BoGeng Li

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Name: 李伯耿; BoGeng Li

Organization: Zhejiang University

Department: Department of Chemical & Biochemical Engineering, State Key Laboratory of Polymer Reaction Engineering

Title: Professor

TOPICS

Polymer

Block Copolymer Coordination Polymer

Chemicals
References

Engineering Elastic ZIF-8-Sponges for Oil–Water Separation

Co-reporter:He Zhu;Qi Zhang;Bo-Geng Li;Shiping Zhu

Advanced Materials Interfaces 2017 Volume 4(Issue 20) pp:

Publication Date(Web):2017/10/01

DOI:10.1002/admi.201700560

AbstractThis work reports a rapid and straightforward method to fabricate ZIF-8-melamine sponge composite with good mechanical properties, which overcomes the outstanding challenge of fabricating mechanically stable metal–organic framework (MOF)-based 3D structures. A continuous ZIF-8 thin layer is grown onto sponge skeleton by simple immersion of pristine sponge in ZIF-8 precursor solution. This method is rapid, cost-effective, easily scaled-up, and it does not require any premodification. The obtained ZIF-8 sponge shows an excellent compressive behavior and ZIF-8 thin layer remained intact after over ten cycles of compression tests. In addition, the MOF/polymer shows an outstanding absorption performance of organic solvents, good recoverability, and good recyclability, demonstrating its potential in cleaning up oil spills.

Cleavable polybutadiene rubber: A versatile precursor to hydroxyl-terminated or multi-hydroxyl polybutadiene and polyethylene

Co-reporter:Qinzhuo Zhou, Anqi Wang, Lu Dai, Suyun Jie, Bo-Geng Li

Polymer 2016 Volume 107() pp:306-315

Publication Date(Web):19 December 2016

DOI:10.1016/j.polymer.2016.11.033

•MHPB with α,ω- and controllable intrachain hydroxyl groups was synthesized.•Hydroxyl functionalized polyethylenes (HTPE, FHTPE and MHPE) were synthesized.•Linear HTPE has high degree of crystallinity (70%) and melting temperature (123.2 °C).•MHPE has lower degree of crystallinity (47%) and melting temperature (110.9 °C).A series of hydroxyl functionalized polybutadienes has been prepared by combining the oxidolysis and reduction of cis-polybutadiene rubber (BR). For the first time, multi-hydroxyl polybutadiene (MHPB) with α,ω- and intrachain hydroxyl groups was synthesized through the simultaneous reduction of –CHO and epoxy groups in epoxidized aldehyde group terminated polybutadiene (EATPB) by sodium dihydro-bis-(2-methoxyethoxy) aluminate (Red-Al). The corresponding hydroxyl functionalized polyethylenes, including hydroxyl-terminated polyethylene (HTPE), multi-hydroxyl polyethylene (MHPE) and hydroxyl-terminated polyethylene with ethyl branches (FHTPE), were readily obtained via the hydrogenation of C=C double bonds in the functionalized polybutadienes with TSH/TPA regents. The microstructures of all the products were confirmed by 1H NMR, 13C NMR and FT-IR, and their thermal properties were determined by TGA and DSC. It has been indicated that the linear HTPE and MHPE possessed high initial thermal degradation temperature, high degree of crystallinity, and high melting temperature due to their stereoregular microstructure. However, the FHTPE obtained through the hydrogenation of HTPB from free radical polymerization had much lower degree of crystallinity and melting temperature due to the presence of more ethyl branches.

Synthesis of Ultrahigh-Molecular-Weight Ethylene-1-Hexene Copolymers with High Hexene Content via Living Polymerization with Fluorinated Bis(phenoxyimine) Titanium(IV)

Co-reporter:Song Guo;Hong Fan;Zhiyang Bu;Bo-Geng Li;Shiping Zhu

Macromolecular Rapid Communications 2015 Volume 36( Issue 3) pp:286-291

Publication Date(Web):

DOI:10.1002/marc.201400564

Progress of Polymer Reaction Engineering Research in China

Co-reporter:Bo-Geng Li;Wen-Jun Wang

Macromolecular Reaction Engineering 2015 Volume 9( Issue 5) pp:385-395

Publication Date(Web):

DOI:10.1002/mren.201500051

The polymer industry in China has developed rapidly over the past 30 years, which can be greatly attributed to the active R&D conducted by Chinese scholars in polymer reaction engineering (PRE) and their cultivation of high level talents. The research focus on PRE in China has shifted from the application development to both applied and fundamental research at present. The PRE researchers closely collaborate with the enterprises and the world leading scholars. The research objective has been evolved from optimizing efficiency of polymerization processes to precise control of the structures of polymer chains and primary aggregates. This essay summarizes the history, characteristics, and latest progresses of the PRE research in China, with emphasis on the research activities at Zhejiang University.

High Temperature High Pressure Tandem Polymerization of Ethylene for Synthesis of Ethylene-1-Hexene Copolymers from Single Reactor with SNS-Cr and CGC-Ti Catalysts

Co-reporter:Song Guo;Hong Fan;Zhiyang Bu;Bo-Geng Li;Shiping Zhu

Macromolecular Reaction Engineering 2015 Volume 9( Issue 1) pp:32-39

Publication Date(Web):

DOI:10.1002/mren.201400027

Ethylene-1-hexene copolymers are synthesized from ethylene using the tandem catalyst system of bis(2-dodecylsulfanyl-ethyl)amine-CrCl₃ (SNS-Cr) and [(η⁵-C₅Me₄)SiMe₂(^tBuN)]TiCl₂ (CGC-Ti), with MAO as co-catalyst. The tandem polymerization is carried out in a high-temperature high-pressure solution process. SNS-Cr trimerizes ethylene and generates 1-hexene with high selectivity. CGC-Ti copolymerizes ethylene with 1-hexene and produces the ethylene-1-hexene copolymers. A short period of pre-trimerization is effective in increasing the 1-hexene content in copolymer and producing chains with uniform microstructure. The products prepared by this tandem system at high temperature and high pressure exhibit competitive mechanical properties with a commercial ethylene-1-octene copolymer.

