The present disclosure discloses a method for preparing high-activity polyphenylene sulfide (PPS) by regulating and controlling a water content in a polymerization process and a high-efficiency polyphenylene sulfide resin prepared thereby. The preparation method includes: carrying out a polycondensation reaction with sodium hydrosulfide and p-dichlorobenzene as raw materials and N-methyl-2-pyrrolidone as a solvent until a conversion rate of the p-dichlorobenzene reaches 97% or above, adding deionized water, reducing the temperature in a reactor to 250-260 C. for heat preservation for 1-3 h, and performing cooling for post-treatment; and calculated with the sodium hydrosulfide as 1.0 mol, a molar amount of the added deionized water is 1.0-2.5 mol. The method for preparing high-activity polyphenylene sulfide disclosed in the present disclosure can be simultaneously realized in a PPS polymerization process, and that is to say, an end-capping reagent is not required to be additionally added to affect the molecular weight and thermal stability of the finally prepared PPS; and activation treatment is also not required to be performed after the PPS resin is prepared to additionally increase the technological process and the production cost.

The present invention aims to provide a polymer material that has a high refractive index and can be suitably used for applications such as optical applications. The present invention relates to the sulfur-containing polymer containing at least one structural unit selected from the group consisting of a structural unit (A) represented by the following formula (1), a structural unit (B) represented by the following formula (2), and a structural unit (C) represented by the following formula (3); and a reactive functional group, ##STR00001##
wherein X.sup.1, X.sup.2, and X.sup.3 are the same as or different from each other and are each an optionally substituted divalent aromatic hydrocarbon group.

The present invention aims to provide a polymer material that has a high refractive index and can be suitably used for applications such as optical applications. The present invention relates to the sulfur-containing polymer containing at least one structural unit selected from the group consisting of a structural unit (A) represented by the following formula (1), a structural unit (B) represented by the following formula (2), and a structural unit (C) represented by the following formula (3); and a reactive functional group, ##STR00001##
wherein X.sup.1, X.sup.2, and X.sup.3 are the same as or different from each other and are each an optionally substituted divalent aromatic hydrocarbon group.