In this paper, we
describe the use of liquid cell transmission
electron microscopy (LCTEM) for inducing and imaging the formation
of spherical micelles from amphiphilic block copolymers. Within the
irradiated region of the liquid cell, diblock copolymers were produced
which self-assembled, yielding a targeted spherical micellar phase
via polymerization-induced self-assembly (PISA). Critically, we demonstrate
that nanoparticle formation can be visualized in situ and that in
the presence of excess monomer, nanoparticle growth occurs to yield
sizes and morphologies consistent with standard PISA conditions. Experiments
were enabled by employing automated LCTEM sample preparation and by
analyzing LCTEM data with multi-object tracking algorithms designed
for the detection of low-contrast materials.
Herein we report a polymerization-induced self-assembly (PISA) process with ring-opening metathesis polymerization (ROMP). We utilize a peptide-based norbornenyl monomer as a hydrophobic unit to provide a range of nanostructures at room temperature yet at high solids concentrations of 20 wt % in combination with an oligoethylene glycol based norbornenyl monomer. Evaluation of the polymerizations under mild conditions highlight that good control is maintained along with high monomer conversion of greater than 99%, indicating that the living polymerization is unaffected during the PISA process. The demonstration broadens the scope of the PISA process to a new living polymerization methodology toward the development of easily accessible and highly functionalized nanostructures in situ.
Polymer brush patterns have a central role in established and emerging research disciplines, from microarrays and smart surfaces to tissue engineering. The properties of these patterned surfaces are dependent on monomer composition, polymer height, and brush distribution across the surface. No current lithographic method, however, is capable of adjusting each of these variables independently and with micrometer-scale resolution. Here we report a technique termed Polymer Brush Hypersurface Photolithography, which produces polymeric pixels by combining a digital micromirror device (DMD), an air-free reaction chamber, and microfluidics to independently control monomer composition and polymer height of each pixel. The printer capabilities are demonstrated by preparing patterns from combinatorial polymer and block copolymer brushes. Images from polymeric pixels are created using the light reflected from a DMD to photochemically initiate atom-transfer radical polymerization from initiators immobilized on Si/SiO 2 wafers. Patterning is combined with high-throughput analysis of grafted-from polymerization kinetics, accelerating reaction discovery, and optimization of polymer coatings.
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