The ability to create aqueous suspended stable nanoparticles of the hydrophobic homopolymer poly(ϵ-caprolactone) end-functionalized with coumarin moieties (CPCL) is demonstrated. Nanoparticles of CPCL are prepared in a continuous manner using nanoprecipitation. The resulting nanoparticles are spherical in morphology, about 40 nm in diameter, and possess a narrow size distribution and excellent stability over 4 months by repulsive surface charge. Nanoparticle size can be easily controlled by manipulating the concentration of CPCL in the solution. The interparticle assembly between the nanoparticles can be reversibly adjusted with photoirradiation due to photoinduced [2 + 2] cyclodimerization and cleavage between the coumarin molecules. In addition, the CPCL nanoparticles show significant cellular uptake without cytotoxicity, and the intrinsic fluorescence of the coumarin functional group permits the direct detection of cellular internalization.
In an effort to improve upon the sensitivity of commercial non-chemically amplified e-beam resists, four polyacrylates functionalized with α-CF 3 and/or CH 2 CF 3 alkoxy substituents were studied. The α-CF 3 substituent is known to increase backbone-scission efficiency while simultaneously eliminating acidic out-gassing and cross-linking known to occur in α-halogen substituted polyacrylates. Contrast curves for the polymeric α-CF 3 acrylates, generated through e-beam exposure, showed the resists required an order of magnitude less dose than the current industry-standards, PMMA and ZEP. The fundamental sensitivity of these materials to backbone scissioning was determined via 60 Co γ-ray irradiation. The chain scissioning, G(s), and cross-linking, G(x), values calculated from the resulting change in molecular weight demonstrated that all fluorinated resists possess higher G(s) values than either PMMA or ZEP and have no detectable G(x) values. Utilizing e-beam and EUV interference lithographies, the photospeed of PMTFMA was found to be 2.8x and 4.0x faster, respectively, than PMMA.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.