Co-reporter:Quantao Li, Wenqiu Chen, Wei Yan, Quanyuan Zhang, Changfeng Yi, Xianbao Wang and Zushun Xu
RSC Advances 2016 vol. 6(Issue 1) pp:716-729
Publication Date(Web):08 Dec 2015
DOI:10.1039/C5RA21499H
Firstly, fully exfoliated graphene oxide (GO) colloidal dispersion in N-methyl-2-pyrrolidone (NMP) with high concentration is obtained by a solvent-exchange method and further used to prepare superior GO-MDI with free isocyanato groups by chemical modification. Then, the yielded GO-MDI is employed to prepare two kinds of MDI-modified graphene/hyperbranched poly(ether imide) (GE-MDI/HBPEI) nanocomposites via in situ random solution co-polycondensation or crosslinking reaction, followed by synchronous thermal imidization and reduction. The chemical modification of GO endows GO-MDI with good solubility in organic solvents to prepare GE-MDI/HBPEI nanocomposites with high filler content. GO-MDI is further used as a multi-functional co-monomer or crosslinker to be introduced into the HBPEI backbone with full compatibility of the guest and host at the molecular level. Finally, the performance tests show that the heat resistance, thermal stability, mechanical strength and modulus, and gas barrier properties of the obtained two kinds of nanocomposites are significantly improved or enhanced compared with pure HBPEI, and the impacts become more and more significant with the increase of GO-MDI content, but their mechanical toughness show trends of increase at first then decrease with the increase of GO-MDI content. Comparisons also show that at the same GO-MDI content, the heat resistance, thermal stability, mechanical strength and modulus of the nanocomposites obtained by in situ random solution co-polycondensation are all superior to those obtained by in situ random solution crosslinking reaction, except the mechanical toughness and gas barrier properties of the former are less than the latter. This effective approach provides a possibility for enriching and developing high performance PEI-based composites with various forms of GE for advanced engineering or functional materials.
Co-reporter:Wenqiu Chen;Quantao Li;Quanyuan Zhang;Zushun Xu;Xianbao Wang
Journal of Applied Polymer Science 2015 Volume 132( Issue 9) pp:
Publication Date(Web):
DOI:10.1002/app.41544
ABSTRACT
A series of amine-terminated and anhydride-terminated hyperbranched polyimides (HBPIs) were successfully prepared with various commercial dianhydrides and a novel BB′2-type aromatic triamine, 2,4,6-tris[4-(4-aminophenoxy)phenyl]pyridine, with a symmetrical triaryl-substituted pyridine segment and prolonged flexible linkages. The chemical structure of the triamine monomer and the hyperbranched structure of the resulting polymers were verified by Fourier transform infrared spectroscopy and 1H-NMR spectroscopy. The resulting HBPIs, which mainly held an amorphous morphology, exhibited improved organosolubilities in several strong polar aprotic solvents, good heat resistance with glass-transition temperature values in the range 218.6–311.0°C, and excellent thermal stabilities in both N2 and air [the temperature at 5% weight loss (T5%) in N2 was higher than 529.8°C and the T5% in air was higher than 465.1°C]. The obtained HBPI films also showed outstanding mechanical properties with tensile strength, tensile modulus, and elongation at break values of 86.4–101.3 MPa, 1.73–2.04 GPa, and 5.07–10.67%, respectively; considerable optical transparency; low water absorption; and neutral interface wettability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41544.
Co-reporter:Wen-Qiu Chen;Quan-Tao Li;Peng-Hui Li;Quan-Yuan Zhang
Journal of Materials Science 2015 Volume 50( Issue 11) pp:3860-3874
Publication Date(Web):2015 June
DOI:10.1007/s10853-015-8890-7
Reduced graphene oxide/polyimide (rGO/PI) nanocomposites are prepared via in situ random co-polycondensation of amino-modified and chemically reduced graphene oxide (rGO-NH2) with commercial diamine and dianhydrides. The chemical modification and reduction of graphene oxide (GO) endows rGO-NH2 with good solubility in organic solvents to prepare rGO/PI nanocomposites with high filler contents. rGO-NH2 is further used as a functional co-monomer to participate the polymerization of PI with full compatibility of the guest and host in molecular level. With the addition of rGO-NH2 at 2 wt% content, the thermal, mechanical properties, and hydrophobicities of rGO/PI nanocomposites are significantly enhanced with various indicators achieving or approaching the optimum. The positive or negative impacts of rGO-NH2 with various contents to the properties of the obtained nanocomposites are also illustrated incidentally from micromorphology. This effective approach provides a possibility for developing high-performance PI composites based on graphene for advanced engineering or functional materials.
