Jianquan Tan

Waterborne UV-curable comb-shaped (meth)acrylate graft copolymer containing long fluorinated and/or polysiloxane side chains

A series of waterborne UV-curable comb-shaped (meth)acrylate graft copolymers containing long fluorinated and/or siloxane side chains were synthesized by conventional radical copolymerization of a novel mono-methacryloyloxy terminated fluorinated macromonomer (PHFA-GMA) and/or polysiloxane macromonomer (SiOHMAC) with (meth)acrylate monomers. The separate effects of PHFA-GMA and SiOHMAC, as well as the synergic effect of these two components, on the properties, especially the surface properties were investigated in detail. A hydrophobic surface could be obtained with extremely low content of PHFA-GMA and/or SiOHMAC due to the strong tendency of the macromonomers to migrate towards the outmost layer, resulting in abundant enrichment of fluorine and silicon atoms on the surface. XPS (X-ray photoelectron spectroscopy) results revealed that for a given weight of the two macromonomers, Si atomic concentration of the copolymer modified by SiOHMAC is higher than F atomic concentration of the copolymer modified by PHFA-GMA. AFM (atomic force microscopy) images showed that surface of the copolymer modified by SiOHMAC is rougher than that modified by PHFA-GMA. Compared to PHFA-GMA, SiOHMAC had higher efficiency and effectiveness in creating hydrophobic surfaces. In addition, the influence of PHFA-GMA and/or SiOHMAC on the physical properties, such as water dispersion particle size, water absorption, pencil hardness, adhesion, mechanical properties and thermal properties were also investigated. The novel comb-shaped copolymers prepared via conventional radical polymerization not only had excellent properties but also have potential applications in large scale industrialization.

Synthesis and characterization of UV-curable acrylate films modified by functional methacrylate terminated polysiloxane hybrid oligomers

A series of novel methacrylate terminated polysiloxane hybrid oligomers and functional acrylate oligomers were synthesized and characterized by GPC, FT-IR and NMR. The functional polysiloxane oligomers were introduced into the acrylate UV-curing system to improve its surface and thermal properties. With increasing the organosiloxane content, the contact angles of the UV-cured films increased, suggesting that the organosiloxane segments migrated to the top surface. The SEM and EDS results demonstrated the migration of the organosiloxane segments. The refractive index results showed that the optical performance did not decrease after the organosiloxane segments were incorporated. According the TGA curves, the decomposition temperatures of the polysiloxane/acrylate composite UV-cured films were higher than that of the pure acrylate UV-cured film, which demonstrated that the organosiloxane groups enhanced the thermal properties of the acrylate film due to the high energy of the Si–C bond. The observation of the fractured-surface morphology showed that the organosiloxane segments floated on the surface of the UV-cured films.

Nano- and micro-structured random copolymer modified cycloaliphatic epoxy resins for use as light-emitting diode encapsulation

ABSTRACT Poly(2,2,3,4,4,4-Hexafluorobutylmethacrylate–random–glycidolmethacrylate) random copolymer (P(HFBMA-r-GMA)) was synthesized via free radical polymerization. The novel reactive random copolymer was incorporated to modify cycloaliphatic epoxy resins and obtain the nano- or micro- structured composites. The chemical structures of P(HFBMA-r-GMA) were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The morphology and light transmittance of the cured epoxy resins were observed by scanning electron microscopy (SEM), transmission electron microscope (TEM) and ultraviolet-visible spectrophotometry (UV-vis), respectively. It is indicated that the optical transmittance of composites were basically kept although the microphase separation occurred in the curing process, which has a profound influence on the mechanical properties and refractive indexes. The thermal properties, surface dewettability and water absorbency of the cured epoxy resins were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle measurement and immersion test respectively. The experimental results revealed that the values of glass transition temperatures (Tg), surface dewettability and water resistance were effectively improved by the high cross-linking density and the enrichment of the fluorinated random copolymer dispersing in the composites. With respect to the corresponding properties of the neat epoxy resin, P (HFBMA-r-GMA)-0.25 hybrimer embraced the relatively good comprehensive properties, making the modified epoxy resins as good candidates for LED encapsulation.

