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Jul 31, 2023
The researchers used IPDI, PTMO, and siloxane diol as raw materials, and adopted a two-step synthesis method. First, IPDI and siloxane were prepolymerized, and then copolymerized with PTMO to modify polyurethane. The influence of siloxane structure on reaction speed and mechanical properties, the influence of siloxane functional group main chain series KF3200, KF5600 and side chain series X2500, X4900 on siloxane structure and the effect of molecular chain size on bulk reaction and solvent were studied. Influenced by the reaction rate, the properties of the polymeric materials were investigated, and it was found that the reaction speed of the X series was larger than that of the K series in the bulk reaction, and for the same series of reactive molecules, the larger molecules were slower than the smaller molecules, and the main chain silicon The hydrophobic shielding effect of oxane and the stereoscopic effect of branched siloxane are the reasons for this phenomenon. In the solvent reaction, because the shielding effect is greater than the stereoscopic effect, the molecular weight of the polymer modified by the branch chain is greater than that of the main chain modified.
In terms of mechanical properties, the main chain modification has a large elongation at break, while the branched chain modification has a higher tensile strength. Modified polyurethane was synthesized by using PDMS70-(0H)2, PDMS60-0H and PDMS20-COH as raw materials. The advancing angle A of the liquid on the solid surface, the receding angle U of the liquid surface, and The influence of contact angle hysteresis on CAH was studied, and it was found that the different hydrophilic and hydrophobic segments contained in the raw materials and the length of the chain had an impact on the modified 0A, 0R, and CAH.
PDMS20-(OH) is due to the fact that it contains a hydrophilic PEO moiety and leads to chain segment activation, which cannot prevent surface re-formation, leading to CAH and longitudinal decline, while the results of PDMS70-COH)2 and PDMS60-OH are the same, because the long chain prevents When the top branch enters in water, it is sensitive to low surface energy and relies more on high surface energy. Therefore, the higher the treatment temperature, the lower the temperature, and the faster the improvement speed of 0R than 0R. Using high-frequency linear silicone oil with valleys in the terminal to study the synthesized polyurethane prepolymer containing active-NCO groups in the terminal, it was found that when the content is rare, due to the strong surface migration ability of the silicone chain, a small amount of components migrate to the surface , so that the bulk properties of the material change obviously, while the surface properties change more obviously.