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DongCheng Sun

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Name: 孙东成; Sun, DongCheng
Organization: South China University of Technology , China
Department:
Title: Associate Professor(PhD)
Preparation and properties of reactive polyurethane polyacrylate blends based on carbonyl-hydrazide reaction
Co-reporter:Guang Chai
Journal of Applied Polymer Science 2017 Volume 134(Issue 6) pp:
Publication Date(Web):2017/02/10
DOI:10.1002/app.44443
ABSTRACTA new reactive polyurethane/polyacrylate (PU/PA) blend was developed by mixing a core–shell polyacrylate latex containing keto groups in shell layer and a polyurethane dispersion incorporating multiple hydrazide groups which was synthesized by introducing the poly-hydrazide groups into the end of the vinyl-terminated polyurethane chains. Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) results indicated that poly-hydrazide groups had been incorporated in the polyurethane chains. Transmission electron microscopy (TEM) micrograph revealed that polyacrylate particles had a clear core–shell structure. The results of FTIR, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) indicated that the crosslinking reaction between two polymer systems had happened and crosslinking structure could effectively improve the compatibility between PA and PU. Thermogravimetric analysis (TGA) and mechanical tests results suggested that crosslinking structure could enhance the thermal stability and mechanical properties of blends. The influence of the PA content and the n(CO)/n(NHNH2) ratio on the hardness, water resistance, solvent resistance, and gel fraction of the blend films were comprehensively studied. The optimal PA content and n(CO)/n(NHNH2) ratio was 30% and 1.5:1 in this experiment, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44443.
Synthesis and characterization of ambient-temperature self-crosslinked waterborne polyurethanes with a novel diol chain extender bearing two ketone groups
Co-reporter:Mali Liao
Journal of Coatings Technology and Research 2016 Volume 13( Issue 4) pp:667-676
Publication Date(Web):2016 July
DOI:10.1007/s11998-015-9773-1
A series of ambient-temperature self-crosslinked waterborne polyurethanes denoted as WBPUs were successfully synthesized by incorporating a novel diol chain extender bearing two ketone groups, 2,2-bis(4-(2-hydroxypropoxy levulinate)phenyl)-propane (BHLPP), which was prepared using 2,2-bis(4-(2,3-epoxypropoxy)phenyl)-propane and levulinic acid, with 4,4-methylenedicyclohexyl diisocyanate, poly-neopentylene adipate glycol, and dimethylolpropionic acid. After post-adding adipic dihydrazide (ADH), self-crosslinking was achieved by the reaction between the ketone (–CO–) of BHLPP and the hydrazine (–NHNH2) of ADH during film formation. For comparison, noncrosslinked waterborne polyurethane (WPU) without BHLPP and ADH was prepared. The structure of BHLPP was characterized by IR and NMR. The properties of the WPU and WBPU dispersions were investigated by measuring the stability, particle size, and morphology. The effects of the ratio of n(–NHNH2)/n(–CO–) and the content of BHLPP were studied in terms of hardness, water resistance, solvent resistance, and thermal properties of WPU and WBPU films. The WBPU dispersions exhibited excellent stability, bimodal distribution, and regular spheroid morphology. The optimal ratio of n(–NHNH2)/n(–CO–) for ketone–hydrazine self-crosslinking was 0.75:1. Importantly, the WBPU films showed superior hardness, water resistance, solvent resistance, and thermal properties to WPU film.
Synthesis of high-solid content sulfonate-type polyurethane dispersion by pellet process
Co-reporter:Lina He
Journal of Applied Polymer Science 2013 Volume 127( Issue 4) pp:2823-2831
Publication Date(Web):
DOI:10.1002/app.37618

Abstract

A novel method to prepare polyurethane dispersions (PUDs) is introduced in this article. Water dispersible polyurethane ionomer pellets were synthesized without solvent; these pellets were then dissolved in acetone and dispersed in water. Then PUDs were obtained after acetone was distilled off. Polyurethane ionomers were synthesized from polyether diol containing sulfonate as hydrophilic monomer and poly(1,4-butylene adipate glycol) with an average molecular weight of 3000 as soft segments, isophorone diisocyanate and 1,4-butanediol as hard segments, and dibutyltin dilaurate as catalyst. The properties of PUDs were measured by Laser particle size analyzer, Brookfield viscosity, and TEM analysis. High-solid content and low viscosity PUDs were obtained. Meanwhile, PUDs exhibited excellent stability and polydispersity according to the above analysis. Tensile tests and dynamic mechanical analysis showed good mechanical and thermodynamic properties of PUD films. Some typical characteristics of crystalline polymers were revealed in the tensile stress–strain curves of PUD films. Peel strength test (PVC/PVC) yielded a maximum initial peel strength value of 6 N/mm and T-peel strength value of 10 N/mm. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The synthesis and characterization of electrical and magnetic nanocomposite: PEDOT/PSS–Fe3O4
Co-reporter:Dong Cheng Sun, De Sheng Sun
Materials Chemistry and Physics 2009 Volume 118(2–3) pp:288-292
Publication Date(Web):15 December 2009
DOI:10.1016/j.matchemphys.2009.07.060
The poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate)–Fe3O4 (PEDOT/PSS–Fe3O4) nanoparticles have been prepared by using polystyrene sulfonic sodium (NaPSS) as a dispersant and dopant. The characterization of nanocomposites was investigated by transmission electron microscope, X-ray diffraction, UV spectroscopy, electrochemical study, four-probe, thermogravimetric analysis and magnetic property measurement system. XRD revealed the presence of spinel phase of Fe3O4 and the average size was calculated to be about 12 nm. The conductivity of nanocomposites at room temperature is excellent and it depends on the Fe3O4 content. The thermal stability of composites is outstanding. Higher saturation magnetization of 6.47 emu g−1 (20 wt.% Fe3O4) was observed at 300 K.
Synthesis and characterization of high solid content aqueous polyurethane dispersion
Co-reporter:Qing-An Li;Dong-Cheng Sun
Journal of Applied Polymer Science 2007 Volume 105(Issue 5) pp:2516-2524
Publication Date(Web):11 MAY 2007
DOI:10.1002/app.24627

Aqueous polyurethane (APU) dispersions having a solid content of 50% were synthesized using dimethyol propionic acid (DMPA) as the stabilizing moiety. The principal diols used were poly-1,4-butylene adipate glycol (PBA). The diisocyanates used in this study were a 30:70 blend of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). All these samples were neutralized using triethylamine (TEA) and chain-extended using ethylene diamine (EDA). The effects of the COOH content, NCO/OH molar ratio, and molecular weight (Mn) of PBA on the properties of APU dispersion and its cast film were studied. Dynamic light scattering results revealed that these high solid content dispersions shown broad particle size distributions as well as bimodal. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA) results showed that as the hard segment content increased, the melting point (Tm) of the APU cast film increased, but the glass transition temperature (Tg) did not show significant alteration, when a PBA lower than 1000 Mn was used, the APU exhibited faint soft-segment crystallization and tended to form amorphous polymer. Tensile and T-peel strength tests attained excellent mechanical properties, such as a maximum Young's modulus of 166 MPa and the elongation at break reached to 2000%. T-peel strength test (PVC/PVC) yielded a maximum peel strength value of 8.8 N/mm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

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