Star Block Copolymers Through Nitroxide‐Mediated Radical Polymerization From Polyhedral Oligomeric Silsesquioxane (POSS) Core

Abstract

A series of star block copolymers were prepared through nitroxide‐mediated radical polymerization (NMRP) from polyhedral oligomeric silsesquioxanes (POSS) nanoparticle by core‐first polymerization. Eight N‐alkoxyamine groups were incorporated onto the eight corners of a POSS cube through quantitative hydrosilylation through addition of octakis(dimethylsiloxy)silsesquioxane (Q8M POSS) with 1‐(2‐(allyloxy)‐1‐phenylethoxy)‐2,2,6,6‐tetramethylpiperidine (allyl‐TEMPO) and Karstedt's agent (a platinum divinylsiloxane complex) was used as a catalyst. Octa‐N‐alkoxyamines POSS (OT‐POSS) were used as platform to synthesize star polystyrene‐POSS ((PS)8‐POSS) homopolymer and diblock copolymers of poly(styrene‐block‐4‐vinylpyridine)‐POSS ((PS‐b‐P4VP)8‐POSS) and poly(styrene‐block‐acetoxystyrene) ((PS‐b‐PAS)8‐POSS) through NMRP. In addition, subsequent selective hydrolysis of the acetyl protective group of (PS‐b‐PAS)8‐POSS, the poly(styrene‐block‐vinyl phenol) ((PS‐b‐PVPh)8‐POSS) with strong hydrogen bonding group was obtained. The detailed chemical structure and self‐assembled structures of these star block copolymers based on POSS were characterized by 1H NMR, FTIR, SEC, TEM, and SAXS analyses.magnified image

High‐Performance Polybenzoxazine Nanocomposites Containing Multifunctional POSS Cores Presenting Vinyl‐Terminated Benzoxazine Groups

“…The inorganic layered silicate structure of clay, however, does not permit its high dispersion in the organic polymer matrix; therefore, it is essential to pre‐treat the clay with appropriate surfactants 20–22. Recently, novel classes of organic/inorganic hybrid materials based on polyhedral oligomeric silsesquioxanes (POSS) have been developed 23–34. POSS possess an inorganic Si 8 O 12 core, which can be selectively functionalized with seven inert organic hydrocarbon groups and one reactive functional group, or with eight reactive functional groups that may undergo polymerization or cross‐linking 35–44.…”

Pyrene‐functional star polymers as fluorescent probes for nitrophenolic compounds

“…Then, compound 1 was used to produce transient carbon centered radicals in the presence of CuBr/PMDETA catalyst system, which readily reacted with 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) to yield a novel tetra‐TEMPO functional alkoxyamine unimolecular initiator compound ( 2 ). Unimolecular alkoxyamine initiators generate a stable free nitroxide radical (TEMPO) and a carbon‐centered radical on the initiator (small molecule or macroinitiator) at considerably high temperatures . Carbon‐centered radicals initiate the polymerization by attacking double bonds of monomers whereas TEMPO can only mediate the reaction by capping and de‐capping the growing chain ends of the polymer.…”

Synthesis and characterisation of star-shaped liquid crystalline polymer with a POSS core

“…[1][2][3][4][5][6][7] POSS molecules have been successfully incorporated into almost all types of polymers by copolymerisation, [8] grafting [9] or blending. [10] The POSS-functionalised polymers display improved properties in comparison to their pure polymer counterparts such as increased thermal stability, oxidation resistance, enhanced mechanical properties, reduced flammability, a low dielectric constant, [10][11][12][13][14][15][16][17] nanocomposites, [18] self-assembled structures [19][20][21] and photoresists in lithographic technology. [22,23] POSS segment has also been introduced to the liquid crystalline (LC) materials in order to improve the thermal stability and to promote the tendency to form the LC phase.…”