Preparation And Modification Of Waterborne Hyperbranched Polyurethane

In the last decade, hyperbranched polymers have received intense interest due to their unique chemical and physical properties as well as their potential applications in coatings, modifers, polymer electrolytes, drug and gene delivery, nanotechnology. Highly branched polymers can be categorized as dendrimers and hyperbranched polymers. Dendrimers with perfect architecture are composed of dendritic and terminal units without linear units. By contrast, hyperbranched polymers are not well appreciated, lacking the perfection and beauty of architecture. Although hyperbranched polymers contain linear units as insufficient branching, many properties of dendrimers, such as good solubility, low viscosity and multi-functionality at end groups, are generally inherited. Since the early90s, a wide variety of hyperbranched polymers (HBP), such as polyphenylenes, polyesters, polyethers, polyamides, polycarbonates, and polyurethanes have been widely studied.Polyurethanes have been widely used for a number of important applications including foams, elastomers, coatings, and adhesives. The studies of hyperbranched polyurethanes (HBPUs) have become the focus not only due to the general advantages of hyperbranched polymers in common, but also the structure design of polyurethane chemistry with very special properties. Hyperbranched polyurethanes (HBPUs) bearing a large number of functional groups at their periphery could be used selectively for obtaining the desired properties according to the customers’ requirements. HBPUs have received much attention due to their unique chemical and physical properties as well as their potential applications.In the first chapter, we highlight the most representative synthesizing methods and applications for HBPUs in recent years. HBPUs can be prepared by means of single-monomer methodology (SMM) and double-monomer methodology (DMM). The intermediate monomers of SMM can be obtained through phosgene route, rearrange of carbonyl azide, high selective reaction, Curtius reaction and ketalization. DMM consists of A2+Bn approaches and A2+bB2approaches. Further more, a novel hyperbranched polymer methodology based on the chain extender reactions of hydroxyl-terminated hyperbranched polymer and isocyanate-terminated linear polyurethane prepolymer has been developed. The novel physical properties of hyperbranched macromolecules render them ideal candidates for use as shape memory materials, the base for various coating resins, solid polymer electrolyte, novel solid-solid phase change material for thermal energy storage, and so on. Meanwhile, we introduce the modifications of waterborne polyurethane. At last, the prospects of waterborne hyperbranched polyurethane are described.In the second chapter, we introduce degree of branching (DB), which is a comprehensive concept of hyperbranched polymer, and13C-NMR Analysis based on model compunds, a measurement method of DB. Frey proposed a new equation to calculate DB value and escape terminal units’influences. This equation is more accurate than define equation when DPn of polymer is low, and equivalent to define equation when DPn of polymer up to some extent.In the third chapter, the precursor of hydroxyl-terminated hyperbranched polyurethane (HBPU) was prepared from isophorone diisocyanate (IPDI), dimethylol propionic acid (DMPA) and diethanol amine (DEOA) via A2+bB2approach, and linear polyurethane (LPU) prepolymer was obtain by reacting IPDI, polytetramethylene glycol (PTMG) and DMPA. The aqueous dispersions were obtained based on the chain extension reactions of HBPU and isocyanate-terminated LPU. The structures of the HBPU and WPUs were proved by Fourier transform infrared (FT-IR) spectroscopy; the properties of cast film were measured by water resistance tests, tensile tests and thermal gravimetric analysis (TGA). The cast film of the resulting product (HBPU-6) exhibits good comprehensive properties:better water resistance, tensile strength, and thermal stability.In the fourth chapter, the precursor of hyperbranched poly(ester-amine)(HPAE) was prepared from ethyl acrylate and diethanol amine (DEOA) via A2+bB2method, and linear polyurethane was prepared from IPDI, DMPA and polytetrahydrofuran glycol (PTMG). Linear polyurethane was grafted onto HPAE, and then a stable aqueous polyurethane dispersion was obtained. The structures of the result polymer were characterized by FT-IR; the properties of cast film were measured by TGA, tensile tests and water resistance tests. The degradation temperature of the resulting product is265℃.In the fifth chapter, waterborne hyperbranched polyurethane was modified by acrylate based on HBPU-6. The mixture of polyacrylate and hyperbranched polyurethane (HBPU/PA) and copolymer of polyacrlate and hyperbranched polyurethane (HBPUA) were prepared, and they got core-shell structure confirmed by TEM photograph. Compare to HBPU/PA, HBPUA performance better tensile strength, but lower enlongation precent at break.