Publications by authors named "Wantai Yang"

111 Publications

UV-Assisted Li-Catalyzed Radical Grafting Polymerization of Vinyl Ethers: A New Strategy for Creating Hydrolysis-Resistant and Long-Lived Polymer Brushes as a "Smart" Surface Coating.

Langmuir 2021 04 31;37(14):4102-4111. Epub 2021 Mar 31.

Beijing Engineering Research Center of Syntheses and Applications of Waterborne Polymers College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.

A facile synthetic route was developed to prepare a surface-grafted brush layer of poly(vinyl ethers) (PVEs) directly by a radical mechanism, with the "naked" Li acting as a catalyst. Density functional theory calculations suggested that complexation of naked Li to VEs significantly reduced the highest unoccupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap from 5.08 to 0.68 eV, providing a better prospect for electron transfer. The structure, morphology, and surface properties of grafted polymer layers were characterized using attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and dynamic water contact angle (DCA). Moreover, ellipsometry data indicated that the thickness of the polymer brushes was in the range of 20-60 nm, which corresponds to the grafting densities of 0.65-1.15 chain/nm, and DCA decreased from 84.4 to 45.3°. Most importantly, no hydrolysis was observed for the modified surface after 30 days of exposure to phosphate-buffered saline solution, 0.1 mol/L NaOH(eq) and 0.1 mol/L HCl(eq), demonstrating excellent hydrolysis resistance with long service life. In addition, as a proof of concept, the side hydroxyl groups of grafted PVEs provide active sites for efficient fixation of bioactive molecules, e.g., glycosaminoglycan and serum protein.
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http://dx.doi.org/10.1021/acs.langmuir.0c03480DOI Listing
April 2021

Anomalously Shaped Functional Particles Prepared by Thiol-Isocyanate Off-Stoichiometric Click Dispersion Polymerization.

Langmuir 2020 Dec 16;36(47):14417-14424. Epub 2020 Nov 16.

College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.

Anomalously shaped microparticles have attractive advantages in applications. They are usually prepared by chain-growth polymerizations in heterogeneous systems. Recently, thiol-X step-growth polymerizations have been used to produce functional particles with a regular shape but rarely anomalous shapes. Herein, we report the preparation of anomalously shaped particles by thiol-isocyanate dispersion polymerization (Dis.P) in ethanol using polyvinylpyrrolidone (PVP) as a stabilizer and catalyst. Papillae-shaped, raspberry-like, and multibulged particles are prepared by tuning monomer combinations, contents, and feed ratios. Particle morphology evolutions during polymerization are observed by scanning electron microscopy (SEM). Distinct from previous works, particles with residual -SH groups are obtained even with equal moles of monomers added initially. The residue of -SH groups is revealed by Fourier transform infrared spectroscopy (FT-IR) analyses and confirmed by detection with a fluorescent probe containing disulfide linkage. Moreover, fluorescent particle probes are formed by the reaction of excess -NCO groups on particles with fluorescein isothiocyanate isomer I (FITC) and dithioacetal-functionalized perylenediimide (DTPDI). The probes are sensitive in detection of glutathione (GSH) and Hg in water. Hg as low as 1-0.1 ppb is detected using a raspberry-like particle probe with DTPDI.
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http://dx.doi.org/10.1021/acs.langmuir.0c02798DOI Listing
December 2020

Antibacterial hydrogel coating: Strategies in surface chemistry.

Adv Colloid Interface Sci 2020 Nov 28;285:102280. Epub 2020 Sep 28.

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing 100029, China; Key Laboratory of Biomedical Materials of Natural Macromolecules, Ministry of Education Beijing, Beijing University of Chemical Technology, 100029, China; Beijing Advanced Innovation Centre for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China. Electronic address:

Hydrogels have emerged as promising antimicrobial materials due to their unique three-dimensional structure, which provides sufficient capacity to accommodate various materials, including small molecules, polymers and particles. Coating substrates with antibacterial hydrogel layers has been recognized as an effective strategy to combat bacterial colonization. To prevent possible delamination of hydrogel coatings from substrates, it is crucial to attach hydrogel layers via stronger links, such as covalent bonds. To date, various surface chemical strategies have been developed to introduce hydrogel coatings on different substrates. In this review, we first give a brief introduction of the major strategies for designing antibacterial coatings. Then, we summarize the chemical methods used to fix the antibacterial hydrogel layer on the substrate, which include surface-initiated graft crosslinking polymerization, anchoring the hydrogel layer on the surface during crosslinking, and chemical crosslinking of layer-by-layer coating. The reaction mechanisms of each method and matched pretreatment strategies are systemically documented with the aim of introducing available protocols to researchers in related fields for designing hydrogel-coated antibacterial surfaces.
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http://dx.doi.org/10.1016/j.cis.2020.102280DOI Listing
November 2020

Facile fabrication of shell crosslinked microcapsule by visible light induced graft polymerization for enzyme encapsulation.

