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Breakups of Chitosan microcapsules in extensional flow
Revaz Chachanidze1, Kaili Xie2, Jinming Lyu3
1Univ. Grenoble Alpes, CNRS, Grenoble INP, LRP, Grenoble, France.
Journal of Colloid and Interface Science
|September 10, 2022
Summary
Controlled capsule rupture is key for material release. We studied chitosan/PFacid shells in extensional flow, finding rupture depends on shell properties and stress, revealing solid-like and liquid-like breakup regimes.
Area of Science:
- Materials Science
- Rheology
- Chemical Engineering
Background:
- Controlled rupture of core-shell capsules is crucial for targeted material delivery.
- The mechanical properties of capsule shells dictate their behavior under stress.
- Understanding rupture dynamics is essential for designing effective carrier systems.
Purpose of the Study:
- To investigate the rupture mechanisms of weakly cohesive chitosan/PFacid shells under planar extensional flow.
- To establish the relationship between shell mechanical properties, hydrodynamic stress, and rupture dynamics.
- To identify different rupture regimes based on shell complexation time and applied stress.
Main Methods:
- Fabrication of core-shell capsules using interfacial complexation of Chitosan and PFacid.
- Application of planar extensional flow to induce controlled rupture.
- Observation of rupture dynamics using two observational planes and fluorescent labeling.
- Numerical determination of internal stress to identify rupture initiation points.
Main Results:
- Three distinct rupture regimes were observed based on hydrodynamic stress and shell complexation time.
- At low complexation times (weak shells), rupture resembles droplet breakup (dumbbell/waist) due to continuous thinning, suggesting a solid-to-liquid transition.
- At longer complexation times (stronger shells), rupture exhibits solid-like breakage with membrane discontinuity, initiated at points of maximal internal constraint.
- Increased elongation rates lead to more complex rupture patterns with multiple break points.
Conclusions:
- The rupture behavior of chitosan/PFacid capsules is highly dependent on the interplay between shell mechanical properties (shear elastic modulus) and applied hydrodynamic stress.
- A phase diagram illustrating these dependencies was established, differentiating between liquid-like and solid-like rupture modes.
- The findings provide critical insights for designing and controlling the release of encapsulated materials from soft carriers.
