Styrenic block copolymers and polymer modified bitumen therefrom

A polymer-modified bitumen (PMB) composition comprising:

• 80 to 98 wt. % by weight of a bitumen component;
• and
• 2 to 20 wt. % by weight of a styrenic block copolymer comprising based on the total weight of the styrenic block copolymer:
• (i) 25-60 wt. %, of a diblock copolymer having a peak molecular weight Mp of 50-160 kg/mol, having an A-B structure, and
• (ii) 40-75 wt. % of a coupled radial block copolymer having a peak molecular weight Mp of 200-550 kg/mol, and a structure selected from (A-B)n—X, (A-B-A)n-X, (A-B/IS-A)nX, (A-B)n—X-(B-A)m, (A-B)n—X-(A)m and mixtures thereof,
• wherein,
• each A block is a polymerized vinyl aromatic unit;
• each B block is a polymerized butadiene or an isoprene unit, and B block has a vinyl content of 20-70 wt. % measured by 1H NMR;
• each I is an isoprene unit;
• each S is a styrene unit;
• n and m are independent integers from 1-25 and X is a residual of coupling agent;
• and
• wherein the styrenic block copolymer has:
• a polystyrene content of 25-45 wt. %;
• and
• a High Molecular-weight Polymer (HMP) content of less than 10 wt. %, as described in the description.