Base-Assisted Polymerizations of Elemental Sulfur and Alkynones for Temperature-Controlled Synthesis of Polythiophenes or Poly(1,4-dithiin)s

Facile Synthesis of Functional Polytrithiocarbonates from Multicomponent Tandem Polymerizations of CS2, Thiols, and Alkyl Halides

Polytrithiocarbonates have attracted significant attention recently because of their good thermal stability, light refractivity, crystallinity, and mechanical properties; however, the exploration of their structures and functionalities has been limited by their synthetic approaches. Multicomponent polymerization featuring simple monomers, mild conditions, diversified product structures, and high efficiency could provide a powerful and versatile tool to synthesize various polytrithiocarbonates from commercially available monomers. Herein, a robust and efficient multicomponent tandem polymerization (MCTP) of CS2, dithiols, and alkyl halides was developed in DMF with K2CO3 at room temperature in air to synthesize 12 polytrithiocarbonates with diversified and systematically tuned structures, high molecular weights (Mns up to 37900 g/mol), and high yields (up to 93%). Depending on the different polymer backbone structures, amorphous polytrithiocarbonates showed excellent breaking elongations, and crystallinic polytrithiocarbonates possessed a large process temperature window (about 200 °C) and good mechanical performance (σB of 23.6 MPa and εB of 858%), whose tensile strength could be dramatically enhanced to 87.5 MPa after uniaxial extension deformation. The upper critical solution temperature (UCST) in organic solvents, together with nonconventional luminescence, were observed for the crystallinic polytrithiocarbonates, even without any aromatic ring. This efficient, robust, mild, and economic MCTP of CS2 thus opened up an avenue for the facile construction of polytrithiocarbonates with structural diversity, bringing modulable mechanical, thermal, luminescent, and thermal-responsive properties, which would greatly broaden the scope of structures and applications of sulfur-containing polymers.

Easy Synthetic Access to High-Melting Sulfurated Copolymers and their Self-Assembling Diblock Copolymers from Phenylisothiocyanate and Oxetane

Although sulfurated polymers promise unique properties, their controlled synthesis, particularly when it comes to complex and functional architectures, remains challenging. Here, we show that the copolymerization of oxetane and phenyl isothiocyanate selectively yields polythioimidocarbonates as a new class of sulfur containing polymers, with narrow molecular weight distributions (Mn=5-80 kg/mol with Đ≤1.2; Mn,max=124 kg/mol) and high melting points of up to 181 °C. The method tolerates different substituent patterns on both the oxetane and the isothiocyanate. Self-nucleation experiments reveal that π-stacking of phenyl substituents, the presence of unsubstituted polymer backbones, and the kinetically controlled linkage selectivity are key factors in maximising melting points. The increased tolerance to macro-chain transfer agents and the controlled propagation allows the synthesis of double crystalline and amphiphilic diblock copolymers, which can be assembled into micellar- and worm-like structures with amorphous cores in water. In contrast, crystallization driven self-assembly in ethanol gives cylindrical micelles or platelets.