Polymer Chemistry Blog

In this study, van Hest and co-workers demonstrated that nanometer-sized polymersomes assembled from two dissimilar diblock copolymers can undergo shape changes, driven by strong lateral polymer/polymer segregation within the membrane. The two particular block copolymers consisted of identical hydrophobic fragments to stimulate co-assembly, while their hydrophilic segments were either neutrally or negatively charged. It was hypothesized that demixing of the two types of polymer amphiphiles within the bilayer was caused by the different hydrophilic polymer fractions exhibiting intrinsically different interfacial curvatures upon self-assembly. Given the potentially unlimited number of possible hybrid polymersome systems, the local polymer/polymer separation phenomenon could be easily exploited further in the construction of new polymersome morphologies, with potential applications in both nanoscience and biomedical fields.

Spontaneous shape changes in polymersomes via polymer/polymer segregation by Silvie A. Meeuwissen, Stéphanie M. C. Bruekers, Yingchao Chen, Darrin J. Pochan and Jan C. M. van Hest Polym. Chem. 2014, 5, 489-501.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, Crespy and co-workers developed an easy, low-cost and mild strategy to fabricate PPs in large quantities without using block copolymers. Polymerization-induced phase separation was found to be the reason for the formation of the PPs. The size of the patches could be easily tuned by controlling the monomer conversion or by changing the composition of the nanoparticles. The atomic force microscopy analysis revealed that the patches were sticky and embedded in a harder polymer matrix. Moreover, the patchy structure could be locked by cross-linking the sticky patches. Their approach could be extended to prepare large libraries of different PPs by choosing other polymer/monomer pairs and/or by post-functionalizing the patchy area.

Polymer patchy colloids with sticky patches by Yi Zhao, Rüdiger Berger, Katharina Landfester and Daniel Crespy Polym. Chem. 2014, 5, 365-371.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, Leibler and co-workers reported on the subtle influence of solvent on the organization of supramolecular polymers. They synthesized homotelechelic and heterotelechelic oligomers of poly(propylene oxide) (PPO) equipped with complementary hydrogen bonding functional ends, thymine (Thy) and diaminotriazine (DAT). In a solvent that dissociates Thy–DAT hydrogen bonds, such as DMSO, the viscosity was low for all functional telechelic oligomers. In non-dissociative solvents, the addition of functional oligomers increased the viscosity. For both the homotelechelic blends and the heterotelechelics, the viscosity in toluene was about two times higher than that in chloroform. Additionally, the Thy–DAT association constant was 22 times higher. Carbon relaxation times measured by NMR and viscosity variation for solutions of different concentrations suggest a distinct supramolecular organization in chloroform and toluene: linear and cyclic supramolecular chains in chloroform and small π-stacked objects with a PPO shell and a Thy, DAT core in toluene. One might expect that when the materials are obtained by solvent evaporation, the organization in the bulk is solvent dependent as this is often the case for ABC block copolymers.

Binding and supramolecular organization of homo- and heterotelechelic oligomers in solutions by Jessalyn Cortese, Corinne Soulié-Ziakovic and Ludwik Leibler Polym. Chem. 2014, 5, 116-125.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.