Formation And Tribological Study Of Biocompatible Polymeric Coatings

In this work, internally cross-linked polymer films were grown from silicon surfaces modified with aconventional initiator via a simple approach, and polymer micelles films were prepared on theamino-functionalized substrates by chemical deposition too. Friction properties of films were characterizedto explore the intrinsic and extrinsic factors that can affect polymer film tribology, and to reveal theultra-low friction mechanism of polymer in biological systems.(1) methoxy poly(ethylene glycol)-block-poly(lactic-co-glycolic acid)(mPEG-b-PLGA)micelles/Poloxamer(F127) micelles and poly(acrylic acid)(PAA) layers are alternately deposited on thesilicon substrate, linked by hydrogen bonds. The structure of the micelles films were characterized bycontact angle measurements, ellipsometric thickness measurements and X-ray photoelectronic spectroscopy,atomic force microscopy. Anti-wear properties of the films were also evaluated on a ball-on-platetribometer. It was found that the mPEG-b-of PLGA micelle films were uniformly deposited and offeredexcellent lubrication. There is a possibility of such thin films as anti-inflaming and lubricating coating usedon catheter or device implanted in vivo.(2) Hydrogel polymer films system with limited surface, internally cross-linked and three-dimensionalnet-like was prepared through Surface-initiated atom transfer radical polymerization (SI-ATRP). Amolecule containing functional group (acrylate group) was selected as a monomer or a cross-linking agent.In SI-ATRP, chain growth started from an ATRP initiator that was immobilized on a substrate. As activeradical groups connected to acrylate groups in chain growth process, different polymer chains weregrowing and crosslinking, then different chemical structure of the hydrogel films were prepared The ratiobetween the monomer and the crosslinking agent influenced chemical structure of polymer films. AfterContact angle measurement, ellipsometry thickness measurement, X-ray photoelectron spectroscopy andatomic force microscopy characterization, the polymer films with different chemical composition, internalstructure and surface morphology were knew. Finally, the tribological behavior of the gel films wasexamined on UMT-2. It is found that three-dimensional net hydrogel polymer film having a certain degreeof crosslinking was successfully prepared. As polymer film surface roughness increased in the amount of a difunctional crosslinking agent, the film absorbent decreased; tribological test results shown that the gelfilm with a certain degree of crosslinking offered excellent lubrication.