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Overview and status of the 0.5NA EUV microfield exposure tool at Berkeley Lab
A 0.5-NA extreme ultraviolet micro-field exposure tool has been installed and commissioned at beamline 12.0.1.4 of the Advanced Light Source synchrotron facility at Lawrence Berkeley National Laboratory. Commissioning has demonstrated a patterning resolution of 13 nm half-pitch with annular 0.35-0.55 illumination; a patterning resolution of 8 nm half-pitch with annular 0.1-0.2 illumination; critical dimension (CD) uniformity of 0.7 nm 1Ď on 16 nm nominal CD across 80% of the 200 um x 30 um aberration corrected field of view; aerial image vibration relative to the wafer of 0.75 nn RMS and focus control and focus stepping better than 15 nm
New insights into the development and differentiation of the human anorectal epithelia. Are there clinical consequences?
RAFT aqueous dispersion polymerization yields poly(ethylene glycol)-based diblock copolymer nano-objects with predictable single phase morphologies
A poly(ethylene glycol) (PEG) macromolecular chain transfer agent (macro-CTA) is prepared in high yield (>95%) with 97% dithiobenzoate chain-end functionality in a three-step synthesis starting from a monohydroxy PEG113 precursor. This PEG113-dithiobenzoate is then used for the reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA). Polymerizations conducted under optimized conditions at 50 °C led to high conversions as judged by 1H NMR spectroscopy and relatively low diblock copolymer polydispersities (Mw/Mn < 1.25) as judged by GPC. The latter technique also indicated good blocking efficiencies, since there was minimal PEG113 macro-CTA contamination. Systematic variation of the mean degree of polymerization of the core-forming PHPMA block allowed PEG113-PHPMAx diblock copolymer spheres, worms, or vesicles to be prepared at up to 17.5% w/w solids, as judged by dynamic light scattering and transmission electron microscopy studies. Small-angle X-ray scattering (SAXS) analysis revealed that more exotic oligolamellar vesicles were observed at 20% w/w solids when targeting highly asymmetric diblock compositions. Detailed analysis of SAXS curves indicated that the mean number of membranes per oligolamellar vesicle is approximately three. A PEG 113-PHPMAx phase diagram was constructed to enable the reproducible targeting of pure phases, as opposed to mixed morphologies (e.g., spheres plus worms or worms plus vesicles). This new RAFT PISA formulation is expected to be important for the rational and efficient synthesis of a wide range of biocompatible, thermo-responsive PEGylated diblock copolymer nano-objects for various biomedical applications
Polymerization-induced self-assembly of block copolymer nanoparticles via RAFT non-aqueous dispersion polymerization
There is considerable current interest in polymerization-induced self-assembly (PISA) via reversible additionâfragmentation chain transfer (RAFT) polymerization as a versatile and efficient route to various types of block copolymer nano-objects. Many successful PISA syntheses have been conducted in water using either RAFT aqueous dispersion polymerization or RAFT aqueous emulsion polymerization. In contrast, this review article is focused on the growing number of RAFT PISA formulations developed for non-aqueous media. A wide range of monomers have been utilized for both the stabilizer and core-forming blocks to produce diblock copolymer nanoparticles in either polar or non-polar media (including supercritical CO2 and ionic liquids) via RAFT dispersion polymerization. Such nanoparticles possess spherical, worm-like or vesicular morphologies, often with controllable size and functionality. Detailed characterization of such sterically stabilized diblock copolymer dispersions provides important insights into the various morphological transformations that can occur both during the PISA synthesis and also on subsequent exposure to a suitable external stimulus (e.g. temperature)
RAFT polymerization of hydroxy-functional methacrylic monomers under heterogeneous conditions: effect of varying the core-forming block
Statistical copolymerization of a 1 : 1 molar ratio of a water-miscible monomer (2-hydroxyethyl
methacrylate, HEMA) with a water-immiscible monomer (4-hydroxybutyl methacrylate, HBMA) has been
conducted in water via reversible additionâfragmentation chain transfer (RAFT) polymerization using a
water-soluble poly(glycerol monomethacrylate) macromolecular chain transfer agent (PGMA macro-
CTA). In principle, such a hybrid formulation might be expected to be intermediate between RAFT
dispersion polymerization and RAFT emulsion polymerization. Under such circumstances, it is of
particular interest to examine whether both monomers are actually consumed and, if so, whether their
rates of reaction are comparable. Given the water-solubility of both the PGMA macro-CTA and the free
radical azo initiator, it is perhaps counter-intuitive that the water-immiscible HBMA is initially consumed
significantly faster than the water-miscible HEMA, as judged by 1H NMR studies of this copolymerization.
However, both comonomers are eventually almost fully consumed at 70 �C. A detailed phase diagram
has been constructed for this RAFT formulation that enables reproducible syntheses of various pure
copolymer morphologies, including spheres, worms and vesicles. It is emphasized that utilizing a 1 : 1
HEMA/HBMA molar ratio produces a core-forming statistical copolymer block that is isomeric with the
poly(2-hydroxypropyl methacrylate) (PHPMA) core-forming block previously synthesized via RAFT
aqueous dispersion polymerization (see A. Blanazs et al., Macromolecules, 2012, 45, 5099â5107). Hence
it is rather remarkable that the thermo-responsive behavior of PGMAâP(HBMA-stat-HEMA) statistical
block copolymer worm gels differs qualitatively from that exhibited by PGMAâPHPMA diblock copolymer
worm gels
Was leistet der seitliche Zugangsweg zur Fl�gelgaumengrube, Fossa infratemporalis und Orbita?
Eine zweite Larvenschlupfwelle bei Heuschrecken - ein Beitrag zur Populationsbiologie von Psophus stridulus und Myrmeleotettix maculatus (Orthoptera: Acrididae)
Zur Bedeutung von FlieĂgewässer-Dynamik fĂźr naturnahe Rheinufer unter besonderer Betrachtung der Schwarzpappel (Populus nigra) und Sandrasen
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