Poly(ethylene oxide-b-3,3-dimethylthietane) was prepared by coupling of preformed poly-3,3-dimethylthietane (PDMT) with poly(ethylene oxide) (PEO). PDMT was endcapped with 2,4-toluene diisocyanate (TDI) and then reacted with molar excess of PEO. AB type block polymers were obtained. Absorption by complexation of silver nitrate and iodine by these block polymers was investigated. It was found that the presence of the PEO segmer in the block polymer was essential for complexation. Iodine absorption was not accompanied by other side reactions leading to chain scission of the polysulfide, as was found with poly(propylene sulfide).