Chem Commun (Camb) 2020 Jun;56(50):6862-6865

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China. and Beijing Laboratory of Biomedical Materials, Key Laboratory of Biomedical Materials of Natural Macromolecules, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China and Beijing Advanced Innovation Centre for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.

Immobilization of enzymes can effectively improve their stability, facilitate their recycling and reduce the cost, which is of great significance for the development of highly efficient biocatalysis technology. Here a simple strategy to encapsulate enzymes into polymeric microcapsules fabricated by visible light induced graft polymerization on a removable template was developed. The strategy showed a high degree of enzyme loading and excellent reusability of the immobilized enzyme.
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http://dx.doi.org/10.1039/d0cc02225jDOI Listing
June 2020

Fluorescence Self-Reporting Precipitation Polymerization Based on Aggregation-Induced Emission for Constructing Optical Nanoagents.

Angew Chem Int Ed Engl 2020 06 9;59(25):10122-10128. Epub 2020 Jan 9.

Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.

Precipitation polymerization is becoming increasingly popular in energy, environment and biomedicine. However, its proficient utilization highly relies on the mechanistic understanding of polymerization process. Now, a fluorescence self-reporting method based on aggregation-induced emission (AIE) is used to shed light on the mechanism of precipitation polymerization. The nucleation and growth processes during the copolymerization of a vinyl-modified AIEgen, styrene, and maleic anhydride can be sensitively monitored in real time. The phase-separation and dynamic hardening processes can be clearly discerned by tracking fluorescence changes. Moreover, polymeric fluorescent particles (PFPs) with uniform and tunable sizes can be obtained in a self-stabilized manner. These PFPs exhibit biolabeling and photosensitizing abilities and are used as superior optical nanoagents for photo-controllable immunotherapy, indicative of their great potential in biomedical applications.
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http://dx.doi.org/10.1002/anie.201913847DOI Listing
June 2020

Layered Co-Immobilization of β-Glucosidase and Cellulase on Polymer Film by Visible-Light-Induced Graft Polymerization.

ACS Appl Mater Interfaces 2019 Nov 12;11(47):44913-44921. Epub 2019 Nov 12.

Exploring a suitable immobilization strategy to improve catalytic efficiency and reusability of cellulase is of great importance to lowering the cost and promoting the industrialization of cellulose-derived bioethanol. In this work, a layered structure with a thin PEG hydrogel as the inner layer and sodium polyacrylate (PAANa) brush as the outer layer was fabricated on low density polyethylene (LDPE) film by visible-light-induced graft polymerization. Two enzymes, β-glucosidase (BG) and cellulase, were separately coimmobilized onto this hierarchical film. As supplementary to cellulase for improving catalytic efficiency, BG was in situ entrapped into the inner PEG hydrogel layer during the graft polymerization from the LDPE surface. After graft polymerization of sodium acrylate on the PEG hydrogel layer was reinitiated, cellulase was covalently attached on the outer PAANa brush layer. Owing to the mild reaction condition (visible-light irradiation and room temperature), the immobilized BG could retain a high activity after the graft polymerization. The immobilization did not alter the optimal pH and temperature of BG or the optimal temperature of cellulase. However, the optimal pH of cellulase shifts to 5.0 after immobilization. Compared with the original activity of single cellulase system and isolated BG/cellulase immobilization system, the dual-enzyme system exhibited 82% and 20% increase in catalytic activity, respectively. The dual-enzyme system could maintain 93% of carboxymethylcellulose sodium salt (CMC) activity after repeating 10 cycles of hydrolysis and 89% of filter paper activity after 6 cycles relative to original activity, exhibiting excellent reusability. This layer coimmobilization system of BG and cellulase on the polymer film displays tremendous potential for practical application in a biorefinery.
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http://dx.doi.org/10.1021/acsami.9b16274DOI Listing
November 2019

Self-Stabilized Precipitation Polymerization and Its Application.

Research (Wash D C) 2018 10;2018:9370490. Epub 2018 Sep 10.

College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.

An effective, value-added use of the large amounts of olefinic compounds produced in the processing of petroleum, aside from ethylene and propylene, has been a long outstanding challenge. Here, we developed a novel heterogeneous polymerization method, beyond emulsion/dispersion/suspension, termed self-stabilized precipitation (2SP) polymerization, which involves the nucleation and growth of nanoparticles (NPs) of a well-defined size without the use of any stabilizers and multifunctional monomers (crosslinker). This technique leads to two revolutionary advances: (1) the generation of functional copolymer particles from single olefinic monomer or complex olefinic mixtures (including C4/C5/C9 fractions) in large quantities, which open a new way to transform huge amount of unused olefinic compounds in C4/C5/C9 fractions into valuable copolymers, and (2) the resultant polymeric NPs possess a self-limiting size and narrow size distribution, therefore being one of the most simple, efficient, and green strategies to produce uniform, size-tunable, and functional polymeric nanoparticles. More importantly, the separation of the NPs from the reaction medium is simple and the supernatant liquid can be reused; hence this new synthetic strategy has great potential for industrial production.
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http://dx.doi.org/10.1155/2018/9370490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750106PMC
September 2018

Highly Transparent Cyclic Olefin Copolymer Film with a Nanotextured Surface Prepared by One-Step Photografting for High-Density DNA Immobilization.

