Preparation Of Novel Fluorinated Polyphosphazene Elastomer And Its Application As Hydrophobic Coating On Cotton Fabric

Polyphosphazenes are a class of new organic-inorganic polymeric materials whose molecular chain is alternately composed of phosphorus and nitrogen single-double bonds.They possess more excellent fire-retardant properties,thermal stability properties and insulating properties than traditional carbon chain polymers.Meanwhile,polyphosphazenes show various physicochemical properties due to their easily adjustable side groups.Fluorinated polyphosphazenes are widely used in the fields of oil resistant sealing products,biomedicine and functionalized coatings due to their excellent hydrophobic,oil-resistant,biocompatible and acid base corrosion resistance.To meet the needs of better practical production and application for fluorinated polyphosphazene elastomers,and achieve the balance of basic application properties such as hydrophobic oil resistance,low-temperature resistance as well as thermally stable properties of synthetic elastomers,the thesis focuses on the design and synthesis of a variety of fluorinated polyphosphazenes with different side groups,and then evaluate the mechanical properties,oil resistance and flame retardant properties of vulcanized rubber products.The balance optimization method and synthesis technique of structure to performance regulation were obtained.Further hydrophobically modify on cotton fabric are attempted by compositing synthesized novel fluorinated polyphosphazene（PTHOP-2）and inorganic nanoparticles as a sizing agent,obtaining modified cotton fabric with high hydrophobicity,durability and friction resistance.1.Aiming at preparing fluorinated polyphosphazene elastomers with high oil resistance,PTHOP with different ratios of-OCH（CF₃）₂side group were synthesized,and the mechanical properties of PTHOP after vulcanization first increase and then fall down with the increase of the amount of-OCH（CF₃）₂side group The vulcanized PTHOP rubbers exhibited tensile strength up to 9.0MPa with 101%elongation at break.The volume expansion rate of PTHOP is about 1%and the tensile strength has slightly increased after the oil resistance test in No.10 and 15 hydraulic oils at 150°C.The PTHOP-2 sample achieved the optimal oil resistance that the volume expansion rate of PTHOP-2 after oil immersion was only 0.38%,and the tensile strength was up to 10.3 MPa with100%elongation at break.Compared with PTOP elastomer,the introduction of-OCH（CF₃）₂group was able to obviously improve the oil resistance of the material.2.Fluorinated polyphosphazenes（PFMP）with different ratios of-OC₆H₄CF₃side groups were synthesized to develop novel fluorinated polyphosphazene.The-OC₆H₄CF₃group is able to enhance the thermal stability of the product,but also lead to a small increase in the glass transition temperature.The tensile strength of the vulcanized PFMP samples didn’t change with the variation of amount of-OC₆H₄CF₃groups,however,the elongation at break decreased with the amount of-OC₆H₄CF₃group.3.With the purpose of preparing modified cotton fabrics with high hydrophobic performance,a composite coating was constructed on the surface of cotton fabric by introducing inorganic nanoparticles and PTHOP;The hydrophobic performance of modified cotton fabric with composite of hydrophobic Si O₂and PTHOP was optimal,and the contact angle reached151.4°.Meanwhile,the modified cotton fabric exhibited excellent water-washing properties and good friction resistance which indicates that such materials have practical application value.