Study On Hydrophilic&hydrophobic Modification And Properties Of Polyethylene Surface

Wettability is defined as the ability of a liquid to maintain contact with a solid surface,which is determined by the adhesive force generated by the intermolecular interaction at the phase interface.In nature,wettability is a universal phenomenon from the microscopic to the macroscopic level.Polyethylene(PE)is widely used in industrial and technical fields,due to its excellent mechanical properties,friction resistance,chemical stability and easy processability.However,due to its non-polar chemical structure,it is difficult to introduce hydrophilic or hydrophobic groups on its surface,resulting in its lack of chromaticity,adhesion,hydrophilic or hydrophobic properties,which limits its further application in engineering and technology fields.Therefore,improving the surface wettability of polyethylene by simple methods has become a hot research topic in recent years.In this paper,hydrophilic and hydrophobic polyethylene materials were prepared by surface modification,respectively,glycidyl methacrylate(GMA)was used as a "bridge" to further introduce polyvinyl alcohol(PVA)containing a large number of hydrophilic groups on the inert surface of high-density polyethylene(HDPE)to prepare PVA@GMA-HDPE with good hydrophilicity and underwater super-oleophobicity.In addition,sodium fluoride(Na F)was etched on the HDPE surface to construct a micro-nanostructure rough surface,followed by the introduction of hydroxy fluorosilicone oil(HTFO)containing a large number of hydrophobic groups on the HDPE surface by chemical grafting.The HTFO@GMA-E/HDPE sheets prepared by the synergistic effect of the micro-nanostructure rough surface and the low surface energy surface not only exhibit excellent super-hydrophobicity,mechanical durability and chemical stability,but also have remarkable self-cleaning function and anti-icing performance.The details include the following.(1)In order to form a large number of reactive sites on the inert surface of HDPE,The GMA-HDPE was prepared by grafting GMA onto HDPE surface using solid phase grafting method.Fourier infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)analysis proved that GMA was successfully grafted on the HDPE surface.When the reaction time was 2 h,the reaction temperature was 105 ℃,the amount of initiator was 0.3 % of HDPE,and the amount of interfacial agent was 10 %of HDPE,the grafting rate calculated by mass method reached the highest value of2.36 %.(2)On the basis of GMA grafted HDPE,PVA was selected for hydrophilic modification of HDPE,and the surface structure of PVA@GMA-HDPE and the influencing factors of its hydrophilic modification were investigated.The addition of PVA improved the wettability of HDPE.When PVA was added at 13%,ring opener was added at 0.1%,and the reaction time was 2 h,the contact angle of PVA@GMA-HDPE in air was decreased from 93.52±2.3°to 23.33±3.1°and the contact angle of oil in water increased from 44.32±1.8°to 156.90±0.8°.With the significant improvement of the oil resistance,the grease on the PVA@GMA-HDPE surface can be easily removed even after several repeated washing with water.(3)The H@G-E/HDPE with superhydrophobic properties was produced by the synergistic effect of the rough surface of the micro-nanostructure and the low surface energy surface.The HDPE sheet was etched with saturated Na F solution to form a rough surface,and then GMA was introduced on the HDPE surface to form a large number of reactive sites on the inert surface of HDPE,and further grafted the low surface energy HTFO onto the HDPE surface.The H@G-E/HDPE sheet exhibited excellent hydrophobicity with a water contact angle(WCA)of 158±1° and a sliding hysteresis angle(SHA)of 8±1°.The hydrophobically modified sheets also exhibited good durability and chemical resistance,with WCA greater than 150° after 240 h of strong agitation in water or 120 times rubbing with sandpaper,and remained superhydrophobic after 24 h of immersion in strong acid/alkali solutions.In addition,the prepared H@G-E/HDPE sheets exhibited excellent dynamic wettability,maintaining super-hydrophobicity under water droplet impact at 0.77 m/s,as well as low ice adhesion at 11.64±1.74 KPa,long delayed icing time and self-cleaning properties.