Development, Processing and Applications of a UV-Curable Polymer with Surface Active Thiol Groups

Abstract

We present here a novel resist formulation with active thiol groups at the surface. The material is UV curable, and can be patterned at the micro- and nanoscale by UV nanoimprint lithography. The resist formulation development, its processing, patterning and surface characterization are presented here. In addition, a possible application, including its use to modify the electrical properties of graphene devices is shown. The cured material is highly transparent, intrinsically hydrophilic and can be made more hydrophilic following a UV-ozone or an O2 plasma activation. We evaluated the hydrophilicity of the polymer for different polymer formulations and curing conditions. In addition, a protocol for patterning of the polymer in the micro and nanoscale by nanoimprinting is given and preliminary etching rates together with the polymer selectivity are measured. The main characteristic and unique advantage of the polymer is that it has thiol functional groups at the surface and in the bulk after curing. These groups allow for direct surface modifications with thiol-based chemistry e.g., thiol-ene reactions. We prove the presence of the thiol groups by Raman spectroscopy and perform a thiol-ene reaction to show the potential of the easy “click chemistry”. This opens the way for very straightforward surface chemistry on nanoimprinted polymer samples. Furthermore, we show how the polymer improves the electrical properties of a graphene field effect transistor, allowing for optimal performance at ambient conditions.

Editorial for Special Issue: Nanoimprint Lithography Technology and Applications

“…One of the exciting things about nanoimprinting is the big versatility of the process and the broad range of applications it can be used for. This special issue includes 10 articles [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ] which represent a small glimpse of the challenges and possibilities of this technology.…”

“…Six contributions deal with nanoimprint processes aiming at specific applications [ 2 , 4 , 6 , 8 , 9 , 10 ], while the other four papers focus on more general aspects of nanoimprint processes [ 3 , 5 , 7 ] or present novel materials [ 1 , 3 ]. Several different types of nanoimprint processes are used: plate-to-plate [ 1 , 2 , 3 , 5 , 7 , 10 ], roll-to-plate [ 4 , 6 ], and roll-to-roll [ 8 ]. Plate-to-plate NIL here also includes the use of soft and flexible stamps.…”

“…Müller et al [ 1 ] report a UV-curable polymer with surface active thiol groups. Such type of materials can open up additional applications and functionalities for nanoimprinting.…”

“…In summary the application fields in this special issue can be identified as plasmonics [ 2 ], superhydrophibicity [ 4 ], biomimetics [ 4 , 9 , 10 ], optics/datacom [ 6 ], and life sciences [ 8 ]. The nanoimprint process related papers discuss filling and wetting aspects during nanoimprinting [ 3 , 5 , 7 ] as well as materials for stamps [ 3 ] and imprinting [ 1 ].…”