ACS Appl Mater Interfaces 2019 Aug 31;11(32):28690-28698. Epub 2019 Jul 31.

Compared with conventional glass slides and two-dimensional (2D) planar microarrays, polymer-based support materials and three-dimensional (3D) surface structures have attracted increasing attention in the field of biochips because of their good processability in microfabrication and low cost in mass production, as well as their improved sensitivity and specificity for the detection of biomolecules. In the present study, UV-induced emulsion graft polymerization was carried out on a cyclic olefin copolymer (COC) surface to generate 3D nanotextures composed of loosely stacked nanoparticles with a diameter of approximately 50 nm. The introduction of a hierarchical nanostructure on a COC surface only resulted in a 5% decrease in its transparency at a wavelength of 550 nm but significantly increased the surface area, which markedly improved immobilization density and efficiency of an oligonucleotide probe compared with the functional group and polymer brush-modified substrates. The highest immobilization efficiency of the probes reached 93%, and a limit of detection of 75 pM could be obtained. The hybridization experiment demonstrated that the 3D gene chip exhibited excellent sensitivity for target DNA detection and single-nucleotide polymorphism discrimination. This one-step approach to the construction of nanotextured surfaces on the COC has promising applications in the fields of biochips and immunoassays.
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http://dx.doi.org/10.1021/acsami.9b09662DOI Listing
August 2019

Polymer Materials Research at CMSE.

Macromol Rapid Commun 2018 10;39(20):e1800683

College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, China.

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http://dx.doi.org/10.1002/marc.201800683DOI Listing
October 2018

Extremely High Glass Transition Temperature Hydrocarbon Polymers Prepared through Cationic Cyclization of Highly 3,4-Regulated Poly(Phenyl-1,3-Butadiene).

Macromol Rapid Commun 2018 Oct 7;39(20):e1800298. Epub 2018 Aug 7.

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.

A simple approach to synthesize extremely high glass transition temperature (Tg > 300 °C) hydrocarbon polymers that introduces bridged cyclic backbone and bulky pendant group simultaneously is reported. This method uses highly 3,4-regulated poly(phenyl-1,3-butadiene) as a prepolymer for cationic cyclization postmodification. The Tg of cyclized highly 3,4-regulated (94.0%) poly(1-phenyl-1,3-butadiene) (P(1-PB)) can reach 304 °C. To further restrict the movement of bridged cyclic backbone by changing the position of the pendant substituent group, highly 3,4-regulated (96.2%) poly(2-phenyl-1,3-butadiene) (P(2-PB)) is used as the prepolymer. The Tg of its cyclized product reaches 325 °C, and this value is the highest ever reported among all hydrocarbon polymers. The results indicate that the regularity of poly(phenyl-1,3-butadiene) and the pendant substituent group are crucial factors when synthesizing high-temperature hydrocarbon polymers through this approach.
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http://dx.doi.org/10.1002/marc.201800298DOI Listing
October 2018

Nacre-like laminate nitrogen-doped porous carbon/carbon nanotubes/graphene composite for excellent comprehensive performance supercapacitors.

Nanoscale 2018 Aug;10(32):15229-15237

College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China.

A nitrogen-doped porous carbon/carbon nanotubes/graphene (PGMC) composite was prepared through a process of hydrothermal treatments, polymerization of o-phenylenediamine (OPD), and pyrolysis. The as-prepared PGMC composite was found to be of a nacre-like laminate porous structure, constructed with alternatively stacked two-dimensional (2D) graphene sheets and porous carbons, and also interspersed within one-dimensional (1D) multi-walled carbon nanotubes (MWNTs). The MWNTs effectively suppressed agglomeration of graphene sheets during the hydrothermal process and were interspersed in PGMC to help construct more networks with excellent conductivity. The PGMC possessed an enriched nitrogen doping ratio of 15.67 at% and relative high density of 1.39 g cm-3. The electrode composed of PGMC provided high gravimetric capacitance of 562.9 F g-1 and volumetric capacitance of 782.4 F cm-3 at current density of 1 A g-1, as well as excellent rate capability and cycling stability. The symmetric supercapacitors mounted with the as-prepared PGMC electrode were stably operated in a wide potential range of 0-1.3 V and demonstrated a superb gravimetric energy density of 19.79 W h kg-1 at high power density of 650 W kg-1, and a high volumetric energy density of 27.51 W h L-1 with a power density of 904 W L-1. The outstanding electrochemical performance enables this as-prepared nacre-like laminate PGMC composite to be a promising candidate for energy storage application.
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http://dx.doi.org/10.1039/c8nr02439aDOI Listing
August 2018

Cytocompatible Fabrication of Yeast Cells/Fabrics Composite Sheet for Bioethanol Production.

