The Preparation And Characterization Of Patterned Polymer Brushes

In recent years, advances in nanoscience and nanotechnology require a simple andrapid technique to fabricate organic thin films on solid surfaces in order to modify thechemical and physical properties of the surface, such as wettability, adsorptionbehavior, thermal stability, bioactivity, etc, without changing the bulk properties of thematerial.In general, people tailor the surface chemistry of material through a way that graftmolecules or polymers onto the surface of solid materials. Grafting molecules onto thesurface, that is, put molecules onto the surface through chemical binding to formself-assembled monolayers. The spontaneous organic assembly of small molecules onsurface offers a convenient, flexible and simple system to modify the intrinsicproperties of the surface. However, the main drawback of SAMs lies in somemechanical and chemical instability due to the very limited thickness of the resultingcoatings, so it s urgent that appear a new way to prepare chemical stable coatings onthe surface of materials. A relevant technique to overcome these restrictions consists ofthe preparation of thicker organic films such as polymer brushes.In this paper, we use grafting from methods which combined withself-assembled monolayers(SAMs), microcontact printing and surface-initiated atomtransfer radical polymerization(SI-ATRP) to prepare patterned polymer brushes inorder to tailor the chemical and physical properties of the substrate in a reliable way.This will pave the way to study the adsorption and migration behavior of cells. Firstly,combined microcontact printing with self-assembled monolayers(SAMs), we anchored1-octadecanethiol and initiator bis[2-(2-bromoisobutyryloxy)undecyl] disulfide(DTBU)onto the gold surface to prepare patterned initiator monolayer. Then through atomtransfer radical polymerization, we respectively successfully sythesized patternedpoly(N-isopropylacrylamide)(PNIPAAm) polymer brushes and patterned poly(4-vinylpyridine)(P4VP) polymer brushes on the patterned initiator monolayer. In theprocess of preparing PNIPAAm polymer brushes, we find that the thcikness of polymerbrushes is proportional to the time of polymeric reaction in a certain range. And whenconducting microcontact printing, we concluded that the pressure given to PDMSstamp should be appropriate，10N maybe the best. Secondly, we synthesized adopamine derivative-2-bromo-2-methyl-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-propion-amide, which can be bonded to versatile material surfaces at high binding strengththrough catechol group and can be used as initiator in the reaction of ATRP. So, in myexperiment, we printed the2-bromo-2-methyl-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-pro- pionamide onto the silicon wafer to form patterned initiator monolayer. Then weprepared patterned PNIPAAm polymer brushes on the substrate through ATRP.