Synthesis of polymers from carbon disulfide

Carbon disulfide is produced from carbon and sulfur, whose applications to fabricate organic materials are very limited.
We are investigating polymer syntheses based on five-membered cyclic dithiocarbonates, which can be obtained from carbon disulfide and epoxides. The potential applications of the polymers are high refractive index materials and metal absorption materials.

Synthesis of star-polymers from tri(mercapto-thiourethane) derived from three-membered five-membered cyclic dithiocarbonate

Thiols are easily oxidized to form disulfides, and hence commercially available multifunctional thiols are very limited. Contrary to this, epoxides, which are the precursors for cyclic dithiocarbonates and mercaptothiourethanes, have diversity in their structure. Accordingly, we employed multifunctional five-membered cyclic dithiocarbonates as precursors for multifunctional thiols.

When a trifunctional five-membered cyclic dithiocarbonate was reacted with amines, trithiols bearing functional groups originating from amines were produced. The trithiols are typically stable under air atmosphere. The anionic polymerization of propylene sulfide initiated from the trithiols afforded three-armed polymers bearing functional groups. The trithiols could be converted to tris(trithiocarbonate)s by the reaction with carbon disulfide and benzyl chloride. The tris(trithiocarbonate)s served as RAFT agents for polymerization of styrene.


Facile synthesis of core-crosslinked graft copolymers using poly(mercapto-thiourethane) as a polymeric chain transfer agent

Polymers bearing thiol groups have been used as polymeric chain transfer agents for synthesis of graft copolymers via graft-from type radical polymerization. However, thiols are both radically and nucleophilically reactive, hence synthesis of polymers bearing thiol moieties required protection-deprotection processes. By contrast, polyaddition of bifunctional cyclic dithiocarbonates and diamines give polythiourethanes having thiol groups in the side chain (poly(mercaptothiourethane)) without protection-deprotection processes. The polyaddition under an air atmosphere gave a cross-linked poly(mercaptothiourethane). In the presence of this cross-linked polymer, radical polymerizations of styrene and MMA yielded core-crosslinked copolymers. When linear poly(mercaptothiourethane)s were employed, graft copolymers with controllable molecular weights were obtained.五員環ジチオカーボナートを利用するグラフトコポリマーの合成

Three-component polyaddition via transformation of reaction modes from nucleophilic to radical

Typical three-component reactions consume two reactive species at first. The products stabler than the initial reactants must react with the remained most unreactive species. Accordingly, excess amounts of components or elimination of stable byproducts, which are responsive to low atom economy, were neccessary. We overcame this problem by transformation of reaction modes. Theused reaction is nucleophilic addition of amines to cyclic dithiocarbonates affording thiols that can react radically. When dithiocarbonates, diamines, and a diyne was used as monomers, the radically reactive diyne never react with others unless thiols are produced by the nucleophilic addition of the amines to the dithiocarbonates. Namely, the polymerization proceeds via the following two steps; the first nucleophilic addition of diamines to cyclic dithiocarbonates, and the subsequent radical addition of the produced dithiols to the diyne. The atom economy is very high (~97%). The resulting polymers can collect Au and Pd salts from their aqueous solutions.

Detail of the works before 2005 is described in the following review.

Carbon Dioxide and Carbon Disulfide as Resources for Functional Polymers.
Ochiai, B.; Endo, T. Prog. Polym. Sci. 30 (2), 183-215 (2005) Link to Science Direct

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