ATRP of POSS Monomers Revisited: Toward High-Molecular Weight Methacrylate–POSS (Co)Polymers

Abstract

For the first time, ATRP was successfully employed for homopolymerization of a commercial methacrylate-functionalized polyhedral oligomeric silsesquioxane (POSS) monomer, iBuPOSSMA, to high molecular weights. It was found that iBuPOSSMA has a low ceiling temperature (T c); therefore, low temperatures and/or high initial monomer concentrations need to be used in order to avoid low degrees of polymerization that had been observed previously. The values of T c, as well as of the polymerization enthalpy ΔH p and entropy ΔS p were determined to be 130 °C (at [M]0 = 1 M), −41 kJ mol–1, and −101 J mol–1 K–1, respectively. Under optimized conditions, poly(iBuPOSSMA) homopolymers having low dispersity and high M n, ranging from 23 000 to 460 000, were obtained in a well-controlled ATRP process. Moreover, various block copolymers having high-M n poly(iBuPOSSMA) blocks were prepared by copolymerization of iBuPOSSMA with methyl methacrylate and styrene.

Copper Wire–Catalyzed RDRP in Nonpolar Media as a Route to Ultrahigh Molecular Weight Organic–Inorganic Hybrid Polymers

“…The highest conversion (95%) was reached with Me 6 TREN (entry 4). This value corresponds well to the limiting conversion of ≈97% that can be estimated from the thermodynamic parameters we determined in our previous study . The M n values obtained by size‐exclusion chromatography (SEC) with polystyrene standards are known to be considerably underestimated; however, realistic values [ M n (est.)]…”

“…Various factors might be responsible for the decreased polymerization rates observed when high‐MW poly( i BuPOSSMA) are aimed. As has been shown previously, depropagation becomes increasingly prominent as the monomer conversion increases, diminishing gradually the efficient rate constant of propagation ( k p eff ) . In addition, the polymerization mixtures tend to be rather diluted (in molar terms) due to the high MW and limited solubility of the solid i BuPOSSMA monomer.…”

“…In ATRP, this was due to low conversions that were initially ascribed to the assumed inaccessibility of growing chain ends to the catalytic complex . However, in our recent study on ATRP of the most widely utilized commercial POSS‐methacrylate, isobutyl POSS methacrylate ( i BuPOSSMA), we showed that the decreased thermodynamic polymerizability (a low ceiling temperature) of the monomer was the key factor responsible for the limited conversions observed in the early works . At low temperatures and with high initial monomer concentrations, we achieved high monomer conversions and relatively high‐MW poly( i BuPOSSMA) homopolymers.…”

POSS-based glycidyl methacrylate copolymer for transparent and permeable coatings

“…In the cubic POSS, Si atoms occupy the corners of a cube and oxygen atoms located at the edges of core (2,3), but peripheral organic groups in the shell give them several advantages over conventional inorganic particles with a wide variety of potential substituent groups attached (4). The choice of substituent groups not only provides POSS selective solubility in organic or aqueous solvents, but also the ability dispersed in many polymers and the specific chemical reactivity of different substituent groups that can be directly incorporated the POSS into polymer backbones or side groups or networks by covalent bonding (5)(6)(7)(8)(9)(10)(11). Therefore, the outer shell of POSS effectively controls the interaction between the POSS units and the surrounding matrix (12).…”

“…Therefore, the outer shell of POSS effectively controls the interaction between the POSS units and the surrounding matrix (12). What is more, the shell substituents could offer immense opportunities for synthesis of organic-inorganic hybrid copolymers (5)(6)(7)(8)(9)(10)(11). It has been reported that the introduction of POSS into polymers can distinctly enhance the native polymer properties in glass transition temperature (13)(14), decomposition temperature (15), surface hardness, mechanical properties, flammability resistance and oxidation resistance attributed to the inorganic octahedral cage structure of POSS (16)(17)(18).…”