Rapid Fabrication of Novel Superhydrophobic/Superoleophobic Fluorosilicone Materials and Their Application

Author:Zhang Hao

Supervisor:zhang qiu yu


Degree Year:2018





Inspired by dewetting behavior from nature,superhydrophobic/superoleophobic surface(CA>150°,SA<10°)as such a special wetting performance enables it valuable in the application of self-cleaning.Up to date,lots of methods have been presented to fabricate superhydrophobic/superoleophobic surfaces,but there are still some problems existing.At first,low surface tension resulting from fluoropolymer reduces the mechanical durability of superhydrophobic/superoleophobic surface.Because of the molecular weak interactions,the binding between fluoropolymer and substrate is poor.Fabrication is also tedious.Designing new fluoropolymers can be an effective way to resolve these issues,but seem to be standing still in designing such hydrophobic polymers.Besides,poor mechanical life has turned into the bottleneck for large-scale industrial applications of the superamphiphobic surfaces.And the critical protocol that consists of low surface energy,multiscale roughness and overhanging curvature,following Cassie-Baxter models,is still a challenge to retain when subjected to damage.To solve these problem,many attempts have been made to attain durable superoleophobic coatings,including crosslinking the coating layer,creating multi-scaled roughness on the substrate,generating chemical bonds between coating and substrate,introducing a bio-inspired self-healing function.But a single approach can’t meet the requirement of durability in the application.Lots of defects such as in the interface of micro/nano composite structure and the reduction in the efficiency of self-healing have been still unsolved.To fix these issues above,we followed wetting theory and fabricated durable superhydrophobic/superoleophobic sufaces using a multimethod.Influences of composition and micro/nano-structure on wetting performance,mechanical/chemical stability and anti-smudge behavior were illustrated.And the mechanisms of interface stability and self-healing were also put forward.The surface has some potential to be used in some areas including self-cleaning,oil-water sepearation,drag-reduction,anti-icing as well as fast-developing microfluidics,batteries,and sensors.The content is listed as follows:(1)A novel branched T-FAS including T-FAS6(-C6F13)and T-FAS8(-C8F17),with low fluorinated surface energy and high sol-gel reactivity,was designed and synthesized via a rapid and effective thiol-ene click chemistry.Herein,the branched T-FAS serves as a key component that employs an average of two hydrolysable silane chains as the body and long fluoroalkyl chains.It not only offers lasting low surface energy even if the coating was damaged,but also has a lasting reaction because of a high crosslinking durable Si-O-Si network via the hydrolysis of-Si(OCH3)3 groups and an adhesion to the substrate,which is well applied to the hydrophobization of fibers.(2)Based on the stability enhancement theory,we prepared durable T-FAS6/PDMS/H-SiO2self-healing superhydrophobic coating by introducing elastic interpenetrating networks.The hybrid coating has a water contact angle of 165°and shedding angle of 4°,but wetting to peanut oil.It shows can withstand at least 100 cycles of abrasion with 1 500 grit sandpaper under 45kPa due to self-reinforced effect produced through the interpenetrating polymer networks(IPN)of T-FAS6/PDMS.The IPN is also self-healing to chemically etching so that WCA recover from103°to 160°.High stabilities to strong acid,UV,thermal and smudge treatment are observed.(3)To extend dewetting performance and self-healing efficiency,we designed T-FAS6/FOTS self-healing superhydrophobic network on the etched fiber by introducing high-crosslinking strategy.The superhydrophobic structure parameter is obtained by a rapid soda-decating method on the PET fiber.Compared by T-FAS6/PDMS/H-SiO2,the coating shows an oleophobic behavior the first time and has a CA of 148°,SA of 19°to peanut oil.The coated fabric was highly durable to withstand at least 1000 cycles of abrasion under 45 kPa and resistant to strong acid/base(e.g.,H2SO4,KOH),UV,thermal,and smudge treatments due to Si-O-Si network and-(CF2)5CF3 dangling chains.Moreover,regardless of severe physical or chemical damage,the coating rapidly restored its super liquid repellent properties.The self-healing time reduces from 1 h at 150℃to 10 min at 135℃.(4)Furthermore,based on the structure induced by etching,we introduced a long-chain T-FAS8 flurosilicion and CVD strategy.A low maintenance superamphiphobic T-FAS8@FOTS coating based on a smart two-layer self-healing network has been presented in its true sense.On the one hand,the coated fabric induced by the upper FOTS layer of coating has CA of 168°,162°and 155°and SA of 4°,5°and 8°to water,ethylene glycol and peanut oil,respectively.On the other hand,the coated fabric induced by T-FAS8 inside can withstand at least 200 cycles of abrasion under a pressure of 45 kPa without apparently changing the superamphiphobicity.Surprisingly,all the drops were still located on the broken coatings and no wetting/pollution was observed when the fabrics were suffered from serious damages including finger-wipe,sandpaper abrasion(80 mesh)and knife-scratch.Besides physical and chemical damages,the coating can even rapidly retain its super liquid-repellence against a long-term accumulation of smudge.Compared by T-FAS6/FOTS network,it shows strongly resist to UV radiation,boiling treatment,strong acid/base immersion and smudge treatment due to the barrier of C8 long fluoro chains.(5)A liquid-repellent“glue+particles”approach has presented an excellent idea for promoting the stability of superamiphiphobic surfaces.The self-healing F-SiO2@T-FAS8@FOTS superamphiphobic network was introduced.The coating based on a sol-gel network showed exceptional liquid-repellency to low surface tension liquids including ethanol with surface tension of 22 mN·m-1(CA=147°).The durability of coatings can be greatly improved by these strategies above.The robustness of superamphiphobic fabric reaches an optimum value.The water and oil drolepts remain sphere even after 1 000 cycles of abrasion against the pristine substrate(WCA>150°,OCA>120°).The coating has a better comprehensive and rapid self-healing behavior which can rapidly restore the superamphiphobictiy to severe etching,abrasion and even AO damage under the protection of the Si-O-Si network of SiO2 nanoparticles.Its liquid wettability for ethanol could be restored to 142°.Besides,it can repel hot liquids being as a rigorous method to evaluate the thermostability.The OCA was still above 145°and almost reached a superoleophobic region after an oil contamination and clean treatment.And the stabilities to acid and base achieve the optimal.The CAs and SAs to water and peanut oil only reduce to 158°,129°and 17°,59°.(6)A rapid and lasting self-healing from the reorientation of fluorochains was put forward.The T-FAS dangling long fluorochains introduced by a thiol-ene click chemistry forms a both branched and durable network.Compared by the self-healing from free molecules,the self-healing from the T-FAS branced network is rapid and lasting.Finally,through a series of design and optimization,the elapsed time for self-healing reduces from 1 h at 150℃to 10 min at 135℃and the way extends from base etching to abrasion,pollution and AO damage.Besides,the self-healing exhibits excellent stability after seveal cycles without apparent loss(η>80%).The usage life of the coatings is well extended.