Patterned Polyfluorene Surfaces by Functionalization of Nanoimprinted Polymeric Features

Abstract

A new procedure is described for surface grafting polymer brushes by step-growth polymerization from initiator-embedded polymeric thin films and micron- and nanometer-scale patterns. An imprint lithographic process, nanocontact molding, was used to prepare thin patterned cross-linked polyacrylate network films on silicon wafers that incorporated 4-bromostyrene in the networks. These networks present reactive 4-bromophenyl functionality at the surface that act as attachment sites for the subsequent Ni(0)- mediated step-growth condensation polymerization of 2,7-dibromo-9,9-dihexylfluorene The step-growth polymerization medium consisted of 2,7-dibromo-9,9-dihexylfluorene, Ni(0)-catalyst, and bipyridine in a toluene/dimethylformamide solvent mixture. The resulting growth of polydihexylfluorene brushes from the patterned surface was monitored by contact angle, optical spectrometry, surface profilometry and AFM. Brush growth was conducted from patterned features ranging from 100 microm to 100 nm in width and 50 nm in height. The optical and fluorescence behavior of the polyfluorene brushes was similar to that of thin polyfluorene films made by spin coating.

Kumada Catalyst‐Transfer Polycondensation: Mechanism, Opportunities, and Challenges

“…Yamamoto step-growth polycondensation, [106,107] only thin grafted layers can be formed under harsh reaction conditions, and a predominant quantity of ungrafted polymer forms as well. The surface-initiated polymerization (SIP, or ''grafting-from'') technique usually results in significantly thicker films and can be easily applied to fabricate patterned substrates.…”

Chain-End Functionalized Nanopatterned Polymer Brushes Grown via in Situ Nitroxide Free Radical Exchange

“…13,15,38 Molds containing arbitrary test patterns with features ranging from 100 nm to 10 m were used. An optical micrograph image of the original silicon used in the nanocontact molding process is shown in Figures 5a, and a close-up of the 75 nm wide lines is shown in Figure 5b (SEM).…”

“…Patterned layers of polyflurorene grafts have also been made by an extension of this technique. 14 In a recent report, the utility of the patterning of polymers with embedded functionality to create metallic nanostructures has been described. 15 This current paper concerns a careful examination of the use of NCM to pattern a functional resin that is subsequently converted into a scaffold for the selective recognition and attachment of streptavidin protein.…”

Durch oberflächeninitiierte Suzuki‐Polykondensation zu gepfropftem Polyfluoren

“…[1b] Carter et al [3] beschrieben kürzlich eine "polymerization-onto"-Methode einer Yamamoto-Stufenwachstumspolykondensation, bei der in situ wachsende Polyfluorenketten auf entsprechend modifizierte Oberflächen gepfropft wurden. Allerdings konnten mit diesem Ansatz, auch unter harschen Reaktionsbedingungen, nur dünne gepfropfte Filme präpariert werden.…”

“…Mit unserer Methode kann PF2/6 auf oberflächen-gebundene PS(Br)-Filme, auf Monoschichten niedermolekularer Initiatoren oder auf strukturierte Initiatoren gepfropft werden (Schema 1 b). Anders als frühere "polymerizationonto"-Methoden [3,6] startet der hier beschriebene Prozess selektiv an der Oberfläche; es werden keine detektierbaren Mengen an Polymer in Lösung gebildet. Die Polymerisation verläuft bereits bei Raumtemperatur sehr schnell, und es sind gepfropfte PF2/6-Filme [12] mit Schichtdicken von bis zu 100 nm zugänglich.…”