Macromol Rapid Commun 2018 Oct 26;39(20):e1800212. Epub 2018 Jun 26.

State Key Laboratory of Chemical Resource Engineering, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing, 100029, China.

Entrapment of living cells into a polymer network has significant potential in various fields such as biomass conversion and tissue engineering. A crucial challenge for this strategy is to provide a mild enough condition to preserve cell viability. Here, a facile and cytocompatible method to entrap living yeast cells into a poly(ethylene glycol) (PEG) network grafting from polypropylene nonwoven fabrics via visible-light-induced surface living graft crosslinking polymerization is reported. Due to the mild reaction conditions and excellent biocompatibility of PEG, the immobilized yeast cells could maintain their viability and proliferate well. The obtained composite sheet has excellent long-term stability and shows no significant efficiency loss after 25 cycles of repeated batch bioethanol fermentation. The immobilized yeast cells exhibit 18.0% higher bioethanol fermentation efficiency than free cells. This strategy for immobilization of living cells with high viability has significant potential application.
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http://dx.doi.org/10.1002/marc.201800212DOI Listing
October 2018

High-Performance Biomass-Based Flexible Solid-State Supercapacitor Constructed of Pressure-Sensitive Lignin-Based and Cellulose Hydrogels.

ACS Appl Mater Interfaces 2018 Jul 19;10(26):22190-22200. Epub 2018 Jun 19.

Department of Polymer Science , Beijing University of Chemical Technology , Beijing 100029 , P. R. China.

Employing renewable, earth-abundant, environmentally friendly, low-cost natural materials to design flexible supercapacitors (FSCs) as energy storage devices in wearable/portable electronics represents the global perspective to build sustainable and green society. Chemically stable and flexible cellulose and electroactive lignin have been employed to construct a biomass-based FSC for the first time. The FSC was assembled using lignosulfonate/single-walled carbon nanotube (Lig/SWCNT) pressure-sensitive hydrogels as electrodes and cellulose hydrogels as an electrolyte separator. The assembled biomass-based FSC shows high specific capacitance (292 F g at a current density of 0.5 A g), excellent rate capability, and an outstanding energy density of 17.1 W h kg at a power density of 324 W kg. Remarkably, the FSC presents outstanding electrochemical stability even suffering 1000 bending cycles. Such excellent flexibility, stability, and electrochemical performance enable the designed biomass-based FSCs as prominent candidates in applications of wearable electronic devices.
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http://dx.doi.org/10.1021/acsami.8b05171DOI Listing
July 2018

Decorating an individual living cell with a shell of controllable thickness by cytocompatible surface initiated graft polymerization.

Chem Commun (Camb) 2018 May;54(37):4677-4680

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.

Surface engineering of individual living cells is a promising field for cell-based applications. However, engineering individual cells with controllable thickness by chemical methods has been rarely studied. This article describes the development of a new cytocompatible chemical strategy to decorate individual living cells. The thicknesses of the crosslinked shells could be conveniently controlled by the irradiation time, visible light intensity, or monomer concentration. Moreover, the lag phase of the yeast cell division was extended and their stability against lysis was improved, which could also be tuned by controlling the shell thickness.
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http://dx.doi.org/10.1039/c8cc01311jDOI Listing
May 2018

Synthesis of hypergrafted poly[4-(N,N-diphenylamino)methylstyrene] through tandem anionic-radical polymerization of radical-inimer.

Des Monomers Polym 2017 30;20(1):476-484. Epub 2017 Aug 30.

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, P.R. China.

In this paper, we present a tandem anionic-radical approach for synthesizing hypergrafted polymers. We prepared 4-(N,N-diphenylamino)methylstyrene (DPAMS) as a new radical-based inimer. Linear PDPAMS was prepared through anionic polymerization. Hypergrafted PDPAMS was synthesized through the self-condensing vinyl polymerization of DPAMS with linear PDPAMS. The linear backbone of PDPAMS, which incorporated latent radical initiating sites, served as a 'hyperlinker' to link hyperbranched side chains. The molecular weights of hypergrafted polymers increased as the length of the linear backbone chain increased. The hypergrafted structure of the resulting polymer was confirmed using a conventional gel permeation chromatograph apparatus equipped with a multiangle light scattering detector, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. This strategy can be applied to synthesize other complex architectures based on hyperbranched polymers by changing the structure of a polymer backbone through anionic polymerization.
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http://dx.doi.org/10.1080/15685551.2017.1365577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5784871PMC
August 2017

Separated Immobilization of Incompatible Enzymes on Polymer Substrate via Visible Light Induced Living Photografting Polymerization.

Langmuir 2017 06 25;33(22):5577-5584. Epub 2017 May 25.

