Nanodroplet formation and exclusive homogenously nucleated crystallization in confined electrospun immiscible polymer blend fibers of polystyrene and poly (ethylene oxide)

In electrospun PEO/PS (30/70) blend fibers, when annealing temperature is below 95°C, the majority crystallizes heterogeneously at around 40°C; when annealing temperature is above 125°C, fibers break into numerous nanodroplets and homogeneous/surface-induced nucleation at large undercooling dominates due to lack of heterogeneities.

“When the annealing temperature is below 95 °C, the temperature is not enough to break the largest part of the electrospun fibers, therefore, the majority of PEO/PS blend will crystallize heterogeneously at around 40 °C ( Fig. 10 A).However, when the annealing temperature is above 125 °C, PEO/PS blend fibers break into numerous nanodroplets and homogeneous/surface-induced nucleation at large under”

In PEO/PS nanofibers, neat PEO has Avrami index around 3 at 53°C indicating 3-D unconfined crystal growth after instantaneous nucleation; annealing at 85°C and crystallizing at 48°C gives Avrami index 2.1, revealing 2-D confined crystal growth after instantaneous nucleation; annealing at 150°C gives Avrami index around 1 at 0 or -10°C, confirming homogeneous or surface-induced nucleation.

“As a comparison, the crystallization kinetics of neat PEO was also studied, and the Avrami index around 3 at 53 °C indicates a 3-D unconfined crystal growth after instantaneous nucleation.When P4tBS coated PEO/PS fibers were annealed at 85 °C and then cooled down to crystallize at 48 °C (near the higher fractionated T c ), the Avrami index decreased to 2.1, revealing a 2-D confined crystal growth”