Research And Application Of Slippery Organic Fluoro/Siloxane Materials

Adhesion-repellency is one of the centers of interface science and material engineering.A coating that can prevent the adhesion of various undesirable objects represents the most efficient and economical approach to address the adhesion issues.Liquid-infused surface(LIS)is emerging as the up-to-date generation of antifouling technology.In SLIPS,the liquid is stabilized on the surface to act as a solid from the viewpoint of the macroscopic level but maintains its mobility at the molecular level such that a smooth protecting liquid overlayer can form to allow various objects to slide away from the surface,rather than to adhere or absorb.In contrast to the superhydrophobic coatings,this class of slippery surfaces can suffer high pressure and are thus suitable for underwater applications,constituting one of the most promising strategies for marine antifouling.However,the current slippery coatings are generally expensive and show poor stability,hindering their practical applications.Moreover,this technology has not been applied in our country.This dissertation aims to address these issues by developing two kinds of cheap,self-replenishing slippery coatings that can be prepared by facile methods.The main findings and conclusions are as follows:(1)Perfluorogel is expected as the best slippery material.However,small molecule-based perfluorogels show poor mechanical properties,while polymer-based perfluorogel is extremely challenging to prepare and has not been constructed yet.To address this issue,a new approach to fabricating polymer-based supramolecular perfluorogel coatings is proposed in this dissertation.In this method,tapes(porous perfluoropolyether)are used.Immersing the tapes into perfluorinated lubricants like perfluoropolyethers will allow the lubricants to infuse the pores and swell the polytetrafluoroethylene(PTFE)matrices to get the gels.During the swelling,the lubricant molecules can diffuse into the low-crystalline PTFE domains but are shielded from high-crystalline regions that act as crosslinking interactions.These supramolecular perfluorogels exhibit stretching-controlling swelling ratios and outstanding ductility.They can also self-replenish the lubricant consumption on the surface by shrinking their network frameworks under external pressures.(2)Supramolecular perfluorogels still suffer the relatively high cost,poor elasticity,and low marine antifouling effect compared to silicone-based slippery materials.However,the silicone-based slippery elastomers currently available are mechanically weak and have pure hydrophobic nature,which hinders their applications in marine antifouling functions.This dissertation aims to address these issues by developing amphiphilic tough dynamic polydimethylsiloxane(dPDMS)elastomers with self-degradability.The elastomers are prepared by a new“two-in-one”approach in which the elastic materials were directly prepared via bulky anionic ring-opening polymerization(AROP)ofoctamethylcyclotetrasiloxane(D₄)with bis(tetramethylammonium)oligodimethylsiloxanediolate(BTMASA)as the initiator.The reaction results in the formation of dumbbell-type telechelic polymers with tetramethylammonium siloxanolate(TMASA)as the end groups.The telechelic polymers would self-assemble into networks associated with electrostatic interaction between TMASAs,leading to a structure with hydrophobic polydimethylsiloxane(PDMS)and hydrophilic TMASA domains.After polymerization,the TMASA maintains its activity and can trigger effective chain exchanges and a monomer-polymer equilibrium.Therefore,when the monomer,a ring-shaped small molecule lubricant,is consumed,the polymers would self-degrade to generate more lubricant molecules to maintain the surface slipperiness.Such dynamic substrates can swell silicone oil to form slippery surfaces with good antifouling properties.(3)Based on the preparation of these two types of inexpensive slippery materials,the applicability of these slippery materials for engineering applications and the effect of film-forming coating on drag reduction,wear resistance,and anti-biofouling are evaluated in application scenarios such as ships,large deep-sea breeding net box platforms,deep-sea breeding net suits,marine monitoring buoys,and large water diversion project ferries.It is fully demonstrated that the developed organic fluoro/siloxane slippery materials have good engineering applicability,obvious anti-fouling and drag-reducing effects,and show extensive application prospects.