We report the first example of a regioregular and fully alternating poly (propylene monothiocarbonate) (PPMTC) from the well-controlled copolymerization of two asymmetric monomers, carbonyl sulfide and racemic propylene oxide, using (Salen)CrCl in conjunction with bis(triphenylphosphoranylidene)ammonium chloride. The maximum turnover of frequency of this catalyst system was 332 h(-1) at 25 degrees C. The contents of monothiocarbonate and tail-to-head linkages of PPMTC were up to 100% (based on H-1 NMR spectra) and 99.0% (based on C-13 NMR spectra), respectively. PPMTC samples have number-average molecular weight (M-n) up to 25.3 kg/mol with polydispersity index of 1.41. The very low decomposition temperature of 137 degrees C and high refractive index of 1.63 of PPMTC make it a potential scarifying optical adhesive.