block copolyester is one-step synthesized from the mixture of phthalic anhydride (PA), cyclohexene oxide (CHO), and δ -valerolactone ( δ -VL) at room temperature in the presence of a metal-free Lewis pair catalyst consisting of triethylborane and excess phosphazene base. Alcohol-initiated ring-opening alternating copolymerization of PA and CHO occurs first and selectively because of the overwhelmingly higher activity of PA than CHO and δ -VL toward the reaction with base-activated hydroxy species. Only after full conversion of PA is reached can ring-opening polymerization of δ -VL occur from the terminus of the aromatic polyester so that a well-defined (AB) n C m type block copolyester is formed. The two polymerizations are both highly chemoselective without homopolymerization of CHO or extensive transesterification reactions. Owing to the sequence-selective and living characteristics of the terpolymerization, hepta- and undecablock copolyesters with controlled molar mass and low dispersity are obtained through addition of the three-component monomer mixture in batches. Applicability of the method to propylene oxide and ε -caprolactone is also examined.
研究领域:
高分子化学
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材料科学
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DOI
高影响因子
Polymer Chemistry
·
2018
·Vol. 9
·期 45
·5470-5475
·
IF 4.927
Shanshan Chen,Liman Hou,Qiliao Wang,Dewen Dong,Ning Zhang
We demonstrate the first application of Lewis pair-mediated polymerization (LPP) in the efficient synthesis of cylindrical molecular brushes bearing poly(methyl methacrylate) and polylactone side chains. Poly(N-heterocyclic olefin) (poly(NHO)) as a macroinitiator precursor was firstly prepared by the reversible addition–fragmentation chain transfer (RAFT) polymerization of N-vinylimidazolium iodide and successive deprotonation in the presence of a strong base. Poly(NHO) together with Al(C6F5)3 can jointly promote the polymerization of methyl methacrylate and δ-valerolactone, leading to the formation of PMMA and polylactone side chains along the backbone via the grafting-from approach. NMR, GPC, AFM characterization and polymerization dynamic investigation indicate the successful formation of side chains and the resulting stretched conformation of the polymer backbone. DSC characterization reveals that molecular brushes have a higher glass transition temperature than their linear counterpart because of the branched architecture of molecular brushes. The current strategy represents a new avenue for the application of LPP and provides potential in the synthesis of polymers with well-defined topological structures.
研究领域:
高分子化学
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材料科学
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DOI
高影响因子
Polymer Chemistry
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2025
·
IF 3.9
Xianqiang Zeng,Chen Liu,Xue Wang,Yan Cao,Zheng Zheng,Peng He,Huiquan Li,Liguo Wang
Poly(1,2-butylene oxide) (PBO) with ethyl side chains exhibits enhanced hydrophobicity, lower glass transition temperatures, and more nonpolar characteristics compared to poly(propylene oxide) (PPO). However, the presence of large steric hindrance from side groups of 1,2-butylene oxide (BO) makes its ring-opening polymerization (ROP) inefficient. We report a metal-free Lewis pair catalytic system comprising triethylborane (Et3B) and tetrabutylphosphonium bromide (TBPBr) that overcomes these limitations. This catalyst enables quantitative BO conversion under mild conditions (−20 °C), delivering high molecular weight PBO with a narrow polydispersity index (Mn = 37.2 kg mol−1, Đ = 1.07) through controlled chain propagation. Notably, the exceptional active hydrogen tolerance of the system allows precise synthesis of low molecular weight PBO polyols (Mn = 1.4–3.5 kg mol−1, Đ ≤ 1.05) using diols as initiators, with MALDI-TOF analysis confirming hydroxyl end-group fidelity. Furthermore, PBO polyols can be used directly in the synthesis of polyurethanes without the need for refining. We examined the influence of interactions between Lewis acids and Lewis bases on polymerization, and the results indicate that moderate interaction is critical for achieving optimal polymerization activity. This research demonstrates that a rational combination of a two-component Lewis pair catalyst offers a straightforward and practical approach for synthesizing polyethers with long side chains.
