Fabrication Of Fluorinated Acrylate Polymer Brushes And Their Properties

Protein adsorption behavior onto the surface of solid materials is one of the topic issues. Tounderstand and manipulate the interactions between interfaces and proteins is of great concern inmany fields such as biomedical materials, antifouling and so on. As a typical material with lowsurface energy, fluorinated polymer was widely applied to antibiofouling coating. The excellentsurface properties of fluorinated polymers depend on the enrichment of fluorinated componentand array of perfluorooctylenthyl side chains on the surface. One of the key process to prepare amaterial with well protein-resistant performance is to construct a fluorinated surface withhighly-ordered structure.In this thesis, methyl methacrylate (MMA), octadecyl methacrylate (ODMA) and2-perfluorooctylethyl methacrylate (FMA) copolymers with a disulfide group were synthesizedby atom transfer radical polymerization (ATRP), then the fluorinated polymers were attached toAu substrate using “grafting to” method. The “pull you” effect could be reinforced by formingcovalent bond between the disulfide groups in polymer chain and Au substrate. The “push me”effect could be reinforced by the crystallizability of PODMA block. Due to the “push me/pullyou” effect, the limited fluorinated group with highly-ordered structure were packed on thesurface. Drop shape analysis, ellipsometry, X-ray photoelectron spectroscopy, Atomic ForceMicroscopy Peak force QNM mode were used to systematically investigate the surface structureand protein-resistant performance of fluorinated polymer brush. Some conclusions were obtainedas follows:(1) Fluorinated copolymers with a disulfide group were synthesized by atom transfer radicalpolymerization (ATRP) and their chemical structures were characterized precisely. Fluorinatedacrylate polymer brushes (Au-PMMA126-b-PFMAn, Au-PODMA103-b-PFMAn, Au-PMMA65-b-PODMAy-b-PFMA1.5) were successfully prepared on Au substrate by “grafting to” method.(2) For the diblock polymer brushes, the fluorinated groups of Au-PODMA103-b-PFMAnpolymer brush surfaces were much more ordered than that of Au-PMMA126-b-PFMAnsurfaces.The contact angles、F/C values、CF3/CF2values of Au-PODMA103-b-PFMAnsurfaces were alllarger than those of Au-PMMA126-b-PFMAnsurfaces. The introduction of PODMA block with a special crystallinity because of a long alkyl side chain, could contribute to the segregation of theperfluorinated alkyl groups and the formation of a well-ordered structure on the surface.(3) For the triblock polymer brushes, the fluorinated groups of Au-PMMA65-b-PODMA24-b-PFMA1.7polymer brushes surfaces were more ordered than that ofAu-PODMA103-b-PFMA2.1surfaces. The contact angles、 F/C values、 CF3/CF2values ofAu-PMMA65-b-PODMA24-b-PFMA1.7surfaces were all larger than those of Au-PODMA103-b-PFMA2.1surfaces. PMMA block which acted as a “lubricant” between a solid substrate and acrystalline PODMA block could further improve the ordering of the fluorinated groups.(4) The fluorinated groups on Au-PMMA65-b-PODMAy-b-PFMA1.5polymer brushessurfaces became more ordered as polymerization degree of PODMA (y) increased. The contactangles、F/C values、CF3/CF2values of Au-PMMA65-b-PODMAy-b-PFMA1.5became larger withthe increasement of polymerization degree of PODMA (y). As known from the results ofpolymer brushes’ modulus test, PODMA began to form crystal structure as polymerizationdegree of PODMA (y) increased, and then it promoted the formation of PFMA’s orderedstructure.(5) There was a linear relationship between amount of adsorbed protein onto polymerbrushes and orientation of fluorinated group. It suggested that when the CF3/CF2value was larger,the amount of adsorbed protein on fluorinated surface was less. Human fibrinogen and bovineserum albumin adsorption test showed Au-PMMA65-b-PODMA24-b-PFMA1.7had betterprotein-resistant performance than Au-PODMA103-b-PFMA2.1and Au-PMMA126-b-PFMA2.4.Flexible PMMA block and crystal PODMA block enhanced the “push me/pull you” effect. Sothe well protein-resistant performance resulted from the highly-ordered fluorinated groups. Theprotein-resistant performance of the fluorinated materials could be controlled by manipulatingthe fluorinated side chains’packing on the surface.