| Summary: | Polyesters with a high glass transition temperature above 130 °C were obtained from limonene oxide (LO) or vinylcyclohexene oxide (VCHO) and phthalic anhydride (PA) in the presence of commercial salen-type complexes with different metals—Cr, Al, and Mn—as catalysts in combination with 4-(dimethylamino) pyridine (DMAP), bis-(triphenylphosphorydine) ammonium chloride (PPNCl), and bis-(triphenylphosphoranylidene)ammonium azide (PPNN<sub>3</sub>) as cocatalysts via alternating ring-opening copolymerization (ROCOP). The effects of the time of precontact between the catalyst and cocatalyst and the polymerization time on the productivity, molar mass (<i>M</i><sub>w</sub>), and glass transition temperature (<i>T</i><sub>g</sub>) were evaluated. The polyesters were characterized by a molar mass (<i>M</i><sub>w</sub>) of up to 14.0 kg/mol, a narrow dispersity <i>T</i><sub>g</sub> of up to 136 °C, and low (<3 mol%) polyether units. For poly(LO-<i>alt</i>-PA) copolymers, biodegradation tests were performed according to ISO 14851 using the respirometric biochemical oxygen demand method. Moreover, the vinyl double bond present in the poly(LO-<i>alt</i>-PA) copolymer chain was functionalized using three different thiols, methyl-3-mercaptopropionate, isooctyl-3-mercaptopropionate, and butyl-3-mercaptopropionate, via a click chemistry reaction. The thermal properties of poly(LO-<i>alt</i>-PA), poly(VCHO-<i>alt</i>-PA) and thiol-modified poly(LO-<i>alt</i>-PA) copolymers were extensively studied by DSC and TGA. Some preliminary compression molding tests were also conducted.
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