Linear and three-arm star hydroxytelechelic poly(benzyl β-malolactonate)s: a straightforward one-step synthesis through ring-opening polymerizationElectronic supplementary information (ESI) available: 1H NMR spectra of PMLABe diol synthesized from Bi(OTf)3/PPD and MSA/PPD catalytic systems. See DOI: 10.1039/c5py00724k

Ring-opening polymerization (ROP) of racemic-benzyl β-malolactonate (MLA Be ) initiated by an alcohol such as 1,3-propanediol (PPD) or 2-hydroxymethyl-1,3-propanediol (TMM), and catalyzed by a metal triflate M(OTf) 3 with M = Nd, Bi, proceeded under mild operating conditions (in bulk at 60 °C). The functionality of the alcohol dictates the topology of the resulting hydroxy telechelic PMLA Be . The ROP promoted by the neodymium-based catalytic system afforded a satisfactory activity and control in terms of molar mass and dispersity values ( M n,NMR up to 7000 g mol −1 , M < 1.35). Mechanistic insights revealed that ring-opening of MLA Be took place through the selective oxygen-acyl bond cleavage without undesirable side reactions such as transesterification or crotonisation, as evidenced by NMR and mass spectrometry analyses of the recovered polyesters. The structure of the corresponding α,ω-hydroxy telechelic PMLA Be s was ascertained by 1 H and 13 C{ 1 H} NMR, SEC, and MALDI-ToF mass spectrometry analyses. In comparison, methane and trifluoromethane sulfonic acids did not allow the formation of well-defined PMLA Be diols. Differences in the behavior of MLA Be and the related β-butyrolactone are highlighted. The present Nd(OTf) 3 /PPD or TMM catalytic ROP of MLA Be thus represents a valuable direct synthesis of PMLA Be diols and triols, respectively, without requiring chemical modification of a preformed PMLA Be precursor. Ring-opening polymerization (ROP) of racemic-benzyl β-malolactonate (MLA Be ) initiated by an alcohol (diol or triol) and catalyzed by a metal triflate M(OTf) 3 , afforded α,ω-hydroxy telechelic PMLA Be under mild operating conditions.