Preparation method of crystalline polymonothiocarbonate

The invention belongs to the field of polymer materials, and relates to a preparation method of a crystalline polymonothiocarbonate. An an asymmetric copolymerization reaction takes place between mesomeric epoxyalkane and carbonyl sulfide under the action of a chiral catalyst to form the crystalline polymonothiocarbonate with a highly isotactic structure. The content of monothiocarbonate units ina polymer chain of the crystalline polymonothiocarbonate is 99% or more than 99%; the Isotactic degree of the polymer is 75% to 99%; and a semi-crystalline material can be obtained after the polymer is simply heat-treated. The crystalline polymonothiocarbonate is prepared by polymerizing the carbonyl sulfide and the mesomeric epoxyalkane, and the mesomeric epoxyalkane is wide in sources, so that aplurality of crystalline polymonothiocarbonates can be prepared; the preparation method is mild in reaction conditions, high in catalyst activity, and high in polymer selectivity; and the prepared polymonothiocarbonate is con