Co-reporter:Ying Zhang, Jie Shen, Qing Li, Long Pang, Quanyuan Zhang, Zushun Xu, Kelvin W.K. Yeung, Changfeng Yi
Composites Part A: Applied Science and Manufacturing 2013 Volume 55() pp:161-168
Publication Date(Web):December 2013
DOI:10.1016/j.compositesa.2013.08.014
Novel hyperbranched polyimides/attapulgite (HBPI/AT) nanocomposites were successfully synthesized by in situ polymerization. HBPI derived from novel 2,4,6-tri[3-(4-aminophenoxy)phenyl]pyridine (TAPP) and 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA). 4,4′-diphenylmethane diisocyanate (MDI) modified AT copolymerized with HBPI and the nanocomposites formed multilinked network. Chemical structure, morphology, thermal behavior, and mechanical properties of nanocomposites were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile testing et.al. Results indicated that modified AT was homogeneously dispersed in matrix and resulted in an improvement of thermal stability, mechanical properties and water resistance of HBPI/AT nanocomposites.
Co-reporter:Jie Shen;Ying Zhang;Wenqiu Chen;Wenhao Wang;Zushun Xu;Kelvin W. K. Yeung
Journal of Polymer Science Part A: Polymer Chemistry 2013 Volume 51( Issue 11) pp:2425-2437
Publication Date(Web):
DOI:10.1002/pola.26628
ABSTRACT
Novel pyridine-containing hyperbranched polyimides (HBPIs) were synthesized by using a new triamine 2,4,6-tris[3-(4-aminophenoxy)phenyl]pyridine with prolonged chain segments, ether linkage and meta-linked units as a BB′2-like monomer, various commercial aromatic dianhydrides as A2 monomers. Most of the obtained HBPIs were readily soluble in common organic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, m-Cresol, and so forth. Meanwhile, they also had good thermal stability with the glass transition temperatures (Tgs) all above 210 °C, the temperature at 10% weight loss of 537.1–574.4 °C in nitrogen atmosphere. Strong and flexible HBPI films were obtained, which had good mechanical properties with tensile strengths of 83.3–95.8 MPa, tensile modulus of 1.82–2.43 GPa and elongations at break of 4.84–6.98%. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2425–2437
Co-reporter:Jie Shen;Ying Zhang;Mingfu Huang;Wenhao Wang;Zushun Xu
Journal of Polymer Research 2012 Volume 19( Issue 5) pp:
Publication Date(Web):2012 May
DOI:10.1007/s10965-012-9857-x
Novel reactive polyimides (PIs) containing phenolic hydroxyl functionalities were prepared from 4-(4-hydroxyphenyl)-2,6-bis[3-(4-aminophenoxy)phenyl]pyridine (m,p-HAPP) with various aromatic dianhydrides via one-step polycondensation procedure. The inherent viscosities of the PIs were 0.54–0.63 dL/g in DMF solution and most of them were readily soluble in common organic solvents such as DMF, DMAc, NMP, and m-Cresol, etc. Meanwhile, the PIs also had good thermal stability, with the glass transition temperature (Tg) of 221.7–310.5 °C, the temperature at 10 % weight loss of 524.1–579.3 °C in nitrogen atmosphere. Then commercial epoxy resin was cured in the presence of different ratios of the reactive polyimide, giving a series of polyimide modified epoxy films. Thermogravimetric analysis showed the increase of the temperature at 5 % weight loss of the films with the increase of the polyimide content; 296 °C for 0 %, 309 °C for 1.95 %, 337 °C for 3.85 % and 350 °C for 5.63 %.