Synthesis and properties of fluorine-containing polyurethane based on long chain fluorinated polyacrylate

Abstract For the first time, a novel fluorine-containing polyurethane (FPU) was prepared by introducing long chain fluorinated polyacrylate into PU. The FPU was prepared from dodecafluoroheptyl methacrylate (DFMA), β-mercaptoethanol (β-ME), methacryloyloxyethyl isocyanate(MOI), hydroxyethyl methylacrylate (HEMA), iso-butyl acrylate(I-BA), polyether diol (N220) and toluene diisocyanate (TDI). The structure of product for every step was confirmed by Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (1H-NMR) spectra. It was found that when the DFMA content increased from 0 to 12%, thermal stability was improved in some degree; the hardness, the adhesion and the tensile strength increased; the swelling degree in water, NaOH solution and HCl solution decreased; the solvent resistance in hexane and butanone improved to some degree; the contact angle of water and ethylene glycol increased; the surface free energy decreased. XPS tests indicated fluorine migrated to surface.

Synthesis and Characterization of Novel UV-curable Fluorinated Polyurethane-acrylate Copolymer

A series of UV-curable fluorinated polyurethane-acrylate(PUA) has been developed by incorporating octafluoropentyl alcohol into the segment of UV-curable polyurethane-acrylate to improve the thermal property and surface property of the copolymer material. The structures of the synthesized polymers were characterized by Fourier transform infrared(FTIR) spectrometry. In order to find out the effect of incorporated fluorine on the UV-cured films, the properties of the UV-cured films were tested through contact angle, water absorption, and thermogravimetric analysis (TGA). The fractured-surface morphologies of the UV-cured coatings were investigated by scanning electron microscopy(SEM). With increasing the content of fluorine segments, the contact angle of the UV-cured films increased and the water absorption decreased, suggesting the fluorine segments migrated and formed a fluorine-covered surface to avoid water penetration. The observation of the fractured-surface morphology through SEM test showed that the fluorinated UV-cured films gained rough fractured-surface compared with the pure UV-cured polyacrylate film, demonstrating the migrating of the fluorine segments. The TGA curves show that the fluorinated UV-cured films gained higher thermal degradation temperature than the virgin UV-cured polyacrylate film. And as increasing the fluorine content, the thermal degradation temperature increased. These phenomena could be reasonably explained by the enrichment of fluorinecontained segment on the surface of the film and the high thermal property due to fluorine atom.

Preparation and self-assembly of pH-sensitive amphiphilic comb-shaped copolymer containing long fluorinated side chains

ABSTRACT Novel pH-sensitive amphiphilic comb-shaped copolymers containing long fluorinated side chains, which combined the characteristics of pH-sensitivity from pendent tertiary amine groups, unique hydrophobic and fluorophobic characteristic from the fluorinated moieties and hydrophilicity from the poly (ethylene glycol) segments, were designed and synthesized via radical polymerizaion of 2-(Dimethylamino) ethyl methacrylate (DMAEMA), poly (ethylene glycol) methyl ether methacrylate (PEGMA) and homemade fluorinated macromonomer (PHFBMA-GMA). The physicochemical properties of polymeric micelles prepared therefrom were investigated. The chemical structures of the copolymers were characterized by GPC, FTIR and 1H-NMR. The critical micelle concentrations (CMC) of the copolymers in different pH (5.0 and 7.4) were determined by fluorescence spectroscopy. Larger CMCs could be obtained in lower pH since the pronation of DMAEMA moieties enhanced the hydrophilicity. With increasing the amount, as well as the molecular weight, of PHFBMA-GMA, CMC decreased significantly. As pH decreased, particle size, as well as zeta potential of the polymeric micelles increased significantly, indicating significant pH-sensitivity of the polymeric micelles. Furthermore, larger polymeric micelles were obtained with larger amount, as well as higher molecular weight, of PHFBMA-GMA. Transmission electron microscopy (TEM) showed that the morphological shapes of the copolymers performed spherical micelles. The cytotoxicity test showed that the comb-shaped copolymers performed extremely low cytotoxicity. The pH-sensitive polymeric micelles prepared from the amphiphilic comb-shaped copolymers containing long fluorinated side chains could be potential candidates for nanotanks for hydrophobic or fluorophobic molecules and drug carriers and the facile preparation might fit for large scale industrialization.