Brush‐First Synthesis of Core‐Photodegradable Miktoarm Star Polymers via ROMP: Towards Photoresponsive Self‐Assemblies. Issue 2 (22nd November 2013)

• Record Type: Journal Article
• Authors: Burts, Alan O.; Gao, Angela X.; Johnson, Jeremiah A.; Lutz, J.‐F.; Sumerlin, B.; Matyjaszewski, K.
• Is Part Of: Macromolecular rapid communications. Volume 35:Issue 2(2014:Jan.)
• Page Start: 168
• Page End: 173
• Publication Date: 2013-11-22
• Subjects: Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.201300618
• Languages: English
• ISSNs: 1022-1336

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>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)‐<italic>branch</italic>‐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<italic>‐branch‐</italic>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. <boxed-text content-type="graphic" position="anchor" orientation="portrait"><graphic position="anchor" mimetype="image" xlink:href="ark:/27927/pgg40bbgjqm" orientation="portrait" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></boxed-text></p> </abstract>