Synthesis and Thermal Properties of Poly(α‐Tolylstyrene) by Anionic Polyaddition With Various Ligands

ABSTRACT We investigated the influence of ligands on the anionic polyaddition reactions of α‐tolylstyrene, utilizing hydrogen abstraction by lithium diisopropylamide (LDA) reagents. Using N,N,N′,N′ ‐tetramethylethylenediamine (TMEDA) as a ligand slightly increased the number‐average molecular weight of the obtained poly(α‐tolylstyrene) from 4100 to 4400 with M w / M n of 4.17 after 2 days of polymerization, whereas the use of hexamethylphosphoric triamide (HMPA) as a ligand significantly increased the molecular weight up to 6400 with M w / M n of 11.97. The strong accelerating effect of HMPA ligand is likely due to its strong coordination of HMPA with lithium cations, which increases the hydrogen abstraction efficiency of LDA and enhances the reactivity of the resulting benzyl anions. The resulting polymers, which contain phenyl groups in their main chain, exhibited higher glass transition temperatures ( T g ) and 10% weight‐loss temperature ( T d10 ) compared to polystyrene by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements. In addition, DSC measurement confirmed the miscibility of poly(α‐tolylstyrene) and polystyrene.