State Key Laboratory of Chemical Resource Engineering, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology (BUCT) , P.O. Box 37, Beijing 100029, China.

The use of the mixed catalytic system with several enzymes can provide multiple benefits in terms of the cost, simplification of a multistep reaction, and effectiveness of complex chemical reactions. Although study of different enzyme coimmobilization systems has attracted increasing attention in recent years, separately immobilizing enzymes which can not coexist on one support is still one of the great challenges. In this paper, a simple and effective strategy was introduced to separately encapsulate incompatible trypsin and transglutaminase (TGase) into different poly(ethylene glycol) (PEG) network layer grafted on low-density polyethylene (LDPE) film via visible light induced living photografting polymerization. As a proof of concept, this dual-enzyme separately loaded film was used to catalyze the synthesis of a new target antitumor drug LTV-azacytidine. The final results demonstrated that this strategy could maintain higher activities of both enzymes than the mixed coimmobilization method. And the mass spectra analysis results demonstrated that LTV-azacytidine was successfully synthesized. We believe that this facile and mild separately immobilizing incompatible enzyme strategy has great application potential in the field of biocatalysis.
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http://dx.doi.org/10.1021/acs.langmuir.7b00594DOI Listing
June 2017

Study on Hydrogen Sensitivity of Ziegler⁻Natta Catalysts with Novel Cycloalkoxy Silane Compounds as External Electron Donor.

Polymers (Basel) 2016 Dec 16;8(12). Epub 2016 Dec 16.

Petrochemical Research Institute, PetroChina, Beijing 102206, China.

Two novel cycloalkoxy silane compounds (ED1 and ED2) were synthesized and used as the external electron donors (EEDs) in Ziegler⁻Natta catalysts with diethyl 2,3-diisopropylsuccinate as internal electron donor. The results indicated that the Ziegler⁻Natta catalysts using ED1 and ED2 as EEDs had high catalytic activities and good stereoselectivities. The melt flow rate (MFR) and gel permeation chromatography (GPC) results revealed that the obtained polypropylene has higher MFR and lower average molecular weights than the commercial EED cyclohexyl methyl dimethoxysilane. The differential scanning calorimetry (DSC) results indicated that new isospecific active centers formed after the introduction of new external donors. The work implied that the novel EEDs could improve the hydrogen sensitivities of the catalyst system and obtain polymers with high melt flow rate.
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http://dx.doi.org/10.3390/polym8120433DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6432079PMC
December 2016

Metal-Organic Coordination Polymer to Prepare Density Controllable and High Nitrogen-Doped Content Carbon/Graphene for High Performance Supercapacitors.

ACS Appl Mater Interfaces 2017 Jan 27;9(1):317-326. Epub 2016 Dec 27.

Department of Polymer Science, Beijing University of Chemical Technology , Beijing, 100029, P. R. China.

Design and preparation of carbon-based electrode material with high nitrogen-doping ratio and appropriate density attract much interest for supercapacitors in practical application. Herein, three porous carbon/graphene (NCG, NCG, and NCG) with high doping ratio of nitrogen have been prepared via directly pyrolysis of graphene oxide (GO)/metal-organic coordination polymer (MOCP) composites, which were formed by reacting 4,4'-bipyridine (BPD) with CuCl, FeCl, and ZnCl, respectively. As-prepared NCG, NCG and NCG showed high nitrogen doping ratio of 10.68, 12.99, and 11.21 at. %; and high density of 1.52, 0.84, and 1.15 g cm, respectively. When as-prepared samples were used as supercapacitor electrodes, NCG, NCG and NCG exhibited high gravimetric specific capacitances of 369, 298.5, 309.5 F g, corresponding to high volumetric specific capacitances of 560.9, 250.7, 355.9 F cm at a current density of 0.5 A g, as well as good cycling stability, nearly 100% of the capacitance retained after 1000 cycles even at a large current density of 10 A g. It is expected that the provided novel strategy can be used to develop electrode materials in high performance energy conversion/storage devices.
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http://dx.doi.org/10.1021/acsami.6b10201DOI Listing
January 2017

Tunable Morphology of Spiropyran Assemblies: From Nanospheres to Nanorods.

Chem Asian J 2016 Nov 12;11(21):3102-3106. Epub 2016 Oct 12.

State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing, 100029, China.

Spiropyran (SP), which can respond to acid, ultraviolet irradiation, and mechanical force, has received great attention as a classic molecule for the construction of stimuli-responsive materials. However, the self-assembly behavior of SP with a tunable morphology has rarely been investigated. In the present work, a SP derivative bearing two carboxyl groups and one hydroxyl group was prepared and used as a model to investigate the optical properties, molecular self-assembly, and morphology of SP. This pH-responsive derivative could undergo a large morphology variation from a sphere- to a rodlike structure by adjusting the acidity. The indoline and pyridopyran fragments contributed to π-π stacking, whereas the carboxyl groups contributed to hydrogen bonding. Both π-π stacking and hydrogen bonding contributed to the pH-responsive self-assembly. The morphologies of spiropyran aggregates formed under different conditions were characterized by SEM, TEM, and FTIR spectroscopy. Control of the morphology of the spiropyran nanostructure was achieved.
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http://dx.doi.org/10.1002/asia.201601114DOI Listing
November 2016

Anionic polymerization of -(2,2'-diphenylethyl)styrene and applications to graft copolymers.