研究领域:
有机化学
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高分子化学
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DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2025
·
IF 21.1
Hanfeng Ye,Min Zhou,Fanghua Zeng,Wandong Xing,Fei Zhao,Wing-Kei Ho,Yidong Hou,Can Yang
As significant supplements to metal-based catalysts, carbon-based catalysts have rarely been applied in selective catalytic oxidation of hydrogen sulfide (H 2 S-SCO) at 200–300 ℃ due to inevitable generation of abundant sulfur dioxide (SO 2 ). Due to the ability to activate and utilize SO 2 , the development of Lewis pairs (LPs) into carbon catalysts could be a feasible strategy to alleviate the above issue and realize desired performance but remains challenges. Herein, we propose an affinity-mildness strategy to prepare nitrogen and phosphorus codoped carbon (P-NDC) catalysts under mild conditions, and further reveal the key factors for universal synthesis of such advanced functional carbon materials. The electron-deficient P atom in the carbon matrix as Lewis acid and the electron-rich N atom of pyridinic N as Lewis base comprise LPs, which promote the chemisorption of SO 2 and H 2 S, respectively. Benefiting from this improvement, P-NDC strengthens the Claus reaction obeying Langmuir-Hinshelwood mechanism and exhibits a higher sulfur selectivity (96.1 %) than the carbon catalyst without LPs (78.8 %) during H 2 S-SCO process at 260 ℃, exceeding reported metal-based and metal-free-based catalysts. This work exemplifies the potential of functional carbon materials with LPs in waste-to-chemical fields, another step towards the optimization vision of carbon materials.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
EUROPEAN POLYMER JOURNAL
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2022
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IF 5.546
Lijun Wang,Fang Wang,Qiang Zhou,Yanfei Wang,Haixiang Song,Haiyang Yang
In recent years, the use of fluorescent amphiphilic polymers as the bioimaging agents has achieved significant progress, and promoted the development of the early stage cancer diagnosis and treatment. In this study, a serials of novel nitrobenzoxadiazole (NBD) fluorophore-functionalized polyester-based amphiphilic polymers were designed and synthesized via a two-step process: a hydrophobic polyester backbone was synthesized first by ring-opening alternating copolymerization (ROAC) of phthalic anhydride (PA) and allyl glycidyl ether (AGE) monomers using NBD-OH fluorophore as the initiator and metal-free Lewis pairs as the catalyst; then hydrophilic modified by three different hydrophilic pendants, PEG-SH, mercaptoacetic acid and mono-6-thio-β-cyclodextrin, through thiol-ene click reaction. Notably, directly using fluorophore as the initiator to initiate the ROAC of cyclic anhydrides and epoxides has never been reported. The influence of the feed ratio, type of Lewis pair and reaction temperature upon the polymerization performance were presented and the quantitative introduction of NBD and three kinds of hydrophilic pendants were described in detail as well. Due to the amphiphilic properties, these polymers could facilely self-assemble into fluorescent polymeric nanoparticles, which were characterized by a series of characterization techniques including surface tensiometer, dynamic light scattering (DLS), transmission electronic microscopy (TEM), and fluorescence spectroscopy. These fluorescent polymeric nanoparticles with diameters of tens or hundreds of nanometers showed good particle stability and good fluorescence performance in aqueous solution. The biocompatibility of these fluorescent polymeric nanoparticles was also excellent. In fact, the biological imaging of A549 cells could be realized successfully in the presence of the fluorescent polymeric nanoparticles. This work provides a new strategy and may inspire new approaches to the design and preparation of the biocompatible fluorescent amphiphilic polymers which could be used as the potential biological imaging agents in basic life science research and clinical applications.
研究领域:
材料科学
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生物医学工程
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高分子化学
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DOI
高影响因子
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