Synthesis of star-shaped poly(lactide)s, poly(valerolactone)s and poly(caprolactone)s ROP catalyzed by N-donor tin(II) cations and comparison of their wetting properties with linear analogues

Abstract

In this study, we report the use of N-coordinated tin(ii) cations [L-1 -> Sn(H2O)][OTf](2)<middle dot>THF (1) and [L-1 -> SnCl][SnCl3] (2) (L-1 = 1,2-(C5H4N-2-CH = N)(2)CH2CH2) as efficient ROP catalysts, which, in combination with benzyl alcohol, afford well-defined linear poly(epsilon-caprolactone) (PCL) and poly(delta-valerolactones) (PVL) via an activated monomer mechanism (AMM). Thanks to the versatility of complexes 1 and 2 as catalysts, star-shaped PCL, PVL and PLA were also prepared using three-, four-, five- and six-functional alcohols. The number of arms was determined by SEC-MALS-Visco analysis. Spin-coated thin layers of linear and selected six-armed polymers were further studied in terms of their wettability to water. Attention was focused on the influence of the composition and structure of the polymers. Finally, to increase the hydrophobic properties of the studied polymers, stannaboroxines L-2(Ph)Sn[(OB-(C6H4-4-CF3))(2)O] and L-2(Ph)Sn[(OB-(C6H4-3,5-CF3)(2))(2)O] (L-2 = C6H3-2,6-(Me2NCH2)(2)) were applied.