Elastomeric properties of ethylene/1-octene random and block copolymers synthesized from living coordination polymerization

Co-reporter:Weifeng Liu, Xiao Zhang, Zhiyang Bu, Wen-Jun Wang, Hong Fan, Bo-Geng Li, Shiping Zhu

Polymer 2015 Volume 72() pp:118-124

Publication Date(Web):18 August 2015

DOI:10.1016/j.polymer.2015.07.019

•LRC had better elasticity than MRC.•The strain recovery of LRC kept 90% with an applied strain up to 800%.•LBC1 retained the strain recovery about 80% under the applied stain of 600%.•The elasticity of block copolymers was mainly determined by their block structure.The elastomeric performance of a series of ethylene/1-octene random and block copolymers prepared from living coordination polymerization was studied in this work. All the polymer samples exhibited good toughness. The living random copolymers had better elasticity than commercial metallocene random copolymers. The strain recovery of the living random copolymers was about 90% with an applied strain up to 800%. It was demonstrated that the copolymer elasticity was mainly determined by their block structure, with little influence by their molecular weight. It was also found that either too high or too low content of hard-block content deteriorated the copolymer elastomeric behavior. The diblock copolymer having about 42 wt% hard block content (LBC1) gave the best elasticity among the studied block copolymers and retained the strain recovery about 80% under the applied stain of 600%.

Structure analysis of ethylene/1-octene copolymers synthesized from living coordination polymerization

Co-reporter:Weifeng Liu, Wen-Jun Wang, Hong Fan, Luqiang Yu, Bo-Geng Li, Shiping Zhu

European Polymer Journal 2014 Volume 54() pp:160-171

Publication Date(Web):May 2014

DOI:10.1016/j.eurpolymj.2014.03.010

•The chain microstructures of living copolymers were studied by TREF and SSA.•LRC possessed narrower intrachain composition distribution than MRC.•The interchain composition distribution of LBC was narrower than OBC.•The crystal thickness distribution of OBC was narrower than LBC.A series of ethylene/1-octene random and block copolymer samples were synthesized via a living coordination polymerization catalyzed by bis[N-(3-methylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] titanium(IV) dichloride/dMAO. The chain microstructures of the copolymers were elucidated by analytic TREF and DSC thermal fractionation techniques in this work. It was found that the living random copolymers possessed narrower intrachain composition distributions than those prepared from conventional metallocene catalysts. With the same short chain branching content, the melting temperature of living random copolymer was about 16 °C lower than metallocene-catalyzed random copolymer. The living block copolymers were also studied in comparison with the olefin multiblock copolymer (OBC) produced from chain shuttling polymerization. The interchain composition distribution of OBC was found broader than living block copolymers. However, the crystal thickness distribution of OBC was narrower. The diblock copolymer had a bimodal distribution in the crystal thickness and the step triblock copolymer showed a trimodal distribution, in contrast to OBC’s single modal distribution.Graphical abstract

Tandem Action of SNSCr and CGCTi in Preparation of Ethylene1-Hexene Copolymers from Ethylene Feedstock

Co-reporter:Song Guo;Hong Fan;Zhiyang Bu;Bo-Geng Li;Shiping Zhu

Macromolecular Chemistry and Physics 2014 Volume 215( Issue 17) pp:1661-1667

Publication Date(Web):

DOI:10.1002/macp.201400290

Monochromatic light-emitting copolymer of methyl methacrylate and Eu-complexed 5-acrylamido-1,10-phenanthroline

Co-reporter:Cun-Jin Xu, Jin-Tao Wan, Bo-Geng Li

Dyes and Pigments 2013 Volume 98(Issue 3) pp:493-498

Publication Date(Web):September 2013

DOI:10.1016/j.dyepig.2013.04.001

•A luminescent copolymer of MMA and Eu-complexed 5-acrylamido-1,10-phenanthroline.•Photophysical properties of the copolymer were studied.•The Judd–Ofelt theory was used to analyze the luminescence spectra of the copolymer.•The copolymer may be a promising candidate for a pure red-emitting polymer material.We present an effective approach to prepare Eu-containing polymer with excellent photoluminescence properties through the copolymerization of highly luminescent Eu-complex monomer featuring 2-thenoyltrifluoroacetone (HTTA) and 5-acrylamido-1,10-phenanthroline with methyl methacrylate (MMA). The copolymer was characterized by FT-IR, UV–Vis, 1H NMR, GPC, TGA, and DSC. The results reveal that the copolymer is readily soluble, and possesses excellent thermal stability, with high glass transition and decomposition temperatures of 125 and 335 °C, respectively. Intense red emission peaked at 612 nm, corresponding to the 5D0 → 7F2 transition of Eu(III) ions is recorded under UV excitation. The luminescence lifetimes and efficiencies of some Eu-containing monomers could be greatly enhanced upon copolymerization. The special microenvironment, in which the Eu-complex units are uniformly bonded to and surrounded by the polymer chain, appears to be responsible for the improvement of the luminescence properties for the copolymer. Moreover, the applicability of the well-known Judd–Ofelt theory to the luminescence properties of Eu3+ complexes is also investigated.

