Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons.

Reactive molecular dynamics simulations are used to model the covalent functionalization of amorphous silica with aromatic hydrocarbons. Simulations show that the surface density of silanol-terminated phenyl, naphthyl, and anthracenyl molecules is lower than the maximum value calculated based on molecule geometry, and the simulation densities decrease faster with the number of aromatic rings than the geometric densities. The trends are analyzed in terms of the surface-silanol bonding configurations, tilt angles, local conformational ordering, and aggregation of surface-bound molecules under steady-state conditions.

Acceleration of Diels-Alder reactions by mechanical distortion.

Challenges in quantifying how force affects bond formation have hindered the widespread adoption of mechanochemistry. We used parallel tip-based methods to determine reaction rates, activation energies, and activation volumes of force-accelerated [4+2] Diels-Alder cycloadditions between surface-immobilized anthracene and four dienophiles that differ in electronic and steric demand. The rate dependences on pressure were unexpectedly strong, and substantial differences were observed between the dienophiles.

Glycopolymer Microarrays with Sub-Femtomolar Avidity for Glycan Binding Proteins Prepared by Grafted-To/Grafted-From Photopolymerizations.

We report a novel glycan array architecture that binds the mannose-specific glycan binding protein, concanavalin A (ConA), with sub-femtomolar avidity. A new radical photopolymerization developed specifically for this application combines the grafted-from thiol-(meth)acrylate polymerization with thiol-ene chemistry to graft glycans to the growing polymer brushes. The propagation of the brushes was studied by carrying out this grafted-to/grafted-from radical photopolymerization (GTGFRP) at >400 different conditions using hypersurface photolithography, a printing strategy that substantially accelerates reaction discovery and optimization on surfaces.

Orthogonal Images Concealed Within a Responsive 6-Dimensional Hypersurface.

A photochemical printer, equipped with a digital micromirror device (DMD), leads to the rapid elucidation of the kinetics of the surface-initiated atom-transfer radical photopolymerization of N,N-dimethylacrylamide (DMA) and N-isopropylacrylamide (NIPAM) monomers. This effort reveals conditions where polymer brushes of identical heights can be grown from each monomer. With these data, hidden images are created that appear upon heating the substrate above the lower critical solution temperature (LCST) of polyNIPAM.