Synthesis And Application Of Hyperbranched Polyether And Hyperbranched Polyether Sulphone Epoxies

Epoxy resins are widely used as coating, electronic packaging and composite materials because of their excellent properties, including strong adhesion, low shrinkage, and excellent electrical properties, etc. However, the poor toughness and anti-corrosion performance of traditional epoxy limits its wider application. As a result, tremendous effort has been focused on toughness and anticorrosion improvement during past decades. Tougheners such as rubber, thermoplastic resin, nano-inorganic particles, and hyperbranched polymers have often been used in improving the toughness of epoxy. When rubber, thermoplastic resin, nano-inorganic particles, and hyperbranched polymers are blended with epoxy, improvements in toughness are often achieved at the expense of modulus, intermiscibility, viscosity, and glass transition temperature (Tg). Conducting polymer, inorganic nanoparticle, siloxane based polymer, polyurethane, etc. have often been used in improving the anticorrosive performences of epoxy coating, however, they can not address the poor coating compactness fundamentally. In this dissertation, a series of new epoxide terminated hyperbranched polyethers and hyperbranched polyether sulphones were synthesized and used as modifiers for linear epoxy resin to develop high performance epoxy material. Effects of main chain structure and molecular weight on various properties were systematically investigated, which is valuable for future application of hyperbracnhed polymers. The dissertation includes but not limit to the following contents:1. Based on proton transfer polymerization mechanism, a series of epoxide terminated hyperbranched polyethers (EHBPE) were designed and synthesized. Structure of EHBPE was confirmed by NMR and FTIR. Effects of main chain structure and molecular weight on melt rheological properties of EHBPE were systematically studied. Based on time-temperature superposition principle, master curves of EHBPEs were constructed. The terminal slopes of lgG" master curves are 1.0, whereas the lgG’master curves show unusual step changes, which has not been reported. When molecular weight and main chain rigidity increases, the step changes become more obvious, which can be related to changes in polarity interaction, high polydispersity (PDI), and high degree of branching (DB). The strong fluorescence of all aliphatic EHBPE1 was reported for the first time. Results indicated fluorescence mechanism of EHBPE 1 conforms with AIE.2. A high performance hybrid epoxy anticorrosive coating was prepared by incorpating EHBPE2 into linear epoxy. Effects of main chain structure and molecular weight on the anticorrosive performences of epoxy coating were measured. Results showed that EHBPE2 with benzene ring and aliphatic chain shows optimum anticorrosive performance. Compared with neat DGEBA coating, acid and salt fog resistance of hybrid epoxy coatings with 5% EHBPE loading show an increase of 550% and 320%. Electrochemical impedance spectroscopy (EIS), SEM, low field NMR (LF-NMR) and salt fog test analysis showed that addition of EHBPE2 can increase the crosslink density of coating, thus increase the anticorrosive performance.3. A series of novel hyperbranched polyether sulfone (HBPESs) were designed and synthesized. An epoxide terminated hyperbranched polyether sulphone (EHBPES) were obtained by terminal group modification of HBPES, which were then used as tougheners for linear epoxy. Effects of main chain structure and molecular weight on mechanical properties of epoxy materials were studied. Results showed that EHBPES3-2 with benzene ring, aliphatic chain, and medium molecular weight has optimum mechanical properties. EHBPES3-2 shows the optimal performance: impact strength, tensile strength, elongation at break and Tg of 5% DGEBA/EHBPES3-2 are 50.9 kJ/m2,80.0 MPa,15.3%, and 163℃, respectively. Compared with neat DGEBA, impact strength, tensile strength, elongation at break and Tg of 5% DGEBA/EHBPES3-2 show an increase of 76.7%,19.6%,74.9%, and 17℃, respectively. DMA, DSC TMA, and SEM analysis indicated that the improved toughness and strength of hybrid material can be related to increases in crosslinking density and free volume, as well as the special structure of hybrid network.4. A high mechanical performance copolymerized epoxy material was obtained by copolymerzing EHBPES3-2 with linear epoxy. Effects of EHBPES3-2 loading on mechanical properties of copolymerized epoxy were studied. Results show that the mechanical properties of copolymerized epoxy increase with EHBPES3-2 loading up to 5%, then decrease at higher loadings. Compared with neat homopolymerized epoxy, the impact strength, tensile strength, elongation at break, and Tg of copolymerized epoxy show an increase of 22.0%,12.0%,47.3%, and 3.8 ℃, respectively. The improved toughness of DGEBA/EHBPES3-2 copolymerized epoxy could be related to the semi-spherical structure of EHBPES3-2 and possible relaxations of flexible chain segments.