Assembly of Short-Chain Amphiphilic Homopolymers into Well-Defined Particles.

Linear homopolymers of norbornene (NBE) derivatives equipped with short-chain alcohol pendant groups were prepared by ring-opening metathesis polymerization (ROMP) and subsequently assembled into well-defined structures in alcohol solvents. The ratios of hydrophobic carbons and hydrophilic alcohol groups at the repeating monomeric unit in these short-chain amphiphilic polymers were found to play an important role in determining the size and distribution of the final globular structures. Unlike the assembly of other linear homo- and copolymers possessing long-chain amphiphilicity, NBE-based linear polymers were readily transformed into spherical particles with a layered conformation, whose sizes range from a few hundred nanometers to micrometers with narrow distributions, simply by controlling the concentration and molecular weights of the linear homopolymers without using any surfactants. In addition, the degree of the intermolecular forces with solvents (e.g., solvation) possessing different surface tensions and polarities highly affected the final diameter and distribution of the polymer particles, implying the importance of the selection of a proper solvent to regulate their structural features. As such, understanding the assembly of these types of short-chain homopolymers into uniform particles can allow for regulating the transformation of diverse linear amphiphilic polymers into precisely controlled structures for various applications.