Micropattern Fabricated by Acropetal Migration Controlled through Sequential Photo and Thermal Polymerization.

Bottom-up patterning technology plays a significant role in both nature and synthetic materials, owing to its inherent advantages such as ease of implementation, spontaneity, and noncontact attributes, etc. However, constrained by the uncontrollability of molecular movement, energy interaction, and stress, obtained micropatterns tend to exhibit an inevitable arched outline, resulting in the limitation of applicability. Herein, inspired by auxin's action mode in apical dominance, a versatile strategy is proposed for fabricating precision self-organizing micropatterns with impressive height based on polymerization-induced acropetal migration. The copolymer containing fluorocarbon chains (low surface energy) and tertiary amine (coinitiator) is designed to self-assemble on the surface of the photo-curing system. The selective exposure under a photomask establishes a photocuring boundary and the radicals would be generated on the surface, which is pivotal in generating a vertical concentration difference of monomer. Subsequent heating treatment activates the material continuously transfers from the unexposed area to the exposed area and is accompanied by the obviously vertical upward mass transfer, resulting in the manufacture of a rectilinear profile micropattern. This strategy significantly broadens the applicability of self-organizing patterns, offering the potential to mitigate the complexity and time-consuming limitations associated with top-down methods.

Photochemical Design for Diverse Controllable Patterns in Self-Wrinkling Films.

Harnessing the spontaneous surface instability of pliable substances to create intricate, well-ordered, and on-demand controlled surface patterns holds great potential for advancing applications in optical, electrical, and biological processes. However, the current limitations stem from challenges in modulating multidirectional stress fields and diverse boundary environments. Herein, this work proposes a universal strategy to achieve arbitrarily controllable wrinkle patterns via the spatiotemporal photochemical boundaries. Utilizing constraints and inductive effects of the photochemical boundaries, the multiple coupling relationship is accomplished among the light fields, stress fields, and morphology of wrinkles in photosensitive polyurethane (PSPU) film. Moreover, employing sequential light-irradiation with photomask enables the attainment of a diverse array of controllable patterns, ranging from highly ordered 2D patterns to periodic or intricate designs. The fundamental mechanics of underlying buckling and the formation of surface features are comprehensively elucidated through theoretical stimulation and finite element analysis. The results reveal the evolution laws of wrinkles under photochemical boundaries and represent a new effective toolkit for fabricating intricate and captivating patterns in single-layer films.

Anode-Free Lithium Metal Batteries Based on an Ultrathin and Respirable Interphase Layer.

Anode-free lithium (Li) metal batteries are desirable candidates in pursuit of high-energy-density batteries. However, their poor cycling performances originated from the unsatisfactory reversibility of Li plating/stripping remains a grand challenge. Here we show a facile and scalable approach to produce high-performing anode-free Li metal batteries using a bioinspired and ultrathin (250 nm) interphase layer comprised of triethylamine germanate. The derived tertiary amine and Lix Ge alloy showed enhanced adsorption energy that significantly promoted Li-ion adsorption, nucleation and deposition, contributing to a reversible expansion/shrinkage process upon Li plating/stripping. Impressive Li plating/stripping Coulombic efficiencies (CEs) of ≈99.3 % were achieved for 250 cycles in Li/Cu cells. In addition, the anode-free LiFePO4 full batteries demonstrated maximal energy and power densities of 527 Wh kg-1 and 1554 W kg-1 , respectively, and remarkable cycling stability (over 250 cycles with an average CE of 99.4 %) at a practical areal capacity of ≈3 mAh cm-2 , the highest among state-of-the-art anode-free LiFePO4 batteries. Our ultrathin and respirable interphase layer presents a promising way to fully unlock large-scale production of anode-free batteries.

Photo-induced spatial gradient network for shape memory polymer with pattern-memorizing surface.

Incorporating a pattern-memorizing surface into a multi-functional shape memory polymer (SMP) offers various extraordinary opportunities for their engineering applications. However, current memory-patterned approaches prepared by artificial loading are at the cost of initial balance, whose potential is greatly limited by the internal relationship between thermodynamic equilibrium and the entropy-driven pattern-memorizing cycle. Here, a robust yet effective strategy is presented for fabricating a spontaneous pattern on a poly(styrene-block-butadiene-block-styrene) (SBS)-based SMP with a gradient crosslinking network via molecular diffusion for equilibrium. Benefiting from the photo-induced diffusion of maleimide, the resulting steady-state pattern as a permanent shape ensures the recovery of morphology, and the gradient network formed by the diffusion-regulated spatial Diels-Alder (D-A) crosslinking reaction makes the pattern memory cycle from existence to elimination possible. Furthermore, taking advantage of an uneven structural network, the shape reconfigurations from 2D patterned sheets to 3D configurations with a patterned surface can be achieved conveniently through a shape memory effect, simplifying programming setups. In addition, this type of 3D shape also can shift back to a 2D patterned film via an inverse D-A decrosslinking reaction upon thermal treatment. This straightforward approach for fabricating a pattern of a single layer on an SMP surface with a spatial gradient network opens a new avenue for functional smart materials, which expands the technological perspectives in many fields of flexible electronics, smart actuators, switching sensors and soft robotics.

Stress Communication between the Chain Movement and the Shape Transformation from 2D to 3D.

Shape memory polymers can change their initial shape under the stimulation of the external environment, but most of the stimulations require not only an external force but also a high temperature, which limits their application to a certain extent. Inspired by the unmatched elongation of cells on both sides of the mimosa petiole in nature, which leads to leaf closure, we designed a new type of shape transformation polymer, which can transform between 2D and 3D by simple stretching and releasing steps at room temperature. Surface patterning on one side of the sample film was realized via a coordination network of Fe3+-COOH to achieve different coordination gradients along its thickness. By this way, different movements of polymer chains along the thickness would lead to 2D-3D transformation upon releasing the stretched sample. Using this method, we obtained a series of transformations from customized 2D materials to complex 3D shapes and explored their potential application in information encryption transmission.