As electronics become smaller and denser in function, lighter polymer composites with high thermal conductivity (TC) have been increasingly developed as heat-dissipating materials. Since the polymer matrix exhibits a vanishingly low TC compared with that of the filler, the composite TC is determined by the heat conduction pathway formed along the interconnected filler networks. In this context, a high composite TC can be obtained by increasing the filler loading up to the maximum filler packing limit. However, a tradeoff between the composite weight and TC prohibits a constant increase in the filler loading. To this end, a highly networked but heat-processable poly­(β-amino ester) covalent adaptable network (CAN) based on catalyst-free transesterification and a dynamic aza-Michael reaction is synthesized as a matrix to realize both a high composite TC and low density. Owing to the unique malleable characteristic of the CAN, conductive filler networks (or a segregated filler structure) are formed along the CAN domain interfaces upon simple heat-pressing a powder mixture of the CAN and hexagonal boron nitride (hBN). The resulting composite exhibits an exceptionally high TC of 13.5 W/mK at a low density of 1.75 g/cm3. The TC value corresponds to 197% of an identical CAN composite but with randomly dispersed hBN. To further highlight the versatility of the CAN matrix, ecofriendly composite recycling through reprocessing along with filler recovery by depolymerizing the matrix in heated water without using any external catalysts is also demonstrated.

The Marangoni effect causes liquids to flow toward localized regions with higher surface tension. In a polymer thin film, the flow induced by photochemically programmed surface tension gradients can be harnessed to manufacture patterned surfaces. Patterned polymer films are particularly useful for controlling adhesion, improving photonic device efficiency, and directing cellular alignment. In general, a broader range of accessible pattern resolutions and/or aspect ratios ensures a broader range of applications. However, because of the process flow for pattern formation, the final pattern periodicity of the Marangoni‐driven features matches that of the initially prescribed surface energy pattern. To achieve better resolution without using sophisticated and complex tools, a shrinking (or pre‐strained) polymer film is used as a substrate. The shrinking substrate can “contract or densify” the features along the substrate plane. Consequently, the resolution of the patterns formed on the shrinking substrate is improved by the shrinkage rate of the substrate compared with those formed on the non‐shrinking substrate (i.e., silicon wafer).