Synthesis of star polymers via nitroxide mediated free-radical polymerization: A “core-first” approach using resorcinarene-based alkoxyamine initiators

Successful synthesis of distinct dendritic unimolecular initiators suitable for topologically attractive star polymers

Synthesis of two types of dendritic unimolecular initiators containing an initiator number functionality of up to 48 has been described and their efficiency in the synthesis of multiarm star polymers has been confirmed.

Influence of a resorcin[4]arene core structure on the spatial directionality of multi-arm poly(ε-caprolactone)s

The spatial directionality of polymer chains in multi-arm polymers can be used to manipulate their thermal and physical properties. Synthesis of directional poly(ε-caprolactone), based on a rigid and flexible resorcin[4]arene initiator core, was accomplished via ring-opening polymerization catalyzed by Sn(Oct)₂ in bulk at 120 °C.

Synthesis of multi-block copolymer stars using a simple iterative Cu(0)-mediated radical polymerization technique

A new iterative copper(0)-mediated radical polymerization approach is presented that represents a significant advance in the synthesis of high order multi-block star copolymers. The synthesis of these materials can now be achieved in high yield and with controlled structural complexity, with purification only required at the last step. The approach is general, facile and offers the opportunity to synthesize new copolymer stars.

Nitroxides: applications in synthesis and in polymer chemistry

This Review describes the application of nitroxides to synthesis and polymer chemistry. The synthesis and physical properties of nitroxides are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis. The oxidation of alcohols and carbanions, as well as oxidative C-C bond-forming reactions are presented along with other typical oxidative transformations. A section is also dedicated to the extensive use of nitroxides as trapping reagents for C-centered radicals in radical chemistry. Alkoxyamines derived from nitroxides are shown to be highly useful precursors of C-centered radicals in synthesis and also in polymer chemistry. The last section discusses the basics of nitroxide-mediated radical polymerization (NMP) and also highlights new developments in the synthesis of complex polymer architectures.

Shielding effects in polymer-polymer reactions. IV. Intermolecular contact formation between star-branched molecules

Pairs of star-branched molecules--taken from ensembles of athermal five-way cubic lattice chains prepared by Monte Carlo simulation--are analyzed for the relative probability of mutual contact formation between particularly specified segments i and j belonging to different chains within these pairs. These contact probabilities--termed shielding factors K(ij)--are calculated by means of exact enumeration as a function of chain length ranging from n = 8 to 256 bonds per arm, as a function of functionality (i.e., the number of arms) ranging from F = 2 to 6 arms, and as a function of segment position within the arms ranging from central to terminal segments. In addition, changes of properties that characterize the size and shape of the involved molecules while approaching and penetration are evaluated as a function of chain separation.