Influence of interfacial compatibility on the crystallization behavior of electrospun core–sheath fibers

Core–sheath fibers composed of a crystalline polymer [poly(ethylene oxide) (PEO)] in the core and amorphous polymers [polystyrene (PS) and poly(methyl methacrylate) (PMMA)] in the sheath were fabricated through coaxial electrospinning. Because the melting temperature of PEO is lower than the glass transition temperatures of PS and PMMA, PEO crystallization was hard-confined within the immobile sheath. In immiscible PEO/PS fibers and miscible PEO/PMMA fibers, hard confinement reduced the crystallizability of PEO; therefore, its crystallite size, degree of crystallinity, and crystallization kinetics decreased with decreases in the degree of confinement. Confinement hindered PEO crystallization to a greater extent when the core and sheath polymers were miscible than when they were not. The favorable interaction between PEO and PMMA facilitated their interdiffusion during electrospinning, which caused the increased confinement of PEO in the core. Furthermore, when the compatibility between the solvents used for coaxial electrospinning increased, they enhanced the interdiffusion of the core and sheath polymers, which hindered PEO crystallization. However, the compatibility between polymers influenced the crystallization behavior of PEO to a considerably greater extent than did the compatibility between solvents.