Investigating whether phthalic thioanhydride (PTA) can compatibilize epoxides with elemental sulfur (Figure ), we attempted ROTERP employing 1 eq. Lithiumbenzyloxide (LiOBn, generated in situ from Li[N(SiMe3)2] and BnOH), 500 eq. propylene oxide (PO), 50 eq. PTA and 100 eq. S (i.e. 1/8 eq. S8) at room temperature for 24h resulting in full PTA conversion (Table run #1). H NMR analysis of the product mixture reveals the formation of broad indicative polymer resonances in 97% selectivity alongside some sharp resonances for small molecule byproducts. The polymer could be easily isolated by precipitation in methanol and centrifugation. Gel permeation chromatography (GPC) shows an apparent weight averaged molecular weight of 22 kg/mol with a polydispersity of 1.5 which confirms the macromolecular nature of the product. NMR analysis reveals the aromatic region of the spectrum to feature two dominant CH resonances at 7. 4 ), and this is indicative of a symmetrically substituted aryl diester unit. Accordingly, the tertiary CH proton from PO ring-opening, likewise correlate to the quaternary carbon resonance at 166 ppm, implying that these so-called head-positions sit adjacent to the phthalate core. The CH2 tail position of the ring-opened PO appear between 3.5 and 2.6 ppm which in comparison to literature known polymers can be tentatively assigned to be connected to oligosulfide -Sxlinks. The formation of these is confirmed by Raman spectroscopy showing indicative absorbances between 560 and 420 cm -1 . Close comparison of these region to small molecule di-RSSR, tri-RSSSR and tetra-RSSSSR standards indicates that while some disulfide links appear to have formed, a substantial proportion of the -Sx-links comprise tri and tetrasulfides (ESI Figure ). Taken together, the spectroscopic data suggest the selective formation of a Poly(ester-alt-Sx) sequence in which the -Sx-are flanked by CH2 tail-groups while the phthalate esters sit next to CH head groups of the ring opened epoxides. To investigate if the oligosulfide linkage distribution is affected by the amount of elemental sulfur supplied in the starting monomer feed we halved the amount of supplied sulfur (run #2). Here the reaction rate slowed down substantially necessitating longer reaction times to reach high monomer conversion with polymer formation in 93% selectivity. Raman spectroscopy now reveals a more prominent formation of disulfide links suggesting tunability of the -Sx-linkage distribution with the supplied initial sulfur feed.