title: Self-assembly of pH-sensitive random copolymers: poly(styrene-co-4-vinylpyridine).
abstract: A series of pH-sensitive random copolymers, poly(styrene-co-4-vinylpyridine) (PSVP), with molecular weight about 10,000 and 4-vinylpyridine molar contents of 19-53%, were conveniently synthesized by free radical polymerization. The copolymers experience the formation, swell, and dissociation of multichain nanoparticles when the pH of the aqueous solutions/dispersions changes from 5.1 to 1.0. The nanoparticles have hydrodynamic diameters around 100 nm, a spherical shape, and a relatively uniform structure in a pH range of about 5-3 and a multicore structure at lower pH. The random distribution of the building units causes some of the hydrophilic units, protonated 4-vinylpyridine groups, to be trapped inside the nanoparticles. So the hydrophobicity of the nanoparticles is tunable by changing the 4-vinylpyridine content in the copolymers. For the copolymers with higher 4-vinylpyridine molar content, the pH range in which the multichain nanoparticles form shifts to higher values, the multichain nanoparticles dissociate, and the copolymers form single-chain hydrophobic domains at low pH.
authors.affiliation: The Key Laboratory of Molecular Engineering of Polymer and Department of Macromolecular Science, Fudan University, Shanghai 200433, China.
authors.forename: Peide
authors.initials: P
authors.lastname: Guo
authors.forename: Wenyan
authors.initials: W
authors.lastname: Guan
authors.forename: Li
authors.initials: L
authors.lastname: Liang
authors.forename: Ping
authors.initials: P
authors.lastname: Yao