Polystyrene (PS) that has been exposed to ultraviolet light (UV) undergoes partial dehydrogenation of the alkane polymer backbone which increases its surface energy. Exploiting this photochemistry, we exposed polystyrene films to UV light using a photomask to induce a patterned photochemical reaction producing regions in the film with differing surface energy. Upon heating the solid polymer film with the preprogrammed surface energy pattern to a liquid state, the polymer flows from the low surface energy unexposed regions to high surface energy exposed regions. This flow creates three-dimensional topography by the Marangoni Effect, which describes convective mass transfer due to surface energy gradients. The topographical features can be permanently preserved by quenching the film below its glass to liquid transition temperature. Their shape and organization are only limited by the pattern on the photomask.

Quantitative scaling analyses based on mass and energy transport analogies enable rate-limiting processes to be established in hyperpolarization transfer phenomena.

Tailorable sorption properties at the molecular level are key for efficient carbon capture and storage and a hallmark of covalent organic frameworks (COFs). Although amine functional groups are known to facilitate CO 2 uptake, atomistic insights into CO 2 sorption by COFs modified with amine-bearing functional groups are scarce. Herein, we present a detailed study of the interactions of carbon dioxide and water with two isostructural hydrazone-linked COFs with different polarities based on the 2,5-diethoxyterephthalohydrazide linker. Varying amounts of tertiary amines were introduced in the COF backbones by means of a copolymerization approach using 2,5-bis(2-(dimethylamino)ethoxy)terephthalohydrazide in different amounts ranging from 25 to 100% substitution of the original DETH linker. The interactions of the frameworks with CO 2 and H 2 O were comprehensively studied by means of sorption analysis, solid-state NMR spectroscopy, and quantum-chemical calculations. We show that the addition of the tertiary amine linker increases the overall CO 2 sorption capacity normalized by the surface area and of the heat of adsorption, whereas surface areas and pore size diameters decrease. The formation of ammonium bicarbonate species in the COF pores is shown to occur, revealing the contributing role of water for CO 2 uptake by amine-modified porous frameworks.

A Marangoni flow is shown to occur when a polymer film possessing a spatially-defined surface energy pattern is heated above its glass transition to the liquid state. This can be harnessed to rapidly manufacture polymer films possessing prescribed height profiles. To quantify and verify this phenomenon, a model is described here which accurately predicts the formation, growth, and eventual dissipation of topographical features. The model predictions, based on numerical solutions of equations governing thin film dynamics with a Marangoni stress, are quantitatively compared to experimental measurements of thin polystyrene films containing photochemically patterned surface energy gradients. Good agreement between the model and the data is achieved at temperatures between 120 and 140 °C for a comprehensive range of heating times using reasonable physical properties as parameter inputs. For example, thickness variations that measure 102% of the starting film thickness are achieved in only 12 minutes of heating at 140 °C, values that are predicted by the model are within 6% and 3 min, respectively. The photochemical pattern that directed this flow possessed only a 0.2 dyne cm(-1) variation in surface tension between exposed and unexposed regions. The physical insights from the validated model suggest promising strategies to maximize the aspect ratio of the topographical features and minimize the processing time necessary to develop them.