Des Monomers Polym 2017 21;20(1):66-73. Epub 2016 Sep 21.

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, PR China.

Well-controlled anionic polymerization of an initiator-functionalized monomer, -(2,2'-diphenylethyl)styrene (DPES), was achieved for the first time. The polymerization was performed in a mixed solvent of cyclohexane and tetrahydrofuran (THF) at 40 °C with -BuLi as initiator. When the volume ratio of cyclohexane to THF was 20, the anionic polymerization of DPES showed living polymerization characteristics, and well-defined block copolymer PDPES--PS was successfully synthesized. Furthermore, radical polymerization of methyl methacrylate in the presence of PDPES effectively afforded a graft copolymer composed of a polystyrene backbone and poly(methyl methacrylate) branches. The designation of analogous monomers and polymers was of great significance to synthesize a variety of sophisticated copolymer and functionalize polymer materials.
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http://dx.doi.org/10.1080/15685551.2016.1231044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5812173PMC
September 2016

Hierarchical PEG-Based 3D Patterns Grafting from Polymer Substrate by Surface Initiated Visible Light Photolithography.

Macromol Rapid Commun 2016 Oct 9;37(19):1611-1617. Epub 2016 Aug 9.

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.

The precise construction of a hierarchical complex pattern on substrates is required for numerous applications. Here, a strategy to fabricate well-defined hierarchical three dimensional (3D) patterns on polymer substrate is developed. This technique, which combines photolithography and visible light-induced surface initiated living graft crosslinking polymerization (VSLGCP), can effectively graft 3D patterns onto polymer substrate with high fidelity and controllable height. Owing to the living nature of VSLGCP, hierarchical 3D patterns can be prepared when a sequential living graft crosslinking process is performed on the first formed patterns. As a proof-of-concept, a reactive two layer 3D pattern with a morphology of lateral stripe on vertical stripe is prepared and employed to separately immobilize model biomolecules, e.g., biotin and IgG. This two component pattern can specifically interact with corresponding target proteins successfully, indicating that this strategy has potential applications in the fabrication of polymer-based multicomponent biomolecule microarrays.
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http://dx.doi.org/10.1002/marc.201600307DOI Listing
October 2016

A Cyanine Dye Encapsulated Porous Fibrous Mat for Naked-Eye Ammonia Sensing.

Chem Asian J 2016 Aug 3;11(16):2316-21. Epub 2016 Aug 3.

State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing, 100029, China.

Electrospun ultrathin fiber-based sensors are desirable because of their practicality and sensitivity. Ammonia-detection systems are in high demand in different areas, including the industrial and agricultural fields. However, current technologies rely on large and complex instruments that restrict their actual utilization. Herein, we report a flexible naked-eye ammonia sensor, the polylactic acid-cyanine (PLA-Cy) fibrous mat, which was fabricated by blending a carboxyl-functionalized cyanine dye (D1) into electospun PLA porous fibers. The sensing mat was shown to undergo a naked-eye-detectable color change from white to blue upon exposure to ammonia vapor. The mat showed high selectivity to ammonia gas with a detection limit of 3.3 ppm. Aggregated D1 was first encapsulated by PLA and was then ionized by NH3 . These mechanisms were examined by photophysical studies and scanning electron microscopy. The aggregation-deaggregation process of D1 in the PLA-Cy fibrous mat led to the color change. This work provides a facile method for the naked-eye detection of ammonia and a novel strategy for the use of organic dyes in ammonia sensing.
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http://dx.doi.org/10.1002/asia.201600818DOI Listing
August 2016

Effective approach towards Si-bilayer-IDA modified CoFe2O4 magnetic nanoparticles for high efficient protein separation.

Colloids Surf B Biointerfaces 2016 Oct 25;146:468-74. Epub 2016 Jun 25.

