Preparation And Performance Of Waterborne Polyurethane Modified By Novel Fluorine-containing Alcohols

In recent years,due to the social advocacy of green-development,waterborne polyurethane(WPU)has gradually become a research hotspot as leather coating film-forming materials.However,there are many hydrophilic groups in the WPU molecular chain,resulting in poor hydrophobic properties of the film,which then goes against its application performance.Studies have shown that the fluorine-containing carbon chain in organic fluorine compounds has a strong shielding effect and stability,can reduce the surface energy of the material.Therefore,organic fluorine compounds are frequently an ideal candidate to improve the hydrophobic properties of WPU films in many research works.Based on the excellent properties of organic fluorine compounds,the triazine-based fluorinated diol and the branched fluorinated monoalcohol were synthesized through molecular structure design,and were used to modify WPU to effectively improve the hydrophobicity of the film in different systems,respectively.The specific work is as follows:(1)Preparation and properties of triazine-based fluorinated diol modified waterborne polyurethane(CC-FPUF)Firstly,triazine-based fluorinated diol(CC-F)was synthesized by the reaction of cyanuric chloride(CC),octa-fluoro pentanol(OFP),and ethanolamine(MEA).Secondly,isophorone diisocyanate(IPDI)and polybutylene adipate(CMA-1044),CC-F and dimethylolpropionic acid(DMPA)were reacted to prepare a polyurethane prepolymer with-NCO groups as the end tails of the molecular chain.Then,perfluorohexyl ethanol(S104)and trimethylolpropane(TMP)were used to react with the-NCO at both ends of the prepolymer.And finally,CC-FPUF was obtained by neutralization and emulsification.After that,the influence of the CC-F content on the size and morphology of CC-FPUF latex particles,the thermal properties,the molecular arrangement,the surface elements and morphology,hydrophobicity,and mechanical properties of the CC-FPUF films were also explored in detail.FTIR and NMR proved that the molecular structures of CC-F and CC-FPUF conformed to the previous design.TEM and DLS showed that the latex particles of CC-FPUF were spherical,and the size of the latex particles increased with the increase of the CC-F content.TGA and DSC revealed that the thermal stability of the CC-FPUF films was gradually improved because of the addition of CC-F.With the increase of CC-F,XRD found that the CC-FPUF films were mainly amorphous,although some crystallization formed.XPS proved that more fluorocarbon segments migrated to the films surface,resulting in a gradual increase of the fluorine content on the surface.And the flatness of the surface and section of films decreased in SEM observation while the degree of microphase separation and roughness of films gradually increased in the AFM images.When the content of CC-F reached 8%(CC-FPUF-8)in CC-FPUF,the degree of microphase separation of the film was the largest,and the WCA was 125.8°,which is an increase of 34.1° than CC-FPUF-0 film.The tensile strength and the elongation at break of CC-FPUF-8 film were 36.63 Mpa and 557.09%,resepectively.In short,CC-FPUF-8 film showed excellent hydrophobic properties and good mechanical properties.(2)Preparation and properties of branched fluorinated monoalcohol modified waterborne polyurethane(PUBF-1/2/3)First,perfluoro-1-butanesulfonylfluoride(PBF)was used to react with trimethylolpropane(TMP)and pentaerythritol(PE)to prepare branched fluorine-containing monoalcohol with two and three fluorocarbon segments(BF-2 and BF-3),respectively,and the monoalcohol with a fluorocarbon segment(octa-fluoro pentanol,denoted as BF-1)used as a control.Next,a polyurethane prepolymer with-NCO groups as the terminal group of the molecular chain was synthesized by using IPDI and CMA-1044 as raw materials,and DMPA as a chain extender.Then,the prepolymer was capped one side by BF-1,BF-2,and BF-3,respectively,and the other side was cross-linked by TMP.Finally,PUBF-1,PUBF-2,and PUBF-3 was obtained by neutralization and emulsification.After that,the difference in the size and morphology of latex particles,the thermal properties,the molecular arrangement,the surface elements and morphology,hydrophobicity,and mechanical properties of film between PUBF-1,PUBF-2,and PUBF-3 was also explored.FTIR and NMR proved that the molecular structures of products conformed to the previous design.TEM and DLS showed that the latex particles of PUBF-1,PUBF-2,and PUBF-3 were spherical,and the size of the latex particles gradually increased.TGA and DSC revealed that the thermal stability of the corresponding film had improved.XRD found that PUBF-1,PUBF-2,and PUBF-3 films were mainly amorphous,while some microcrystals formed in PUBF-3.XPS proved that more fluorocarbon segments migrated to the surface of films,resulting in gradual increase of the fluorine content on the surface of PUBF-1,PUBF-2,and PUBF-3 films.And the flatness of the surface and section of the corresponding film decreased in the SEM,while the degree of microphase separation and the roughness of the films gradually become bigger in the AFM images.As a result,the WCA of PUBF-1,PUBF-2,and PUBF-3 films were 77.8°,91.5°,and 106.4°,respectively,indicating that the hydrophobic properties of the films had been effectively improved.Besides,the mechanical properties of the films had also been improved.