Synthesis of molecular weight controllable bimodal polyethylene from fluorinated FI–Ti catalyst coupled with ZnEt2

Co-reporter:Weifeng Liu, Song Guo, Zhiyang Bu, Hong Fan, Wen-Jun Wang, Bo-Geng Li

European Polymer Journal 2013 Volume 49(Issue 7) pp:1823-1831

Publication Date(Web):July 2013

DOI:10.1016/j.eurpolymj.2013.04.008

•Molecular weight controllable bimodal polyethylene was synthesized using a fluorinated FI–Ti catalyst and ZnEt2.•ZnEt2 was a useful molecular weight regulator.•The high molecular weight fraction could be controlled via altering the living polymerization time.•The low fraction could be controlled via varying the Zn/Ti ratio.Molecular weight controllable bimodal polyethylene was synthesized by adding ZnEt2 during ethylene living polymerization with the fluorinated FI–Ti catalyst system, bis[N-(3-methylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] TiCl2/dMAO. The presented FI–Ti catalyst system was demonstrated to perform good living feature. High molecular weight polyethylene with narrow polydispersity was obtained in the absence of ZnEt2. ZnEt2 was found to be a useful molecular weight regulator in this catalyst system. Increasing the Zn/Ti ratio led to a monotonic decrease in the molecular weight. The stagewise process allowed for a facile control on the molecular weight of bimodal polyethylene in a wide range: the molecular weight of high fraction could be controlled via altering the living polymerization time, the molecular weight of low fraction could be controlled via varying the Zn/Ti ratio. This method shows a new application for the living coordination polymerization technique.

Potential for Using Simple 1,2,4-Triazole Salt Solutions as Highly Efficient CO2 Absorbents with Low Reaction Enthalpies

Co-reporter:Jie Ren, Linbo Wu, and Bo-Geng Li

Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 25) pp:8565

Publication Date(Web):June 4, 2013

DOI:10.1021/ie4006386

Simple solutions of alkali metal salts of 1,2,4-triazole (TrizM) in polyethyelene glycol (PEG) and dimethylsulfoxide (DMSO) were prepared and assessed for CO2 capture. These aprotic heterocyclic anions (AHAs) containing solutions exhibit excellent CO2 capture performances. The TrizM salts absorb CO2 chemically in a 1:1 stoichiometry. What is more attractive is that the CO2 chemical absorption enthalpies are as low as −33 ∼ −21 kJ mol–1, close to that of physical absorption by traditional ionic liquids (ILs). This makes regeneration of the absorbents highly energy-saving. The TrizM-PEG solution has a steady CO2 capture performance due to the nonvolatility of PEG, and therefore, it is durable for CO2 capture. In comparison, the TrizM-DMSO solution has a higher absorption capacity (120 mg/g solution) because of the higher solubility of TrizM. Such simple and inexpensive solutions show new potential as promising candidates for highly efficient, energy-saving, and economical CO2 catchers.

Living copolymerization of ethylene/1-octene with fluorinated FI-Ti catalyst

Co-reporter:Weifeng Liu;Kailun Zhang;Hong Fan;Wen-Jun Wang;Bo-Geng Li;Shiping Zhu

Journal of Polymer Science Part A: Polymer Chemistry 2013 Volume 51( Issue 2) pp:405-414

Publication Date(Web):

DOI:10.1002/pola.26398

Abstract

Living copolymerization of ethylene and 1-octene was carried out at room temperature using the fluorinated FI-Ti catalyst system, bis[N-(3-methylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] TiCl₂/dried methylaluminoxane, with various 1-octene concentrations. The comonomer incorporation up to 32.7 mol % was achieved at the 1-octene feeding ratio of 0.953. The living feature still retained at such a high comonomer level. The copolymer composition drifting was minor in this living copolymerization system despite of a batch process. It was found that the polymerization heterogeneity had a severe effect on the copolymerization kinetics, with the apparent reactivity ratios in slurry significantly different from those in solution. The reactivity ratios were nearly independent of polymerization temperature in the range of 0–35 °C. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Polymerization of 1,3-butadiene catalyzed by cobalt(II) and nickel(II) complexes bearing imino- or amino-pyridyl alcohol ligands in combination with ethylaluminum sesquichloride

Co-reporter:Pengfei Ai, Lin Chen, Yintian Guo, Suyun Jie, Bo-Geng Li

Journal of Organometallic Chemistry 2012 705() pp: 51-58

Publication Date(Web):

DOI:10.1016/j.jorganchem.2012.01.013

Stereospecific polymerization of 1,3-butadiene catalyzed by cobalt complexes bearing N-containing diphosphine PNP ligands

Co-reporter:Lin Chen, Pengfei Ai, Jianming Gu, Suyun Jie, Bo-Geng Li

Journal of Organometallic Chemistry 2012 716() pp: 55-61

Publication Date(Web):

DOI:10.1016/j.jorganchem.2012.05.051

Design, synthesis and characterization of a highly luminescent Eu-complex monomer featuring thenoyltrifluoroacetone and 5-acryloxyethoxymethyl-8-hydroxyquinoline

