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  • Brush-first synthesis of core-photodegradable miktoarm star polymers via ROMP: towards photoresponsive self-assemblies.

Brush-first synthesis of core-photodegradable miktoarm star polymers via ROMP: towards photoresponsive self-assemblies.

Macromolecular rapid communications (2013-11-23)
Alan O Burts, Angela X Gao, Jeremiah A Johnson
ABSTRACT

This report describes the synthesis of miktoarm brush-arm star polymers (BASPs) from branched and linear norbornene-terminated macromonomers (MMs) via the brush-first ring-opening metathesis polymerization (ROMP) method. First, a polystyrene (PS)-branch-poly(lactic acid) (PLA) MM is synthesized via a combination of atom transfer radical polymerization (ATRP), tin(II)-mediated ring opening polymerization, and copper-catalyzed azide-alkyne cycloaddition reactions. Graft-through ROMP of this MM followed by in situ cross-linking with a photo-cleavable bis-norbornene derivative provided nanoscopic BASPs with photodegradable cores and a precise 1:1 PS:PLA arm composition. Three-miktoarm BASPs are prepared in an analogous manner via copolymerization of the same PS-branch-PLA MM with a poly(ethylene glycol) (PEG) MM prior to cross-linking. Intramolecular phase segregation of these miktoarm BASPs is characterized by transmission electron microscopy (TEM); a UV-induced structural rearrangement from three-faced Janus particles to micelles is observed.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
O-(2-Aminoethyl)polyethylene glycol 3,000, Mp 3,000