Growing Polymer Crystalsomes under Dynamic Confinement

PART 1: NON-TECHNICAL SUMMARY

Polymer nanoparticles (PNPs) can bring many benefits and have been widely used in various applications including electronics, photonics, biomedicine, food science, cosmetics, and additive manufacturing. Extensive work has been devoted to controlling PNP formation using emulsion polymerization, controlled precipitation, liquid/liquid phase separation and templated self-assembly.

Polymer crystalsomes, as a class of newly discovered PNPs, refer to hollow nanoparticles where the particle shells are formed by polymer single crystals. Compared to conventional PNPs, polymer crystalsomes show excellent mechanical and unique thermal properties and offer facile control over their size, shape, and chemical composition. Hollow polymersomes with sizes ranging from ~ 100 nm to microns can be readily fabricated.

This project aims to systematically investigate the formation process of these newly developed polymer crystalsomes by using three model emulsion systems. Knowledge achieved through this project will help to understand crystalsome growth and enable the fabrication of complex PNPs for current and new applications. This project also offers opportunities for mentoring undergraduate and graduate students and developing new course modules. The results will strengthen various outreach activities such as summer materials science camps.

PART 2: TECHNICAL SUMMARY

Polymer crystalsomes are a class of hollow PNPs with single crystal shells, and they are typically grown using a nanoemulsion-solution crystallization system. While a series of polymer crystalsomes have been successfully grown using homopolymers and block copolymers, understanding the formation process remains elusive. This lack of clarity exists because the nanoemulsion-based crystalsome growth is complex, including interwoven processes such as emulsification, liquid/liquid phase separation, and polymer crystallization.

The proposed work will be undertaken to systematically investigate the formation process of crystalsomes. To establish a detailed understanding of the crystallization process in nanoemulsions, this project will develop a new scientific framework of dynamic confinement in polymer crystallization, in which polymer diffusion into and out of the crystallization system is allowed and controlled to program the crystallization process in nanoemulsions.

Three model emulsion systems, including oil-in-water (O/W) nanoemulsions, water-in-oil (W/O) nanoemulsions, and quiescent nanoprecipitation (“Ouzo emulsions”), will be employed in this study. These complementary systems will be used to tune the dynamic confinement and polymer phase separation process in the system. Furthermore, a library of complex polymer crystalsomes will be fabricated with controlled characteristics, such as size, opening, curvature, and function.

The project, therefore, will advance our fundamental understanding of polymer crystallization under dynamic confinement.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.