Synthesis And Surface Property Of Environment-friendly Fluorinated Polymers

Fluoropolymer is one of the synthetic polymeric materials with excellent comprehensive performance that has been discovered.The unique chemical and physical properties of the polymer,such as extraordinarily low surface energy,low friction coefficient,superior chemical resistance and low refractive index,make it be applied widely to various fields.However,with the rapid social and economic development,higher requirements are put forward for materials.Although fluorinated polymers have widely been applied,there are some urgent problems need to be solved.A number of research revealed that perfluoroalkyl compounds containing more than 7 carbon atoms are difficult to degrade in nature,and lead to bioaccumulation and toxicity.Thus,these compounds have been forbidden in many countries.The fluorinated polymers containing long perfluorocarbon chains also suffer from the problem of environmental security.The polymers containing short perfluorocarbon chains are not considered as no environmental hazard,but their performance can hardly meet the requirements for practical application.Therefore,it is urgent to find alternatives for the polymers containing a long perfluoroalkyl group.In this dissertation,from the view of effective utilization of energy and resource,environmental security and sustainable development,in order to solve the problems in the synthesis and applications of fluorinated polymers,we carried out the present research work,including developing a highly efficient method for synthesis of acrylate monomers containing short perfluoroalkyl groups,investigating the anti-fogging and self-cleaning properties of fluorinated block polymer coatings,synthesizing high-performance fluorinated polymers with the perfluoropolyether and the short perfluoroalkyl compounds.1.The synthesis of fluorinated(methyl)acrylate is of top importance for the development of fluorinated poly(methyl)acrylate.However,acids,such as sulfuric acid,are usually used as catalysts for the esterification,which can lead to severe environmental problems and equipment corrosion.Therefore,it is important to develop an environment-friendly and highly efficient method for synthesis of fluorinated acrylates.Thus,we investigated the effect of different catalysts for the esterification of acrylic acid with short-chain fluoroalkyl alcohols.The results indicated that ZrOCl2·8H2O is an efficient and environment-friendly catalyst for the reaction in comparison of sulfuric acid.2.The fogging on the surface of transparent materials such as eyeglasses,display screen,windshield,and camera lens,would surely bring people numerous inconveniences or even cause serious accidents.It is still a challenge to make transparent materials have long-lasting anti-fogging and anti-fouling property.It has been demonstrated that hydrophilic-oleophobic fluoropolymer possesses anti-fogging and oil-repelling property,which is considered to be a promising candidate material for achiving the long-lasting anti-fogging.Therefore,we selected hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate as comonomers to polymerize with hydrophilic dimethylaminoethyl methacrylate and hydroxyethyl methacrylate and prepared the random copolymers and the block copolymers.Then,anti-fogging and oil-repelling properties of the polymer coatings were examined.The results indicated that the hydrophilicity of the polymer coatings decreased,but the oleophobicity increased with a higher content of the fluorinated monomer in both the random and block copolymers.The anti-fogging and oil-repelling effect can be achieved by tuning the content of the fluorinated monomer and the hydrophilic monomer.Compared to the random copolymer,the block copolymer exhibits better anti-fogging and oil-repelling properties with low content of the fluorinated monomer.3.Perfluoropolyethers are considered to be suitable materials for their low surface energy and environment-friendly nature.However,the flexible perfluoropolyether with low molecular weight are hard to form stable aggregate structure on the coating surface because of chain rearrangement which can lead to low oil-repelling property.Based on the principle of the intermolecular interactions,we tried to improve the surface properties of low-molecular weight perfluoropolyether coating by designing novel perfluoropolyethers with high interaction between the side-chain of the polymers to suppress the chain rearrangement.Therefore,we synthesized three macromonomers of perfluoropolyether with different molecular weight and different spacers.The polymer coating was prepared by UV-initiated polymerization,and then the relationship between the structure of the macromonomers and the surface properties of the coating has been studied.The results indicated that the hydrophobicity and oleophobicity can be improved by hydrogen-bonding and π-π interaction of the aromatic rings,which can effectively suppress the motion and the rearrangement of the polymer chains.This work has demonstrated that the poor surface properties of low molecular weight perfluoropolyethers can be improved by rational design of molecular structure.4.In order to solve the environmental issues caused by the polymers with long perfluoroalkyl chains,three kinds of short fluoroalkylcarbonyl fluorides CF3(CF2)nCOF were used as raw materials to design and synthesize 5 monomers with short fluoroalkyl chain and different spacers.Then,polymer coatings were prepared by photo-polymerization of the fluorinated monomers with crosslinkers and the surface property of the coatings was examined.The results revealed that the hydrophobicity and oleophobicity of the coatings can be effectively promoted by incorporating amide bonds and aromatic rings into the polymers,suppressing the motion and rearrangement of the polymer chains.For example,polymer P6-1 with fluorohexyl groups shown excellent hydrophobic and oleophobic property,with water and oil contact angles of 103.4° and 64.9° respectively,which are higher than that of a well-known polymer,poly(perfluorooctylethyl methacrylate)with excellent hydrophobic and oleophobic property.This work demonstrated that the surface property of the short fluorocarbon chain polymers can be as excellent as that of the long fluorocarbon chain polymers by rational design of the monomer structure.