The glass transition temperature (T g ), in-plane diffusivity (D), and effective viscosity (η eff ) were measured for the same thin film system of poly(isobutyl methacrylate) supported by silica (PiBMA/SiOx). We found that both the T g and D were independent of the film thickness (h 0 ), but η eff decreased with decreasing h 0 . We envisage the different h 0 dependencies to be caused by T g , D, and η eff being different functions of the local T g 's (T g,i ) or viscosities (η i ), which vary with the film depth. By assuming a three-layer model and that T g (h 0 ) = ⟨T g,i ⟩, D(h 0 ) ∼ k B T/⟨η i ⟩, and η eff (h 0 ) = h 0 3 /3M tot (η i ), where ⟨...⟩ denotes spatial averaging and M tot is the mobility of the films, we were able to account for the experimental data. By extending these ideas to the analogous data of polystyrene supported by silica (PS/SiOx), a resolution was found for the long-standing inconsistency regarding the effects of confinement on the dynamics of polymer films.

In this study, key factors for controlling the average fiber diameter and diameter distribution of fibers made via simultaneous centrifugal spinning and UV initiated polymerization are elucidated. Through systematic investigation, it was found that average fiber diameter has a strong dependence on monomer delivery rate through the orifice, which can be intuitively linked to both the orifice diameter and monomer mixture viscosity. On the other hand, the breadth of the fiber diameter distribution can be controlled by the spin speed of the rotating spinneret. Carefully tuning these process parameters allows near independent control of fiber diameter and its distribution, which could provide access to a widely tailorable range of fiber diameters and diameter distributions appropriate for different applications. Finally, under optimized process conditions, crosslinked fibers with average diameters of approximately 1.5 µm can be produced, which are one to two orders of magnitude smaller than photocured fibers fabricated in previous reports and comparable with the smallest melt blown nonwoven fibers produced commercially. Coupled with the advantages of cross-linked fibers made by in-situ photopolymerization, the capability to produce small fibers with tailored

Nature has engineered universal, catechol-containing adhesives which can be synthetically mimicked in the form of polydopamine (PDA). In this study, PDA was exploited to enable the formation of block copolymer (BCP) nanopatterns on a variety of soft material surfaces. While conventional PDA coating times (1 h) produce a layer too rough for most applications of BCP nanopatterning, we found that these substrates could be polished by bath sonication in a weakly basic solution to form a conformal, smooth (root-mean-square roughness ∼0.4 nm), and thin (3 nm) layer free of large prominent granules. This chemically functionalized, biomimetic layer served as a reactive platform for subsequently grafting a surface neutral layer of poly(styrene-random-methyl methacrylate-random-glycidyl methacrylate) to perpendicularly orient lamellae-forming poly(styrene-block-methyl methacrylate) BCP. Moreover, scanning electron microscopy observations confirmed that a BCP nanopattern on a poly(ethylene terephthalate) substrate was not affected by bending with a radius of ∼0.5 cm. This procedure enables nondestructive, plasma-free surface modification of chemically inert, low-surface energy soft materials, thus overcoming many current chemical and physical limitations that may impede high-throughput, roll-to-roll nanomanufacturing.

In nanoconfined thin films, numerous studies have revealed the thickness dependencies of different thermophysical properties, including the glass transition temperature (T g) and self-diffusion coefficient (D). While quantitative relationships between these properties are well-known for bulk polymers, analogous relationships for nanoconfined polymers are still not clear. Herein, T g−D relationships are studied under nanoconfinement using spectroscopic ellipsometry for measuring T g and fluorescence recovery after photobleaching for measuring D. Poly­(isobutyl methacrylate) (PiBMA) was selected as a model unentangled polymer, and it was nanoconfined to 14–300 nm thick films. Multilayered geometries incorporating PiBMA were constructed to systematically study the influence of free surfaces (i.e., polymer surfaces exposed directly to air, also called uncapped) and surfaces that were in contact with a secondary polymer (also called capped). This multilayer approach additionally allowed investigation of both relatively weak and strong interactions between the polymer and substrate, depending on the existence of hydrogen bonding. The T g–D relationship observed in nanoconfined thin films deviated from that in the bulk state (e.g., as described by Williams–Landel–Ferry and Stokes–Einstein, or similar relationships). A model was employed that considered the effects of molecular friction between the different confining interfaces and PiBMA, and it successfully described the deviation from bulk behavior.

We demonstrate that deep learning techniques can be used to predict motility-induced phase separation (MIPS) in suspensions of active Brownian particles (ABPs) by creating a notion of phase at the...