Co-reporter:Cun-Jin Xu, Bo-Geng Li, Jin-Tao Wan, Zhi-Yang Bu

Journal of Luminescence 2011 Volume 131(Issue 8) pp:1566-1570

Publication Date(Web):August 2011

DOI:10.1016/j.jlumin.2011.03.047

A multi-functional ligand, 5-acryloxyethoxymethyl-8-hydroxyquinoline (Hamq), was synthesized, which contained a polymerizable C=C double bond for the copolymerization with other vinyl monomers and acted as photon antenna able to transfer energy to Eu3+ ions effectively. The triplet state energy of Hamq was determined to be 22,370 cm−1 via the phosphorescence spectra of Hamq and its gadolinium complex. The title complex monomer Eu(tta)2(amq) was prepared by coordination reaction of Hamq with europium isopropoxide and 2-thenoyltrifluoroacetone (Htta) in dry organic solvents under argon atmosphere and characterized by elemental analysis and IR spectrum. The photophysical properties of the complex were studied in detail with UV–vis, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (30.6%) upon ligand excitation and a long 5D0 lifetime (389 μs), which indicated that the ligand Hamq could sensitize the luminescence of Eu(III) ion efficiently in Eu(tta)2(amq), resulting in a strong luminescence of its copolymer poly[MMA-co-Eu(TTA)2(amq)] under UV excitation. The excellent luminescence properties of the complex made it not only a promising light-conversion molecular device but also an excellent luminescent monomer.Highlights►iWe designed and synthesized a highly luminescent Eu-complex monomer. ► Quantum yield and lifetime of the complex are 30.6% and 389 μs, respectively. ► Excellent luminescence of the complex made it an excellent luminescent monomer.

Model-fitting and model-free nonisothermal curing kinetics of epoxy resin with a low-volatile five-armed starlike aliphatic polyamine

Co-reporter:Jintao Wan, Zhi-Yang Bu, Cun-Jin Xu, Hong Fan, Bo-Geng Li

Thermochimica Acta 2011 Volume 525(1–2) pp:31-39

Publication Date(Web):20 October 2011

DOI:10.1016/j.tca.2011.07.018

This paper reports the original work on the nonisothermal curing reaction of bisphenol A epoxy resin (DGEBA) and N,N,N′,N′,N′′-penta(3-aminopropyl)-diethylenetriamine (PADT). The nonisothermal reaction kinetics of DGEBA/PADT is systematically investigated using dynamic DSC with the model-fitting and advanced model-free isoconversional methods. The high reaction heats (115–118 kJ/mol) indicate that PADT can efficiently cure DGEBA, and the reaction activation energy is 55.4 kJ/mol. The further reaction kinetic analysis with the Málek method discloses the autocatalytic characteristic, and the Šesták–Berggren model is able to well simulate the reaction rate. Furthermore, the dependence of the effective activation energy on conversion is established from the model-free kinetic analysis with the Vyazovkin method, from which the reaction mechanisms are discussed in detail. Additionally, the isothermal conversion predication from the nonisothermal data is accomplished using the two methods, respectively, with an acceptable match obtained.Graphical abstractHighlights► Nonisothermal cure reaction of DGEBA/PADT is examined with DSC. ► Model-fitting and advanced model-free isoconversional methods are used to the curing kinetic analysis. ► Reaction rate equation is established with the Málek method. ► Effective activation energy determined from the Vyazovkin method is interpreted in detail. ► Isothermal conversion prediction from the nonisothermal data is accomplished.

Preparation, melting, glass relaxation and nonisothermal crystallization kinetics of a novel dendritic nylon-11

Co-reporter:Jintao Wan, Zhi-Yang Bu, Cheng Li, Hong Fan, Bo-Geng Li

Thermochimica Acta 2011 Volume 524(1–2) pp:117-127

Publication Date(Web):20 September 2011

DOI:10.1016/j.tca.2011.07.002

A novel dendritic nylon-11, DPA-11, is prepared from the melting copolycondensation of 11-aminoundecanoic acid and the 2nd generation poly(propyleneimine) dendrimer as the dendritic unit, with its melting, glass-transition and nonisothermal crystallization behaviors highlighted. DPA-11 is characterized using FTIR, TGA, WXRD and DSC. The results show that PDA-11 has excellent thermal stability, at room temperature its δ′-form crystal is predominant, and the dual melting processes and glass transition occur during the heating. The subsequent crystallization kinetic analysis with JMA, Ozawa and Mo methods demonstrates the mechanisms and crystallizability changing with the relative crystallinity, α, especially, during the primary and secondary crystallization stages. Moreover, applying the Vyazovkin method yields the dependence of the effective activation energy on crystallinity, from which the crystallization mechanisms are discussed in detail. Then the equilibrium melting temperature is determined, being 200.9 °C. Furthermore, the spherulitic growth analysis with the extended Hoffman–Lauritzen method produces the Regime I/II transition temperature of 158° C.Graphical abstractHighlights► A novel dendritic nylon-11 (DPA-11) is prepared and characterized using FTIR, TGA, WXRD, and DSC. ► The melting, glass relaxation and nonisothermal crystallization kinetics of DPA-11 is systematically studied by comparing with linear nylon-11. ►The isothermal crystallization kinetics of DPA-11 is analyzed using a number of classic methods (JMA, Ozawa, Mo and Vyazovkin). ► The equilibrium melting point of DPA-11 is determined from the Hoffman–Weeks method. ►The spherulitic growth of DPA-11 is examined using the extended Hoffman-Lauritzen method.