State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, 100029 Beijing, China. Electronic address:

Ultrafine cobalt ferrite (CoFe2O4) nanoparticles with narrow size distributions and regular morphologies were prepared through an improved procedure based on the high-temperature diol reduction method. By replacing the original reducing agent like expensive dihydric alcohol, oleylamine was applied as both stabilizer and reducing agent, which benefit for large scale synthesis of magnetic CoFe2O4 nanoparticles. To produce protein-separation agent with both high specific surface area and magnet content, inverse microemulsion system and substitution reaction were employed to render the produced CoFe2O4 nanoparticles with dense silica bilayer and iminodiacetic acid (IDA)-like structure modification. After the chelation with Cu(2+), the metal-immobilized CoFe2O4 nanoparticles can specifically absorb bovine hemoglobin (BHb) with maximum adsorption capacity as qm=1812.3mg/g. Compared with the reported Cu(2+)-immobilized magnetic nanoparticles, the as-prepared CoFe2O4@Si-IDA-Cu(2+) nanoparticles exhibited excellent adsorption capacity and were applied as high efficient protein separation agent in a real complex biological fluid like bovine blood.
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http://dx.doi.org/10.1016/j.colsurfb.2016.06.043DOI Listing
October 2016

Ammonium-Functionalized Hollow Polymer Particles As a pH-Responsive Adsorbent for Selective Removal of Acid Dye.

ACS Appl Mater Interfaces 2016 Jul 23;8(26):16690-8. Epub 2016 Jun 23.

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Beijing, China.

In this work, a novel type of ammonium-functionalized hollow polymer particles (HPP-NH3(+)) with a high density of ammonium groups in the shell has been specially designed and synthesized. Benefiting from both the high surface area and from the high density of positively charged ammonium groups, the as-prepared HPP-NH3(+) can serve as a selective adsorbent for the removal of negatively charged acid dye (e.g., methyl blue a-MB). The equilibrium adsorption data of a-MB on the HPP-NH3(+) were evaluated using Freundlich and Langmuir isotherm models, and Langmuir isotherm exhibited a better fit with a maximum adsorption capacity of 406 mg/g. Most importantly, because of the presence of dual functional groups (ammonium and carboxyl groups), the HPP-NH3(+) showed a significant pH-dependent equilibrium adsorption capacity, which increased dramatically from 59 mg/g to 449 mg/g as the solution pH decreased from 9 to 2. This uniqueness makes the dye-adsorbed HPP-NH3(+) can be facilely regenerated under mild condition (in weak alkaline solution, pH 10) to recover both a-MB and the HPP-NH3(+), whereas the recovery of conventional adsorbents is commonly performed under particularly severe conditions. The regenerated HPP-NH3(+) can be reused for dye removal and the dye removal efficiency remained above 98% even after five adsorption-desorption cycles. Because of its high adsorption capacity, pH-sensitivity, easy regeneration, and good reusability, the HPP-NH3(+) has great potential for the application in the field of water treatment, controlled drug release, and pH-responsive delivery.
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http://dx.doi.org/10.1021/acsami.6b04199DOI Listing
July 2016

Net-Immobilization of β-glucosidase on Nonwoven Fabrics to Lower the Cost of "Cellulosic Ethanol" and Increase Cellulose Conversions.

Sci Rep 2016 Mar 24;6:23437. Epub 2016 Mar 24.

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.

The main limitation preventing the use of enzymatic cellulosic ethanol in industrial production is its higher cost which is mainly due to the elevated price of β-glucosidase (BG). Herein, we report on a simple strategy for the in-situ encapsulation of BG for repeated cellulosic ethanol production. In this strategy, BG was net-immobilized into a poly(ethylene glycol) (PEG) net-cloth layer on a PP nonwoven fabric by way of the visible light-induced surface controlled/living graft cross-linking polymerization. The visible light and mild reaction conditions could ensure the activity retention of BG during immobilization, while the non-swelling uniform net-mesh formed by living cross-linking polymerization could prevent the leakage of BG effectively (at the immobilization rate of more than 98.6% and the leakage rate of only 0.4%). When the BG-loaded fabric was used in combination with free cellulase (CEL), the results of the catalytic reaction demonstrated that these BG-loaded fabrics could not only give a 40% increase in cellulose conversions but also be reused for more than fifteen batches without losing the activity. These BG-loaded fabrics with characteristics including easy separation, excellent operation stability, a low cost of the polymeric matrix and a simple fabrication process are particularly interesting for a future bio-fuel production strategy.
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http://dx.doi.org/10.1038/srep23437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4806303PMC
March 2016

Highly Active Copolymerization of Ethylene and -Acetyl--(ω-Alkenyl)-l-Tyrosine Ethyl Esters Catalyzed by Titanium Complex.

Polymers (Basel) 2016 Mar 10;8(3). Epub 2016 Mar 10.

State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, the College of Material Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.

