(555h) Using Cross-Section Surfaces of Polymeric Multilayer Films as a Nanopatterning Template

Highly layered structures are important to microfabrication and nanofabrication technologies as tools for understanding and controlling surface structures through manipulation of chemical and physical interactions. A new approach is introduced to create nanoscale patterned surfaces with surface chemical functionality using multilayer polymer films. Alternating layer structures of two polymers, non-reactive linear low density polyethylene (LLDPE) and reactive ethylene-co-acrylic acid copolymer (EAA), were formed by co-extrusion with subsequent compression molding. Thin sections of the multilayer molded sheets were prepared by microtoming to reveal the alternating nanostripe pattern, and the highly layered nanostructure was verified by transmission electron microscope (TEM), and polarized optical microscopy.

To increase the density of surface functional groups on the alternating reactive EAA layers, poly(allyamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) were adsorbed layer-by-layer on top of pretreated EAA layers. Subsequent cross-linking of the polyelectrolyte multilayers (PEMS) was conducted to improve its stability by using N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). In addition, the activated carboxylic acids on the surface were able to react with amine-ended species for various functionalities, which was confirmed by covalent grafting with amine-ended fluorescein isothiocyanate (FITC) and imaged by confocal fluorescence microscopy. This multilayer film approach can potentially be used for patterning small biological ligands and proteins for biomaterial and biotechnology applications.