Strategies for the Synthesis of Well-Defined Star Polymers by Anionic Polymerization with Chlorosilane Coupling and Preservation of the Star Architecture during Catalytic Hydrogenation

Investigation of eight-arm tapered star copolymers prepared by anionic copolymerization and coupling reaction

A series of eight-arm tapered star copolymers 8[P(I-co-S)x]-POSS were synthesized by the coupling reaction between octavinyl POSS and the tapered living copolymer chains obtained from statistical anionic copolymerization.

Molecular and Structure-Properties Comparison of an Anionically Synthesized Diblock Copolymer of the PS-b-PI Sequence and Its Hydrogenated or Sulfonated Derivatives

An approach to obtaining various nanostructures utilizing a well-studied polystyrene-b-poly(isoprene) or PS-b-PI diblock copolymer system through chemical modification reactions is reported. The complete hydrogenation and partial sulfonation to the susceptible carbon double bonds of the PI segment led to the preparation of [polystyrene-b-poly(ethylene-alt-propylene)] as well as [polystyrene-b-poly(sulfonated isoprene-co-isoprene)], respectively. The hydrogenation of the polyisoprene block results in enhanced segmental immiscibility, whereas the relative sulfonation induces an amphiphilic character in the final modified material. The successful synthesis of the pristine diblock copolymer through anionic polymerization and the relative chemical modification reactions were verified using several molecular and structural characterization techniques. The thin film structure–properties relationship was investigated using atomic force microscopy under various conditions such as different solvents and annealing temperatures. Small-angle X-ray scattering was employed to identify the different observed nanostructures and their evolution upon thermal annealing.

“Core-first” approach for the synthesis of star-shaped polyisoprenes with a branched core and isoprene catalyzed by half-sandwich scandium complexes

Star-shaped polyisoprenes were synthesized by copolymerization of isoprene and branched homopolymer of dimethyl-di-2,4-pentadienyl-(E, E)-silane through “Core-first” approach catalyzed by half-sandwich scandium complex.

Rapid one-pot synthesis of tapered star copolymers via ultra-fast coupling of polystyryllithium chain ends

Efficient coupling of sterically demanding polystyryllithium (PS-Li) chain ends is achieved using tetra[3-(chloro-dimethylsilyl)propyl]silane (TCDMSPS) as a linking agent. This general approach is employed for the rapid synthesis of tapered star copolymers.

Reversible star assembly of polyolefins using interconversion between boroxine and boronic acid

The reversible star formation of polyolefins, with boronic acid modified chain-ends, was achieved.

Effect of long-range interactions on nanoparticle-induced aggregation

The process of attaching liquid media molecules to dispersed nanoparticles is studied by numerically investigating the time evolution of the size distribution of the emerging aggregates. Within the considered mechanism of aggregation, both the primary particles and the resulting aggregates are assumed to connect freely dispersing molecules, but the particles and aggregates are not allowed to self-link or self-assemble at each evolution stage of the system, due to, e.g., repulsive interactions. The process of random attachment of dispersing molecules to immersed nanoparticles and aggregates is considered to be driven by attractive long-range interactions of the van der Waals type. The molecule binding rate is, in consequence, modeled as being dependent not only on the size and surface morphology of the existing aggregates, but also on the van der Waals forces, whose strength is itself treated as dependent on the aggregate size. It is demonstrated that these forces diminish, in general, the inhomogeneity of aggregate size. Such an effect is shown to be especially distinct when the interaction strength is relatively large but does not increase as aggregates increase in size, i.e., when strongly attracted media molecules functionalize the resultant aggregates to prevent the increase of the interaction strength. This result can be helpful to construct stable complex substances containing aggregates with low size dispersion. Surprisingly, the evolution of aggregating systems toward more significant inhomogeneity takes place when the interaction strength is initially large and increases fast enough with the size of aggregates.