Learning about novel amine-adduct curing agents for epoxy resins: Butyl-glycidylether-modified poly(propyleneimine) dendrimers

Co-reporter:Jintao Wan, Zhi-Yang Bu, Cun-Jin Xu, Bo-Geng Li, Hong Fan

Thermochimica Acta 2011 Volume 519(1–2) pp:72-82

Publication Date(Web):20 May 2011

DOI:10.1016/j.tca.2011.02.038

Novel butyl-glycidylether-modified poly(propyleneimine) dendrimers (PPIs) are prepared by reacting butyl glycidylether with PPI, which turn out to be able to cure bisphenol-A epoxy resin to an acceptable reaction extent. The nonisothermal reactions, dynamic mechanical properties and thermal stabilities of their cured epoxy resin are comparatively investigated with DSC, DMA and TGA, respectively. The model-fitting kinetic study demonstrates that Šesták–Berggren model can generally well simulate the reaction rates, and the isoconversional kinetic analysis with the Vyazovkin method indicates the curing agents, particularly their setric hindrance and the number of the –OH groups attached, greatly affect reaction kinetic schemes. Increasing the number of the BGE substituents attached to PPIs decreases the reactivity, glass- and beta-relaxation temperatures and thermal stability of the resulting epoxy systems, yet the intensity and width of the glass relaxation increase. This work offers a unique way of preparing modified-aliphatic-polyamine curing agents, and provides an opportunity to better learn about the amine-adduct curing agents which are widely used in room-temperature-cure epoxy coatings and adhesives from these good model compounds.Graphical abstractHighlights► Butyl-glycidylether-modified poly(propylene imine) dendrimers are successfully prepared. ► They, as novel hardeners, have high reactivity and can well cure epoxy resin nonisothermally. ► The Šesták–Berggren model can generally well simulate the epoxy reaction rates. ► The model-free isoconversional kinetic analysis are performed with the Vyazovkin method. ► Influences of the hardeners on curing behaviors and thermal properties of the epoxy are revealed.

Synthesis and characterization of a Eu-containing polymer precursor featuring thenoyltrifluoroacetone and 5-acrylamido-1,10-phenanthroline

Co-reporter:Cun-Jin Xu, Bo-Geng Li, Jin-Tao Wan, Zhi-Yang Bu

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2011 Volume 82(Issue 1) pp:159-163

Publication Date(Web):November 2011

DOI:10.1016/j.saa.2011.07.027

A polymerizable ligand, 5-acrylamido-1,10-phenanthroline (L), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR, MS, and 1H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex shows a remarkable luminescence quantum yield at room temperature (40.1%) upon ligand excitation and a long 5D0 lifetime (590 μs), which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor.Graphical abstractHighlights► We designed and synthesized a highly luminescent Eu-containing polymer precursor. ► The precursor shows a remarkable quantum yield (40.1%) and a long lifetime (590 μs). ► The excellent luminescence of the precursor made it an excellent luminescent monomer.

Nonisothermal reaction, thermal stability and dynamic mechanical properties of epoxy system with novel nonlinear multifunctional polyamine hardener

Co-reporter:Jintao Wan, Bo-Geng Li, Hong Fan, Zhi-Yang Bu, Cun-Jin Xu

Thermochimica Acta 2010 Volume 511(1–2) pp:51-58

Publication Date(Web):20 November 2010

DOI:10.1016/j.tca.2010.07.024

N,N,N′,N′-tetra(3-aminopropyl)-1,6-diaminohexane (TADH), a nonlinear multifunctional polyamine, was prepared and employed as a novel hardener for diglycidyl ether of bisphenol A (DGEBA). Nonisothermal reactions of DGEBA/TADH were systematically investigated with differential scanning calorimetry (DSC). According to the Málek method, the two-parameter Šesták–Berggren model was selected to simulate the reaction rate with a good match achieved, and a correlation of effective activation energies Eα with fractional conversion α was determined with the mode-free isoconversional Vyazovkin method. As α rose, Eα reduced quickly from ∼65 to 57 kJ/mol up to α ≈ 15%, then decreased slowly to ∼50 kJ/mol till α ≈ 75%, and finally dropped to ∼30 kJ/mol at full conversion. In addition, analysis of thermal stability of the cured DGEBA/TADH with thermogravimetric analysis (TGA) revealed that it possessed quite good thermal stability and increased residual char content at 600 °C in nitrogen. Furthermore, dynamic mechanical analysis (DMA) of the DGEBA/TADH network showed its relaxations were characterized by localized motions of hydroxyl ether segments (β relaxation) and cooperative motions of whole network chains (glass relaxation) at different temperature regions.

The effect of ligand molecular weight on copper salt catalyzed oxidative coupling polymerization of 2,6-dimethylphenol

Co-reporter:Ying Zhao;Linbo Wu;Bo-Geng Li;Shiping Zhu

Journal of Applied Polymer Science 2010 Volume 117( Issue 6) pp:3473-3481

Publication Date(Web):

DOI:10.1002/app.32252

Abstract

Polyphenylene oxide (PPO) was prepared via oxidative coupling polymerization of 2,6-dimethylphenol (DMP) catalyzed by copper salt. The ligand was a novel series of random copolymers (PSVP) of styrene and 4-vinylpyridine prepared by reversible addition-fragmentation chain transfer (RAFT) copolymerization. The copolymers with well-controlled molecular weight (MW) were used to study the effects of ligand molecular weight on the catalytic activity and selectivity. It was found that the catalytic activity increased with the molecular weight but there existed an upper MW limit above which no further increase in activity could be achieved. With PSVP of F_vPy = 0.39, the critical MW was about 5000 g/mol. The mechanism involved in the successive complexation of copper ions and PSVP was elucidated and the equilibrium constants were estimated by pH titration. It was found that the macromolecular ligand was in favor of bridging Cu^II ions that formed catalytically active dinuclear copper-amine complexes. However, the catalytic selectivity was almost independent of the ligand MW. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesis and Characterization of Highly Luminescent Copolymers of Methyl Methacrylate and Eu-Complexed 5-Acryloxyethoxymethyl-8-hydroxyquinoline