Co-reporter:Shanyin Yan;Wenqiu Chen;Xiaojin Yang;Chuan Chen;Mingfu Huang
Polymer Bulletin 2011 Volume 66( Issue 9) pp:1191-1206
Publication Date(Web):2011 May
DOI:10.1007/s00289-010-0343-5
A novel pyridine-containing aromatic diamine monomer, 4-phenyl-2,6-bis[3-(4-aminophenoxy)phenyl]pyridine (m,p-PAPP), was successfully synthesized by a modified Chichibabin reaction of benzaldehyde and a substituted acetophenone, 3-(4-nitrophenoxy)acetophenone (m,p-NPAP), followed by a reduction of the resulting dinitro compound 4-phenyl-2,6-bis[3-(4-nitrophenoxy)phenyl]pyridine (m,p-PNPP) with Pd/C and hydrazine monohydrate. The aromatic diamine was employed to synthesize a series of pyridine-containing polyimides (PIs) by polycondensation with various aromatic dianhydrides in N,N-dimethylformamide (DMF) via the conventional two-step method, and further thermal or chemical imidization forming PIs. The inherent viscosities of the resulting poly(amic acid)s and PIs were 0.59–0.73 and 0.56–0.68 dL/g; most of the PIs obtained by chemical imidization were readily soluble in common organic solvents such as DMF, N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), etc. Meanwhile, strong and flexible PI films were obtained, which had good thermal stability, with the glass transition temperature (Tg) of 204.5–237.4 °C and the temperature at 10% weight loss of 527.7–552.0 °C in nitrogen atmosphere, as well as outstanding mechanical properties with tensile strengths of 88.6–90.4 MPa, a tensile moduli of 1.04–1.56 GPa, and elongations at break of 7.2–8.7%. The PI films also were found to possess low water uptake of 0.89–0.98%.
Co-reporter:W. Chen;W. Yan;S. Wu;Z. Xu;K. W. K. Yeung;C. Yi
Macromolecular Chemistry and Physics 2010 Volume 211( Issue 16) pp:1803-1813
Publication Date(Web):
DOI:10.1002/macp.201000193
Co-reporter:Quantao Li;Zushun Xu
Journal of Applied Polymer Science 2008 Volume 107( Issue 2) pp:797-802
Publication Date(Web):
DOI:10.1002/app.27136
Abstract
Polycondensation-type poly(amic acid) (PAA) was synthesized with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride as a dianhydride monomer and 4,4′-diaminodiphenylmethane and 4,4′-oxydianiline as diamine monomers under microwave irradiation in dimethylformamide. Then, PAA was used to make polyimide (PI) by imidization at a low temperature. The structure and performance of the polymers were characterized with Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H-NMR), viscosity, X-ray diffraction (XRD), and thermogravimetry (TG) curve analyses. The FTIR spectra of the polymers showed characteristic peaks of PI around 1779 and 1717 cm−1. The 1H-NMR spectrum of PAA indicated a singlet at 6.55 ppm assigned to NHCO and a singlet at 10.27 ppm assigned to carboxylic acid protons. The XRD spectrum demonstrated that the obtained PI had a low-order aggregation structure with a d-spacing of 0.5453 nm. The TG results revealed that the PI was thermally stable with 10% weight loss at 565°C in an N2 atmosphere. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Co-reporter:Z. W. Deng;X. X. Hu;L. Li;Z. S. Xu;C. F. Yi
Journal of Applied Polymer Science 2006 Volume 99(Issue 6) pp:3514-3519
Publication Date(Web):19 JAN 2006
DOI:10.1002/app.22977
The monodisperse poly(styrene-co-N-isopropylacrylamide) (poly(St-co-NIPAAm)) particles prepared by emulsifier-free emulsion polymerization with microwave irradiation were induced by capillary forces to self-assemble, and formed the two-dimensional films on the clean glassware wafer substrates. The morphologies of the two-dimensional films were characterized by scanning electron microscopy (SEM) and atom force microscopy (AFM). The results showed that monodisperse poly(St-co-NIPAAm) particles could form ordered two-dimensional films by capillary forces. With NIPAAm concentration increasing, there gradually appeared surface undulations or surface defective region on the two-dimensional films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3514–3519, 2006
Co-reporter:Jingjing Huang, Hui Pen, Zushun Xu, Changfeng Yi
Reactive and Functional Polymers (January 2008) Volume 68(Issue 1) pp:332-339
Publication Date(Web):January 2008
DOI:10.1016/j.reactfunctpolym.2007.08.002
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