Transparent poly(thiourethane-urethane)s based on dithiol chain extender

Abstract

New segmented poly(thiourethane-urethane)s (PTU-Us) (with hard-segment content of 30–60 mass%) were synthesized by a one-step melt polymerization from poly(oxytetramethylene) diol of $$ \overline{M}_{n} $$ = 1,000 g mol−1 or $$ \overline{M}_{n} $$ = 2,000 g mol−1 or poly(hexamethylene carbonate) diol of $$ \overline{M}_{n} $$ = 860 g mol−1 as soft segments, 1,1′-methanediylbis(4-isocyanatocyclohexane) (Desmodur W ®) and (methylenedi-1,4-phenylene)dimethanethiol as a chain extender. The PTU-Us were examined by FTIR, GPC, XRD, DSC, TG, Shore hardness, and tensile testing. Moreover, refractive index, transparency, adhesive properties, and resistance to bacteria and fungi were determined for selected polymers. The obtained high-molar-mass amorphous polymers showed elastomeric or plastic properties. Their T gs were in the range from −70 to 58 °C. The PTU-Us with the polycarbonate soft segments demonstrated a better segmental miscibility (higher T gs), transparency as well as generally higher tensile strength and hardness than those with the polyether soft segments. All the synthesized PTU-Us showed a relatively good thermal stability. The temperature of 1 % mass loss of all PTU-Us was in the range of 236–255 °C. The introduction of thiourethane linkages to polyurethane chain caused increase of the adhesive strength on copper–polymer junction and refractive index values. From the microbial studies, it was found that the obtained polymers had delayed the growth of Gram-positive bacteria.