Hydrogenated poly(styrene-co-α-methylstyrene) polymers: A new class of high glass-transition-temperature polyolefins

We demonstrate a method to prepare high glass-transition-temperature (T_g) materials with a two-step process - anionic copolymerization of α-methylstyrene with styrene (leading to copolymers referred to as SAMS), with subsequent catalytic hydrogenation. The product, poly(cyclohexyl ethylene-co-2-cyclohexyl propylene), is referred to as PCEP_x, where the subscript denotes the molar percentage of 2-cyclohexyl propylene units in the copolymer. PCEP_x exhibits T_g values between 140 and 178 °C depending on the composition and composition distribution in the polymerization product. To increase the toughness of PCEP_x, we copolymerized SAMS with butadiene followed by hydrogenation to form PCEP_x/PEE_y block copolymers, where PEE_y refers to poly(ethylene-co-ethyl ethylene), and γ denotes the molar percentage of ethyl ethylene segments. T_g values as high as 162 °C were achieved for these block copolymers.