Co-reporter:Cun-Jin Xu;Bo-Geng Li

Macromolecular Chemistry and Physics 2010 Volume 211( Issue 16) pp:1733-1740

Publication Date(Web):

DOI:10.1002/macp.201000026

Preparation and SO2 Sorption/Desorption Behavior of an Ionic Liquid Supported on Porous Silica Particles

Co-reporter:Zhengmin Zhang, Linbo Wu, Jie Dong, Bo-Geng Li and Shiping Zhu

Industrial & Engineering Chemistry Research 2009 Volume 48(Issue 4) pp:2142-2148

Publication Date(Web):January 15, 2009

DOI:10.1021/ie801165u

The ionic liquid 1,1,3,3-tetramethylguanidinium lactate (TMGL) was supported onto porous silica particles via a facile impregnation−vaporization method. The TMGL-supported particles gave high porosity and large specific surface area. The SO2 sorption/desorption properties of the silica-supported TMGL (TMGL−SiO2) were evaluated, and high SO2 sorption capacity and rate were achieved. Its capacity reached 0.6 g SO2/g TMGL in 15−30 min with pure SO2 gas and 0.15 g SO2/g TMGL in 17 h with a N2/SO2 mixture gas that contained 2160 ppm SO2. The SO2 concentration was reduced to 12.6 ppm after sorption. The TMGL−SiO2 system could be reused for many sorption/desorption cycles without change in its capacity. It was also characterized by good mechanical strength and thermal stability at temperature up to 130 °C. The SO2 sorbent system appears to be useful in gas desulfurization.

Thermal stability of aromatic polyesters prepared from diphenolic acid and its esters

Co-reporter:Zhang Ping, Wu Linbo, Li Bo-Geng

Polymer Degradation and Stability 2009 Volume 94(Issue 8) pp:1261-1266

Publication Date(Web):August 2009

DOI:10.1016/j.polymdegradstab.2009.04.015

The thermal performance of aromatic polyesters (poly(DPA–IPC), poly(MDP–IPC) and poly(EDP–IPC)) prepared from isophthaloyl chloride (IPC) with diphenolic acid (DPA) and its esters were studied with DSC and TG, and the decomposition mechanism of poly(DPA–IPC) were investigated using FTIR and integrated TG/FTIR analyses. As compared with ordinary aromatic polyesters, poly(DPA–IPC) has lower glass transition temperature (159 °C) and much lower thermal stability. It starts to decompose at about 210 °C and is characterized by two-stage thermal decomposition behavior, with active energies of decomposition of 206 kJ/mol and 389 kJ/mol, respectively. The analyses of the decomposition process and products indicate that the pendent carboxyl groups in poly(DPA–IPC) are responsible for its low thermal stability. Accordingly, a decomposition mechanism for the first stage is proposed. With this knowledge in mind, we capped the carboxyl groups in DPA with methyl and ethyl groups to prepare poly(MDP–IPC) and poly(EDP–IPC) from methyl diphenolate and ethyl dipenolate. As expected, these two polymers exhibit obviously improved thermal stability, with onset decomposition temperature of about 300 °C.

Effect of monomer composition on apparent chain transfer coefficient in reversible addition fragmentation transfer (RAFT) copolymerization

Co-reporter:Jing Gao, Yingwu Luo, Rui Wang, Xiaojuan Zhang, Bo-Geng Li, Shiping Zhu

Polymer 2009 50(3) pp: 802-809

Publication Date(Web):

DOI:10.1016/j.polymer.2008.12.014

Phase Behavior of Ternary Homopolymer/Gradient Copolymer Blends

Co-reporter:Rui Wang, Weihua Li, Yingwu Luo, Bo-Geng Li, An-Chang Shi and Shiping Zhu

Macromolecules 2009 Volume 42(Issue 6) pp:2275-2285

Publication Date(Web):February 25, 2009

DOI:10.1021/ma801398a

The phase behavior of ternary homopolymer/gradient copolymer blends is studied theoretically using a multiblock model of gradient copolymers. Critical lines and Lifshitz points of the blends are determined by a random phase approximation analysis. Phase diagrams and microphase structures of the blends are studied using self-consistent mean-field theory. It is discovered that the chain gradient distribution has a significant effect on the phase behavior of the blends. When the chain gradient distribution is gradual, a larger amount of copolymers and a higher incompatibility are needed for the formation of a microphase. In addition, the ability of copolymer domains to absorb homopolymers decreases, whereas the solubility of copolymers in homopolymer matrix increases, as the gradient distribution becomes gradual. Another important effect is that gradient copolymers lead to a broad interface between two incompatible polymers. These results indicate that interfacial structure and morphology of these blends can be fine-tuned by specifically designed gradient distributions.

