SUMMARY: Successful room temperature ring-opening polymerization (ROP) of e-caprolactone and d-valerolactone has been carried out using SmX 2 (X = I, Br, and cyclopentadienyl (Cp)) catalysts. SmI 2 in the presence of metallic Sm was found to have enhanced reactivity as room temperature ROP initiator for lactones as compared to pure SmI 2 . SmBr 2 and SmCp 2 showed increased reactivity compared with the Sm/SmI 2 system due to their higher reductive power. The catalyst concentration and time of polymerization showed a marked effect on number-average molecular weight (M -n ). There was a decrease in M -n on increasing reaction time and decreasing catalyst concentration. The initiation mechanism is discussed based on end group analysis of low molecular weight polymers.

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Reductive coupling of aromatic carbonyl compounds in the presence of stoichiometric amounts of Sm(II) compounds such as SmI2, SmI2/TMSiCl, SmBr2, Sm/TMSiBr, SmCp2 resulted in hydrobenzoin derivatives. OH‐functionalized poly(p‐xylylene)s (OH‐PPX) were obtained by reductive coupling of aromatic dialdehydes. The usage of solubilizing groups as well as the use of trimethylsilylchloride (TMSiCl) and trimethylsilylbromide (TMSiBr) enhanced the polymerizability of monomers under study. In spite of moderate yields high molecular weight polymers were obtained.

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The focus of this study is on reductive couplings of aromatic monoaldehydes and dialdehydes utilizing catalytic amounts of Sm(II) compounds and different co‐reductants such as Mg turnings and Mg/Hg alloy in the presence of trimethylsilylchloride (TMSiCl). High educt and no side products have been observed using 10 mol% of SmI2 and excess of Mg turnings activated by C2H4Br2 in the presence of TMSiCl. Low yields of hydrobenzoin were observed when SmCp2 replaced SmI2. The reductive coupling polymerization of aromatic dialdehydes can be conducted under catalytic conditions with 12 mol% of SmI2 and excess of Mg or Mg/Hg in the presence of TMSiCl in THF. OH‐functionalized PPXs were obtained with moderate yields polymer and Mn of up to 16 000 g/mol.