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Polymers are thermally insulating due to randomly oriented molecular chains, limiting their effectiveness in thermal management. However, when processed into nanofibers, polymers can exhibit significantly higher thermal conductivity, primarily due to enhanced internal structures such as crystallinity and molecular alignment. Characterizing these structural parameters at the single nanofiber level remains a challenge, limiting understanding of thermal transport mechanisms. Here, we investigate the relationship between internal structure and thermal conductivity of single polyethylene oxide (PEO) nanofibers fabricated from near-field electrospinning (NFES). By varying molecular weight and concentration of PEO, their impact on thermal conductivity and internal structure are examined. Crystallinity is examined using conventional Raman spectroscopy, while molecular orientation is assessed through polarized Raman and polarized FTIR spectroscopy. Results reveal that enhanced thermal conductivity in PEO nanofibers is primarily attributed to increased molecular orientation. A maximum thermal conductivity of 2.7 W/m·K is achieved in PEO nanofibers, representing a notable improvement over bulk PEO (0.2 W/m·K). These findings demonstrate the potential of structurally engineered PEO nanofibers for thermal applications including electronic packaging and thermal interface materials. Further, the approach presented in this work can provide a framework for exploring thermal transport mechanisms in other polymer systems. 

Polymer porous membranes are crucial in various applications, including water filtration, tissue engineering, and drug administration. Conventional far‐field electrospinning (FFES) is widely used for producing polymeric membranes due to its cost‐effectiveness, scalability, and flexibility in using many polymers. However, FFES has limitations in controlling pore form and size, as it produces randomly oriented fibers that lead to inconsistent and noncustomizable pore sizes. To address these limitations, this work combines near‐field electrospinning (NFES) with thermal treatment of polymer fibers and membranes. NFES offers more precise control over fiber placement and alignment, producing well‐defined fiber patterns with consistent and customizable pore sizes without compromising the thickness of membranes. By exploring the interplay between polymer behavior, thermal effects, and capillary action, the differences in pore area under various temperatures and fiber spacings are characterized. Additionally, this study investigates the influence of multilayer infusion on pore size and geometric arrangement by examining multilayer configurations stacked at various angles. The results indicate that increasing the number of layers leads to decreased pore size, while the alignment of infused fibers affects pore shape. This integrated approach enhances control over membrane characteristics, improving the performance and consistency of polymer porous membrane fabrication across various applications.