| Separation membranes as an important branch of membrane materials have demonstratedimportant value in daily life and industrial production.Polymer separation membranes have attracted the attention of researchers because of their simple preparation methods,low-energy treatment processes,and high separation efficiency.This thesis mainly studies the preparation of multifunctional polymer films by the method of initiated chemical vapor deposition?iCVD?and their applications in separation membranes.The influences of film materials with different compositions on the adhesion between film and substrate,film stability,and surface functionality of the film were explored.Hydrophilic surfaces were prepared and their applications were studied.Specifically as follows:1.Layered polymer thin films were successfully synthesized and deposited on wool andPVDF membrane through a one-step iCVD process.The film is consisted of polyisocyanate ethyl methacrylate?PIEM?primer,a crosslinked poly?isocyanate ethyl methacrylate-co-2-hydroxyethyl methacrylate?(P?IEM-co-HEMA?layer,and grafted?poly-2-hydroxyethyl methacrylate??PHEMA?.PIEM contains a very active functional group–NCO,which can be harnessed to improve the adhesion between film and substrate through the interface chemical reaction.The coated wool and PVDF membrane both achieve superhydrophilicity and underwater superoleophobicity.The oil-water separation performance of the modified wool and PVDF membrane is also explored.The coated wool can successfully separate different oil-water mixtures and the separation efficiency is above 99.99%,the flux is as high as 46000Lm-2h-1,and the separation efficiency can still be maintained above 99.99%after repeated separation for 100 times.The modified wool is still capable of maintaining a separation efficiency of more than 99.99%after 100 cycles of water washing,and the separation efficiency is still 99.98%through 150 cycles of abrasive paper surface friction.At the same time,the modified PVDF membrane can successfully separate toluene-water emulsion,and the separation efficiency reaches 99.6%.The water flux reaches 2700 Lm-2h-1 without external pressure.No significant decrease in separation efficiency and flux were observed after 30 cycles of repetition.2.Using a commercial microporous PVDF film as substrate,ethylene glycol acrylate?EGDA?as a cross-linking agent,and vinyl pyrrolidone?VP?as a hydrophilic functional agent,layered polymer thin films were synthesized.PEGDA homopolymer was designed as the bottom layer.The middle layer is cross-linked poly?vinyl pyrrolidone-co-ethylene glycol??P?EGDA-co-VP???A very thin layer of polyvinyl pyrrolidone?PVP?was grafted on the top.The static contact angle of the PVDF surface after being modified by the hydrophilic coating is 0°,and underwater superoleophobicity was achieved for four kinds of oils?vegetable.oil,toluene,hexane,and diesel oil?.The contact angles of the underwater oil are more than 155°.The oil-in-water emulsion of toluene-in-water?volume ratio 1:50?was successfully separated with a high permeation flux of 2780Lm-2h-1 under a pressure of 0.1MPa.The separation efficiency is as high as 99.8.%.After repeated separations of 20 times,high flux can still be maintained after simple rinse.After immersing in water with pH=0 and pH=14 for 2 hours,boiling for 2 hours,and ultrasonically for 2 hours,the separation efficiency of 99%can still be maintained,and the flux remains at 2500 Lm-2h-1.At the same time,the modified PVDF membrane has good anti-biofouling performance. |
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