The Preparation And Properties Of Waterborne Polyurethane/layered Double Hydroxides Composites

Waterborne polyurethane is a new polyurethane system in which water is used as the dispersion medium instead of organic solvents. Due to its non-toxic and non-combustible, environmental friendly and being easy to modify, Waterborne polyurethane has been widely used in such applications as coatings, adhesives, leather, foams and so on. The comprehensive performance of WPU, however, has a certain gap with SPU. To composite with inorganic nanomaterials is the hot research orientation. Layered double hydroxides(LDHs) are typical layered-structure anionic clays, which has been widely used as polymer filler in polyimide, PVC, EVA, nylon etc. It can effectively improve the mechanical performance, water resistance or even give polymer antibacterial and mouldproof performance when introducing antibacterial micromolecules into the interlayer of LDHs.(1) Novel waterborne polyurethane(WPU) composites based on Ni Al-LDH and Zn O were successfully synthesized by in-situ polymerization. The nanostructured Ni Al-LDH/Zn O was first grafted by isophorone diisocyanate(IPDI), forming the Ni Al-LDH/Zn O-NCO complex with-NCO group on the surface, which promotes its homogeneous dispersion in WPU matrix. The microstructure and particle distribution of the composites were characterized. The mechanical properties and the water resistance of the composites were improved. Furthermore, the composites also exhibit significant antibacterial activity towards G(_) Escherichia coli and G(+) Staphylococcus aureus.(2) LDHs can be used to control the sustained release of drug. Inspired by that we use p-hydroxybenzoic anionic(p-Bz OH) intercalated LDHs as filler to modify WPU. CO32-type Mg Al-LDH was firstly synthesized via HMT hydrolysis method and then transfered to p-Bz OH type Mg Al-LDH by ion exchange. The nanostructured Mg Al-(p-Bz OH)-LDH was then grafted by isophorone diisocyanate(IPDI), forming the Mg Al-(p-Bz OH)-LDH-NCO complex with-NCO group on the surface, which promotes its homogeneous dispersion in WPU matrix through chemical bond connection. The microstructure and particle distribution of the composites were characterized by SEM. The mechanical properties and the water resistance of the composites were improved when the Mg Al-(p-Bz OH)-LDH loading level is suitable. Furthermore, the composites can slowly release p-hydroxybenzoic anionic into the surrounding environment, and thus exhibit significant antibacterial activity towards G(_) Escherichia coli and G(+) Staphylococcus aureus.