Syntheses of semicrystalline aromatic poly(thioether thioether ketone)s (PTTK and PTBTK) and their copolymers with ether analogues

One-pot polymerization between bis(N,N′-dimethyl-S-carbamate)s and activated dihalo compounds was extended to the synthesis of semicrystalline poly(arylene thioether)s as well as their copolymers. Aromatic poly(thioether thioether ketone) (PTTK) and poly(thioether biphenyl thioether ketone) (PTBTK) were synthesized from 4,4′-difluorobenzophenone and bis(N,N′-dimethyl-S-carbamate)s prepared from hydroquinone and 4,4′-biphenol via the Newman-Kwart rearrangement reaction, respectively. Random copolymers were prepared by copolymerization of 4,4′-difluorobenzophenone with a mixture of bis(N,N′-dimethyl-S-carbamate)s or with a bis(N,N′-dimethyl-S-carbamate) and hydroquinone or 4,4′-biphenol. The reactions were carried out in benzophenone solution in the presence of a mixture of Cs₂CO₃ and CaCO₃ as the bases at polymerization temperatures ranging from 200 to 300°C in order to keep the products in solution. All the polymers obtained were semicrystalline, as evidenced from the sharp melting points from the DSC scans for the polymers as prepared. However, the crystallization speeds for these polymers are very different depending on the compositions. The relationships between T_g, T_m, and structures are discussed. PTTK has a T_g of 136°C, T_m of 304°C, and an inherent viscosity of 0.32 dL/g in concentrated sulfuric acid, while PTBTK has a T_g of 173°C, T_m of 351°C, and an inherent viscosity of 0.46 dL/g.