Tunable Multilobe Particle Geometry by Annealing-Assisted Emulsion Polymerization


The synthesis of nonspherical polymer particles is generally challenging compared to that of spherical counterparts due to higher surface area and potential associated free-energy penalty. Here, multilobed composite polymer particles were synthesized through two-stage seeded emulsion polymerization by restricting or enabling second-stage polymer rearrangement on the surface of the seed particles. The investigation focuses on morphologies at in situ pseudo-equilibrium states toward the control of the number and shape of the lobes (patches) on seeds of different-sized scales (180, 500, 800 nm). To achieve those states, a postannealing process was found to be a critical step for reducing the number and increasing the size and spacing of the lobes on the seeds. Snowman, dumbbell, trigonal planar, and tetrahedral geometries were all individually realized. Tuning to a specific primary particle geometry is important for potential assembly applications into targeted porous suprastructures such as tissue engineering scaffolds. Interfacial free energies at all polymer and water interfaces were calculated for each geometry to rationalize the observations. Additionally, the relevant polymer diffusion coefficient during annealing was used to predict the surface diffusion time for the lobe polymer chains to rearrange for a given seed size to achieve a desired nonspherical multilobed morphology with a target number of lobes.

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ACS Applied Polymer Materials


ACS Publications

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