Wu, Gang, et al. Current Applied Physics 11.3 (2011): 321-326.
Challenge: Developing microcapsules for electrophoretic displays requires ultra-thin yet robust walls to ensure optical clarity and prevent core leakage. Conventional coacervation methods struggle to achieve sub-micron wall thickness while maintaining structural integrity during thermal cycling.
Solution: Sodium Laurylsulfonate (SLS) was engineered as a molecular mediator in gelatin/odium carboxymethylcellulose (NaCMC) microcapsules. At precisely 1.0 mM concentration (below critical micellar concentration), SLS catalyzed polymer complexation via enhanced electrostatic bridging, enabled uniform wall knitting through pH-triggered self-assembly, facilitated 200nm ultra-thin wall formation.
Synthesis: Microcapsule synthesis involved dispersing tetrachloroethylene core in NaCMC solution (45°C), adding SLS-enhanced gelatin solution under precise pH control, inducing coacervation via acetic acid titration (pH 5.0 → 4.2), and thermally cycling to 10°C with glutaraldehyde crosslinking.
Key Results:
· Stable, elastic and optically transparent GE/NaCMC/SLS microcapsules with ultrathin capsule wall thickness of 200nm and tetrachloroethylene as the core were successfully prepared.
· SLS regulates capsule formation by adjusting the amount of NaCMC adsorbed at the water/oil interface.
· Excessive SLS will cause defects in the microcapsule wall, and when the SLS concentration is higher than 2.0 mM, stable microcapsules cannot be formed.