ma9b02295_si_002.zip (37.73 MB)
Nucleation of Poly(lactide) Partially Wet Droplets in Ternary Blends with Poly(butylene succinate) and Poly(ε-caprolactone)
dataset
posted on 2020-02-25, 02:13 authored by Seif Eddine Fenni, Jun Wang, Nacerddine Haddaoui, Basil D. Favis, Alejandro J. Müller, Dario CavalloThis work presents the first investigation
on the crystallization
behavior of partially wet droplets in immiscible ternary blends. Poly(lactide),
poly(ε-caprolactone), and poly(butylene succinate) (PLA, PCL,
and PBS, respectively) were melt blended in a 10/45/45 weight ratio
to produce a “partial wetting” morphology with droplets
of the PLA minor phase located at the interface between the other
two major components. The crystallization process of the higher melting
PLA droplets was studied by polarized light optical microscopy, while
the other components remain in the molten state. We found that neighboring
partially wet droplets nucleate in close sequence. This is unexpected
since partially wet droplets display points of three-phase contact
and, hence, should not touch each other. Moreover, the onset of poly(lactide)
crystallization is frequently observed at the interface with molten
PCL or PBS, with a significant preference for the former polymer.
The observed sequential droplet-to-droplet crystallization is attributed
to the weak partial wetting behavior of the PCL/PLA/PBS ternary system.
In fact, the contact between the interfacially confined droplets during
crystallization due to their mobility can lead to a transition from
a partial to a completely wet state, with the formation of thin continuous
layers bridging larger partially wet droplets. This allows crystallization
to spread sequentially between neighboring domains. Using a simple
heterogeneous nucleation model, it is shown that the nucleation of
PLA on either PCL or PBS melts is energetically feasible. This study
establishes a clear relationship between the unique partial wetting
morphology of ternary blends and the nucleation of the minor component,
paving the way to the understanding and control of crystallization
in multiphasic polymer blends for advanced applications.