A series of -acetyl--(ω-alkenyl)-l-tyrosine ethyl esters were synthesized by the reaction of vinyl bromides (4-bromo-1-butene, 6-bromo-1-hexene, 8-bromo-1-octene and 10-bromo-1-decene) with -acetyl-l-tyrosine ethyl ester. ¹H NMR, elemental analysis, FT-IR, and mass spectra were performed for these -acetyl--(ω-alkenyl)-l-tyrosine ethyl esters. The novel titanium complex can catalyze the copolymerization of ethylene and -acetyl--(ω-alkenyl)-l-tyrosine ethyl esters efficiently and the highest catalytic activity was up to 6.86 × 10⁴ gP·(molTi)·h. The structures and properties of the obtained copolymers were characterized by FT-IR, (¹H)C NMR, GPC, DSC, and water contact angle. The results indicated that the obtained copolymers had a uniformly high average molecular weight of 2.85 × 10⁵ g·mol and a high incorporation ratio of -acetyl--(but-3-enyl)-l-tyrosine ethyl ester of 2.65 mol % within the copolymer chain. The units of the comonomer were isolated within the copolymer chains. The insertion of the polar comonomer into a copolymer chain can effectively improve the hydrophilicity of a copolymer.
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http://dx.doi.org/10.3390/polym8030064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6432566PMC
March 2016

Fluorescent supramolecular micelles for imaging-guided cancer therapy.

Nanoscale 2016 Mar;8(9):5302-12

State Key Laboratory of Chemical Resource Engineering, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, 100029, Beijing, China.

A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth-inhibitory studies reveal a better therapeutic effect of FSMs after CPT encapsulation when compared with the free CPT drug. The multifunctional FSM nanomedicine platform as a nanovehicle has great potential for fluorescence imaging-guided cancer therapy.
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http://dx.doi.org/10.1039/c6nr00450dDOI Listing
March 2016

Development of an Amino Acid-Functionalized Fluorescent Nanocarrier to Deliver a Toxin to Kill Insect Pests.

Adv Mater 2016 Feb 7;28(7):1375-80. Epub 2015 Dec 7.

Department of Entomology, China Agricultural University, 100193, Beijing, China.

Large-scale cultivation of Bacillus thuringiensis Berliner (Bt) crops has led to the rapid development of drug resistance. Herein, a fluorescent star poly(amino acid) is synthesized with l-isoleucine functionalization for the efficient delivery of either positively or negatively charged exogenous proteins into live cells. Poly(amino acid)s (P1)/Cry1Ab complexes greatly increase the cytotoxicity of the Bt toxin, Cry1Ab, and efficiently kill Bt-resistant pests.
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http://dx.doi.org/10.1002/adma.201504993DOI Listing
February 2016

Synthesis of pH-responsive hydrogel thin films grafted on PCL substrates for protein delivery.

J Mater Chem B 2015 Oct 4;3(39):7673-7681. Epub 2015 Sep 4.

Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing 100029, China.

A new visible light induced graft polymerization method was utilized to prepare pH-sensitive hydrogel layers covalently attached to polymer substrates for drug delivery. In our strategy, isopropyl thioxanthone semi-pinacol (ITXSP) dormant groups were firstly introduced on the surface of a polycaprolactone (PCL) film by a UV-induced abstracting hydrogen-coupling reaction. Then visible light induced graft cross-linking polymerization was performed to initiate polymerization of poly(ethylene glycol) diacrylate (PEGDA) and acrylic acid (AA), resulting in the formation of a hydrogel layer. The thickness of the hydrogel film can be controlled by varying the exposure time and monomer composition. The grafted hydrogel layers showed a flat morphology and dense structure, which is different from the traditional reported porous structure. The water contact angle of the hydrogel layer exhibited a reversible change from 38° to 18° when the film was alternatively treated in buffers of pH 2.0 and 7.4, respectively. Patterned hydrogel layers were prepared as a model to determine the change in the height of the grafted hydrogel layer as a function of pH. As the pH changed from 2.0 to 7.4, the hydrogel pattern showed an increase in height due to the swelling of the hydrogel network, and the hydrogel layer formed by 0.2 wt% PEGDA and 25 wt% AA showed the most increase (30%) in height. Bovine serum albumin (BSA) and lysozyme as models of protein drugs were incorporated in the hydrogel network, and their release also showed obvious pH-sensitivity. At pH 2.0, hydrogels present a faster initial burst release due to the squeezing mechanism. Tertiary structure analysis showed that encapsulation and release did not affect the protein conformation. These findings have improved our understanding of hydrogel thin films, which may be useful as potential vehicles of therapeutic proteins in drug delivery applications.
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http://dx.doi.org/10.1039/c5tb01149cDOI Listing
October 2015

An amphiphilic squarylium indocyanine dye for long-term tracking of lysosomes.

J Mater Chem B 2015 Oct 14;3(38):7494-7498. Epub 2015 Sep 14.

State Key Laboratory of Chemical Resource Engineering, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, 100029 Beijing, China.

A novel amphiphilic squarylium indocyanine (LysoCy) is reported for remarkable lysosome tracking in live cells. LysoCy performs as a promising lysosome tracker with low cytotoxicity, a strong binding affinity and clear subcellular labelling. The long-term dynamics of lysosomes can be revealed by LysoCy for up to 2 days of culture, while the working duration of commercial dye is no longer than 1 hour. Our work provides a good alternative tool for long-term live cell imaging.
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http://dx.doi.org/10.1039/c5tb01738fDOI Listing
October 2015