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... preparation of anionic WPUDs dispersion from castor oil was shown in Fig. 1. Castor oil, IPDI, and DMPA were mixed into a dried double-neck flask and stirred (220-250 r/min) at 78 C for 10 min to obtain a homogenized mixture. Then several drops of DBTDL were added into the mixture as catalyst. When the mixture almost could not flow, MEK was added to reduce the viscosity of the pre-polymer. After reaction for ...
Citations
... Therefore, the addition of a certain amount of A172 can enhance the surface hydrophobicity of coatings to a certain extent. In the last decade, there are few studies on enhancing the hydrophobicity of polyurethane with silicon modification, and some data on hydrophobicity studies of polyurethane in the last decade at home and abroad were briefly listed in Figure 9 [12,18,20,25,30,31,[42][43][44][45][46][47][48][49][50][51][52][53][54][55]. ...
... Therefore, the addition of a certain amount of A172 can enhance the surface hydrophobicity of coatings to a certain extent. In the last decade, there are few studies on enhancing the hydrophobicity of polyurethane with silicon modification, and some data on hydrophobicity studies of polyurethane in the last decade at home and abroad were briefly listed in Figure 9 [12,18,20,25,30,31,[42][43][44][45][46][47][48][49][50][51][52][53][54][55]. It can be found from Figure 9 that the optimal addition amounts of silicon for each system varied from one research work to another because of the different original formulation and the type of silicon modification. ...
Waterborne coatings have obtained more and more attention from researchers with increasing concerns in environmental protection, and have the advantages of being green, environmentally friendly and safe. However, the introduction of hydrophilic groups leads to lower hydrophobicity and it is difficult to meet the requirements of complex application environments. Herein, we proposed an optimization approach of waterborne polyurethane (WPU) with vinyl tris(β-methoxyethoxy) silane (A172), and it was found that the surface roughness, mechanical properties, thermal stability and water resistance of WPU will be increased to a certain extent with the addition of A172. Moreover, the hydrophobicity of the coating film is best when the silicon content is 10% of the acrylic monomer mass and the water contact angle reaches 100°, which could exceed two-thirds of the research results in the last decade. Therefore, our study can provide some theoretical basis for the research of hydrophobic polyurethane coatings.
In this work, a self-emulsifying CO2-based polyol (LAPEC) was prepared by the terpolymerization of propylene oxide, allyl glycidyl ether and CO2, followed by thiol-ene click reaction with mercaptopropionic acid. And the carboxyl group was successfully introduced into LAPEC verified in ¹H NMR. LAPEC was served as both soft segments and internal emulsifiers for WPU. Meanwhile, γ-aminopropylmethyldiethoxysilane (KH902) was also employed to improve the mechanical properties of WPU. Compared to dimethylol propionic acid (DMPA), WPU emulsion prepared by LAPEC had smaller particle size and higher emulsification efficiency. And the performance differences between LAPEC-based WPU films (LWPUs) and DMPA-based WPU films (DWPUs) with different hard segment contents were studied. The stronger hydrogen-bonding interactions improved the tensile strength, toughness and thermal stability. Compared with DWPU, the tensile strength and the elongation at break of LWPU respectively increased from 17.8 to 21.1 MPa and from 302.3 % to 356.5 %, when their hard segment content was both maintained around 37 wt%. Meanwhile, due to rougher surfaces and more hydrophobic silicon clusters, LWPU had stronger surface hydrophobicity. Therefore, LAPEC can provide a new way to synthesize WPU with high toughness and can be potentially used for flexible substrate coatings in the future.
Covalent crosslinking can improve the water resistance of waterborne polyurethanes (WPUs), but the preparation time of WPUs will be greatly extended by the crosslinking process, and the long-term storage stability of WPU emulsions will decrease because the crosslinked molecular chains cannot disperse in any organic solvents or water. In this paper, a crosslinked WPU was prepared through a post metal-organic crosslinking toward a conventional linear WPU. This post crosslinking is quite fast since it is based on the ionic bond interaction between metal cations and organic anions. The crosslinked WPU emulsion has narrow particle size distribution and small average size, giving rise to excellent long-term storage stability. Additionally, the water absorptions of the crosslinked WPU at 25°C and 60°C are 6.3% and 8.6% respectively, which decrease by 47.9% and 39.4% compared with those of the linear counterpart, indicating that the post metal-organic crosslinking highly improves the water resistance of the WPU. The mechanical strength of the crosslinked WPU also improves compared with the linear WPU.