Modeling of Branching and Gelation in RAFT Copolymerization of Vinyl/Divinyl Systems

Co-reporter:Rui Wang, Yingwu Luo, Bo-Geng Li and Shiping Zhu

Macromolecules 2009 Volume 42(Issue 1) pp:85-94

Publication Date(Web):December 3, 2008

DOI:10.1021/ma802006c

The reversible addition−fragmentation chain transfer radical polymerization (RAFT) with branching/cross-linking is theoretically investigated on the basis of the method of moments. The system considered consists of the copolymerization of vinyl monomer in the presence of a small amount of divinyl comonomer. It is found that the gel point is significantly postponed by increasing the RAFT agent concentration. Flory’s criterion, ρrw,0 = 1, is found to be satisfied at the gel point in the RAFT cross-linking process regardless of the unequal reactivities of vinyl/divinyl monomers in the absence of cyclization. The gel conversion can be analytically expressed and is determined by the polymerization recipe and the relative reactivities of various double bonds. The gel point is postponed by the presence of intramolecular cyclization, and its effect becomes significant in a dilute polymerization system. Branching distribution is found to be very broad with a large fraction of linear primary and slightly branched chains. By the introduction of the dependence of the reactivity of the pendant double bond on the local heterogeneity, the branching distribution becomes narrower and can be fine-tuned.

Influence of clay and predispersion method on the structure and properties of polystyrene (PS)-clay nanocomposites

Co-reporter:Jintao Yang;Hong Fan;Zhiyang Bu;Bo-Geng Li

Polymer Engineering & Science 2009 Volume 49( Issue 10) pp:1937-1944

Publication Date(Web):

DOI:10.1002/pen.21425

Abstract

To prepare the polystyrene (PS)-clay nanocomposites via an in situ emulsion polymerization, a clay predispersion method, i.e. dispersing the organic clay in the emulsifier solution by the assistance of ultrasonic, was proposed in this study. The conventional method, predispersing the organic clay into the monomer, was also presented for the comparison. The morphology analysis based on the X-ray Deflection (XRD) and Transmission Electronic Microscopy (TEM) results suggested that the more uniform clay dispersion in the final nanocomposites could be achieved through the new method. The inorganic clay (Na-MMT) and two organic clays (C₁₈-MMT and VC₁₈-MMT) synthesized by exchanging inorganic cations with the trimethyloctadecyl ammonium chloride (OTAC) and the vinylbenzyldimethyloctadecyl ammoniun chloride (VOAC) were chosen to investigate the influence of the clay surface modification on the properties of nanocomposites. The Dynamic Mechanical Analysis (DMA) results showed the storage modulus G′s of the nanocomposites had different enhancements over that of the pure PS, especially when the temperature approached the glass transition temperature (T_g). The T_gs of the nanocomposites, however, varied with the microstructure and the interactions between the polymer and the clay layers. The Na-MMT and VC₁₈-MMT increased the T_g, while the T_gs of PS/C₁₈-MMT nanocomposites were slightly lower than that of the pure PS. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Effect of Catalysts Supporting on Tandem Polymerization of Ethylene Stock in Synthesis of Ethylene−1-Hexene Copolymer

Co-reporter:Junwei Zhang, Hong Fan, Bo-Geng Li and Shiping Zhu

Industrial & Engineering Chemistry Research 2008 Volume 47(Issue 15) pp:5369

Publication Date(Web):June 25, 2008

DOI:10.1021/ie7017564

Ethylene−1-hexene copolymers were synthesized with a tandem catalysis system consisting of a new trimerization catalyst (1), bis(2-dodecylsulfanylethyl)amine−CrCl3, and a copolymerization catalyst (2), Et(Ind)2ZrCl2. Catalysts 1 and 2 were supported on silica particles, and the effects of different supporting strategies on trimerization selectivity, 1-hexene incorporation efficiency, and copolymerization activity were studied and compared to the homogeneous system. It was found that the supported 1 trimerized ethylene with a similar selectivity (>99%) but one-quarter of the activity of the homogeneous 1. The supported 2 gave 40% 1-hexene incorporation efficiency and one-third of the copolymerization activity of the homogeneous 2. The tandem action of the supported 1 and 2 yielded linear low-density polyethylene (LLDPE) materials that contained only C4 side-chains. The dual supported system had activities at a 107 g/(mol Zr h) level, in the same order of the homogeneous counterpart. Adjusting the Cr/Zr ratio yielded various branching densities and, thus, melting temperatures of the resulting polymers. The samples prepared with the supported 2 exhibited broad differential scanning calorimetry (DSC) curves, probably due to multiple active sites.

Macromol. React. Eng. 4/2008

Co-reporter:Xiaoxiang Zhu;Bo-Geng Li;Linbo Wu;Yougui Zheng;Shiping Zhu;Klaus-Dieter Hungenberg;Stefan Müssig;Birgit Reinhard

Macromolecular Reaction Engineering 2008 Volume 2( Issue 4) pp:

Publication Date(Web):

DOI:10.1002/mren.200890006

Macromol. React. Eng. 4/2008

Co-reporter:Xiaoxiang Zhu;Bo-Geng Li;Linbo Wu;Yougui Zheng;Shiping Zhu;Klaus-Dieter Hungenberg;Stefan Müssig;Birgit Reinhard

Macromolecular Reaction Engineering 2008 Volume 2( Issue 4) pp:

Publication Date(Web):

DOI:10.1002/mren.201190014

Kinetics and Modeling of Vinyl Acetate Graft Polymerization from Poly(ethylene glycol)

Co-reporter:Xiaoxiang Zhu;Bo-Geng Li;Linbo Wu;Yougui Zheng;Shiping Zhu;Klaus-Dieter Hungenberg;Stefan Müssig;Birgit Reinhard

Macromolecular Reaction Engineering 2008 Volume 2( Issue 4) pp:321-333

Publication Date(Web):

DOI:10.1002/mren.200800011

Biodegradable Polymers from 5-Hydroxylevulinic Acid: 1. Synthesis and Characterization of Poly(5-hydroxylevulinic acid)

