Synthesis, Characterization And Application Of Waterborne Hyperbranched Polyurethane

Hyperbranched polymer(HBP) is one of the hot research spots in the polymer material fields in recent years. It has attracted much attention because of its special hyperbranched structure, its large amount of terminal groups and the properties of low viscosity, non chain entanglement, good solubility etc. which come of the special structure in comparison with their linear analogues. HBP has very good potential prospects in nano material, luminescent materials, coatings and many other fields. In recent years, people study HPU not only in the mothod of synthesis, physical and chemical characteristics, but also the research of its molecular theory, various functionality, preliminarily attempt on application and so on.Hyperbranched polyurethane(HPU) material has been paid much attention by the polymer materials scientists for its two characteristics of HBP structure and nice properties of polyurethane. Although there have been many reports about the synthesis of HPU, the studies of water borne hyperbranched polyurethane(HWPU) are few, and the studies of different generation products of HWPU haven't been reported. The synthesis of new HWPU and the study for its structure and application are innovative research work. This work is useful for people to recognize the sturcture and properties of HBP, and has the value both in academic study and in practical application. Besides, this research is very helpful to prepare water-borne polymer material, to push the application of environment-friendly material and to develop the low-carbon economy.The method of coupled monomers was used to synthesize a series of novel HWPU and new different generation HWPU products, the HWPU synthesized was tested and characterized, the relationship between structure and properties of HWPU was studied, and the potential applications of HWPU was discussed.The reactive intermediates of A₂ type was prepared by the reaction of toluene-2, 4-diisocyanate(TDI), or Isophorone diisocyanate(IPDI) with dimethylolpropionic acid (DMPA), and the diethanolamine (DEA) was the monomer of B₂B* type. Through the reaction method of coupled monomers of A₂+B₂B*, the reactive intermediates of AB₂ type was synthesized. Then the aromatic HWPU and aliphatic HWPU could be synthesized by condensation polymerization of AB₂ type reactive intermediates. Core HWPU was synthesized by AB₂ type reactive intermediates (as for raw material) and melamine (as for core molecule). With the similar mothod, the PPG HWPU was synthesized by the raw material of TDI, 400 molecular weight polypropylene glycol (PPG-400), DMPA and DEA. The whole reaction course was monitored by measuring the NCO value. Through matching the theoretical NCO value and the measured actual NCO value, the different generation HWPU products were synthesized by terminating the reaction properly in the aromatic HWPU reaction. In the synthesis reaction above, white powder products could be got by washing, drying the products. The yield could reach about 90% and the products are soluble in H₂O after alkali neutralization.The acid value of reaction system was monitored by chemical analysis in the reaction of HWPU synthesis, and the determination results indicated that the–COOH group didn't participate the reaction basically.The research of viscosity indicated that the whole series of HWPU have a special viscosity which is different from that of linear polymer. The viscosity of HWPU products can increase with the rise of molecular weight generally, but there is a stage which the vicosity dicrease at first and then increase again in the rise process of the viscosity.The reaction process was monitored by FTIR spectroscopy, the products were tested by NMR spectroscopy. In comparison with the model compounds which were synthesized first, the hyperbranched polyurethane structure of HWPU was proved. The degree of branching (DB) of HWPU was more than 0.8, the HWPU molecular weight determined by GPC was more than 1.0×10⁴.In comparison with LWPU which had the similar chamical composition with HWPU, it was found that LWPU and HWPU had different thermal degradation process. In first thermal degradation stage, LWPU and HWPU occurred thermal degradation at about 190℃, but HWPU had a second thermal degradation stage in higher temperature (at about 270℃). The increase of HWPU molecular weight had amost no effect on thermal degradation process. The results of TG-FTIR analysis proved the thermal degradation process of HWPU. The temperature of glass (T_g) analysis by DSC indicated that the T_g of HWPU could reach 130-140℃, and the T_g of HWPU was much higher than that of LWPU (about 105℃). The T_g of HWPU could rise with the increase of HWPU molecular weight.In comparison with the coating of pure LWPU and the mixed coating of LWPU and HWPU, the adding of HWPU could increase the gloss and the hardness of the pure LWPU coating obviously, and the PPG-400 could increase the flexibility and the impact resistance of the pure LWPU coating.