Atom Transfer Radical Polymerization (atrp) In The Multi-function Silicon (100) Surface Modification Of Materials

Tethering of polymer brushes on a solid substrate is an effective method of modifying the surface properties of the substrate. It is very important of that the manipulation and control of the physicochemical properties of single-crystal silicon surfaces because of their crucial requirement to the modern microelectronics industry. In many cases, the dense polymer brushes can serve as an effective etching barrier in the microlithographic process, provide excellent mechanical and chemical protection of the substrate, alter the electrochemical interface characteristics of the substrate, and provide new pathways to the functionalization of silicon surfaces for molecular recognition and sensing. Considerable attention has been paid to the modified oriented single crystal silicon with covalently bonded amphiphilic and hydrophilic polymer brushes. The approach provides new potential application and new pathways to functionalize silicon surface for molecular recognition, biochip and biosensing device.The synthesis of polymers with well-defined compositions, architectures, and functionalities has long been of great interest in polymer chemistry. With the progress in polymerization methods, it is possible to prepare welldefined graft polymer chains on various substrate surfaces by atom transfer radical polymerization (ATRP). ATRP is a recently developed "living" radical polymerization method, involving a copper halide/nitrogen-based ligand catalyst. The method does not require stringent experimental conditions, as in the case of cationic and anionic polymerization. This controlled radical polymerization technique allows for the polymerization and block copolymerization of a wide range of functional monomers, such as styrene, acrylates, and methacrylates in a controlled fashion, yielding polymers with narrowly dispersed molecular weights, predetermined by the concentration ratio of the consumed monomer to initiator. There are a number of reports in the literature dealing with the modification of silicon surfaces by ATRP. Surface initiators were immobilized on the oxidized silicon surface, the hydrogenterminated silicon surface, or the monolayer-modified silicon wafer, usually in multistep processes.Various tophology of polymer brushes contains linear, branched, comb-shaped, dendritic, and three-arm star polymer burshes. They has been successfully prepared by (i) UV-induced coupling combining the esterification and acylate produce the initiate-functional siliconsurfaces, which include Si-VBC, Si-TVPBA-R₃Br, Si-VBC-g-P(HEMA)-R₃Br and Si-TVPBA-g-P(HEMA)-R₃Br surface; (ii) surface-initiated ATRP of 2-hydroxyethl methacrylate (HEMA), styrene (St), poly(ethylene glycol) monomethacrylate (PEGMA) and 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) to give covalently bonded polymer brushes on Si(100) surface; (iii) Kinetics study indicated that the chain growth of poly(2-hydroxyethl methacrylate) (P(HEMA)), polystyrene (PS), poly(poly(ethylene glycol)) (P(PEGMA)) and poly(2,2,3,3,4,4,4-heptafluorobutyl acrylate) P(HFBA) from the initiate- functionalized silicon surfaces was consistent with a "controlled" or "living" process; (iv) The chemical composition of the modified silicon surfaces were characterized by X-ray photoelectron spectroscopy (XPS), the topography were examined by the tapping atomic force (AFM) Other analysis of diblock copolymer brush layers was conducted using ellipsometry and contact angle measurements; and (v) The Si-VBC-g-P(PEGMA)-6-P(HEMA)-g-P(HFBA) and Si-VBC-g-P(HFBA)-b- P(HEMA)-g-P(PEGMA) surface show that their morphology depends the solvent properties treated with. AFM imaging of these amphiphilic block polymer brushes imaged different morphology when they were treated with different solvents. The images suggest the materials do undergo the rearrangement mechanism to form pinned micelles on the surface when treated them with not good solvent, and the intrinsic hydrophobic and hydrophilic properties play some role in their rearrangement. We presume that the manner of aggregation might be localized to the near-surface region, and in terms of the half-imbedding model. XPS spectra of before and after the solvent treatment elementarily confirm that the presumption about the half-imbedding model is reasonable.