Co-reporter:Linbo Wu;Yan Zhang;Hong Fan;Zhiyang Bu

Journal of Polymers and the Environment 2008 Volume 16( Issue 1) pp:68-73

Publication Date(Web):2008 January

DOI:10.1007/s10924-008-0082-y

As an attempt to synthesize new biodegradable polymers from renewable cellulose resources, melt polycondensation of 5-hydroxylevulinic acid (5-HLA) was reported for the first time. The resulting product, poly(5-hydroxylevulinic acid) (PHLA), was synthesized and characterized with GPC, FTIR, 1H NMR and DSC. The in vitro degradation behaviors in phosphate-buffered saline (PBS) and in deionized water (DW) were also examined. The molecular weight of PHLA is not high (several 1,000s), but it possesses unordinary high glass transition temperature (as high as 120 °C). This is very different from existing aliphatic polyesters that usually have Tgs lower than 60 °C. The high Tg is attributed to the formation of inter- and/or intramolecular hydrogen bonds due to a characteristic keto–enol tautomerism equilibrium in the polymer structure. PHLA readily degraded hydrolytically in aqueous media.

Kinetics of methyl methacrylate and n-butyl acrylate copolymerization mediated by 2-cyanoprop-2-yl dithiobenzoate as a RAFT agent

Co-reporter:Jing Gao;Yingwu Luo;Rui Wang;Shiping Zhu

Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 14) pp:3098-3111

Publication Date(Web):6 JUN 2007

DOI:10.1002/pola.22067

The RAFT (co)polymerization kinetics of methyl methacrylate (MMA) and n-butyl acrylate (BA) mediated by 2-cyanoprop-2-yl dithiobenzoate was studied with various RAFT concentrations and monomer compositions. The homopolymerization of MMA gave the highest rate. Increasing the BA fraction f_BA dramatically decreased the copolymerization rate. The rate reached the lowest point at f_MMA ∼ 0.2. This observation is in sharp contrast to the conventional RAFT-free copolymerization, where BA homopolymerization gave the highest rate and the copolymerization rate decreased monotonously with increasing f_MMA. This peculiar phenomenon can be explained by the RAFT retardation effect. The RAFT copolymerization rate can be described by 〈R_p〉/〈R_p〉₀ = (1 + 2(〈k_c〉/〈k_t〉)〈K〉)[RAFT]₀)^−0.5, where 〈R_p〉₀ is the RAFT-free copolymerization rate and 〈K〉 is the apparent addition–fragmentation equilibrium coefficient. A theoretical expression of 〈K〉 based on a terminal model of addition and fragmentation reactions was derived and successfully applied to predict the RAFT copolymerization kinetics with the rate parameters obtained from the homopolymerization systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3098–3111, 2007

Preparation and SO2 Absorption/Desorption Properties of Crosslinked Poly(1,1,3,3-Tetramethylguanidine Acrylate) Porous Particles

Co-reporter:Zhengmin Zhang;Bo-Geng Li;Jie Dong;Shiping Zhu;Linbo Wu;Dong An

Macromolecular Rapid Communications 2006 Volume 27(Issue 22) pp:1949-1954

Publication Date(Web):16 NOV 2006

DOI:10.1002/marc.200600563

Summary: Novel crosslinked porous particles based on the ionic copolymer of 1,1,3,3-tetramethylguanidine acrylate (TMGA) and N,N-methylenebisacrylamide (MBA) were prepared via an inverse suspension polymerization using cyclohexane as continuous phase and Span 60 as the dispersant. The SO₂ absorption–desorption properties of the P(TMGA-co-MBA) particles were studied for the first time. The particles showed excellent SO₂ absorption properties: high capacity and rate. These absorption properties, as well as the particle volume, shape, and morphology, remained unchanged during the SO₂ absorption–desorption cycles. The material appeared to be a good candidate as SO₂ absorbent for fuel gas desulfurization (FGD) and purification of other SO₂-containing gases.

Design and Control of Copolymer Composition Distribution in Living Radical Polymerization Using Semi-Batch Feeding Policies: A Model Simulation

Co-reporter:Rui Wang;Xiaoying Sun;Yingwu Luo;Shiping Zhu

Macromolecular Theory and Simulations 2006 Volume 15(Issue 4) pp:356-368

Publication Date(Web):3 MAY 2006

DOI:10.1002/mats.200600007

Summary: Although controlled/living radical copolymerization has been extensively studied, the control of copolymer composition distribution receives little attention. In this paper, taking RAFT copolymerization as an example, we develop a mathematical model and simulate copolymerization systems with various reactivity ratios. It is demonstrated that through semi-batch operations with programmed profiles of slow monomer feeding rate, precise control over copolymer composition distribution (uniform and designed gradient distributions) along polymer chain can be achieved. It is also found that the semi-batch operations have lower rates of polymerization than their batch counterparts. The reason for this difference is analyzed, and the magnitude depends on the reactivity ratios and targeted copolymer composition. The improvement of the semi-batch rate by distributing a part of the initiator amount to the monomer feeding tank is found to be minor.

Effect of molecular weight and molecular weight distribution on cure reaction of novolac with hexamethylenetetramine and properties of related composites

Co-reporter:Jintao Wan, Songsong Wang, Cheng Li, Dapeng Zhou, Jianguo Chen, Zheng Liu, Liqiong Yu, Hong Fan, Bo-Geng Li

Thermochimica Acta (20 February 2012) Volume 530() pp:32-41

Publication Date(Web):20 February 2012

DOI:10.1016/j.tca.2011.11.032