Styrene-butadiene block copolymers for tubing applications

A kink-resistant conjugated diene monovinylarene block copolymer comprising from about 35 phm to about 70 phm monovinylarene monomer, the block copolymer formed by the following charge sequence:

• i1-SJ-i2-SK—(S/B)J—(S/B)K-T-CA (A);
• wherein:
• i1 is a first initiator charge;
• SJ is a first charge of the monovinylarene monomer;
• i2 is a second initiator charge;
• SK is a second charge of the monovinylarene monomer;
• (S/B)J is a first dual charge of the conjugated diene monomer and the monovinylarene monomer, wherein the monovinylarene monomer content of (S/B)J is from about 30 wt. % to about 80 wt. %;
• (S/B)K is a second dual charge of the conjugated diene monomer and the monovinylarene monomer, wherein the monovinylarene monomer content of (S/B)K is from about 30 wt. % to about 80 wt. %;
• T is a final charge of the conjugated diene monomer and the monovinylarene monomer or the conjugated diene monomer, wherein the conjugated diene monomer content of T is at least about 70 wt. %;
• and
• CA is a coupling agent charge;
• wherein the first charge and the second charge comprise a total of from about 10 phm to about 45 phm of the monovinylarene monomer;
• and
• wherein a kink resistance of tubing produced from the copolymer and tested in accordance with DIN EN 13868 is less than or equal to about 32 mm.

A conjugated diene monovinylarene block copolymer comprising from about 35 phm to about 70 phm monovinylarene monomer, and comprising polymer chains with the following structures:

• X—X;
• 1)
• X—Y;
• and 2)
• Y—Y;
• wherein 3)
• X is:
• S1—S2—(S/B)1—(S/B)2-T1-;
• and
• Y is:
• S2—(S/B)1—(S/B)2-T1-;
• wherein:
• S1 and S2 are monoblocks of the monovinylarene monomer, wherein a total weight of S1 and S2 is from about 35 to about 45 wt. % of X, and S2 is from about 14 to about 26 wt. % of Y;
• (S/B)1 is a mixed block of the conjugated diene monomer and the monovinylarene monomer, wherein the monovinylarene monomer content of (S/B)1 is from about 30 wt. % to about 80 wt. %;
• (S/B)2 is a mixed block of the conjugated diene monomer and the monovinylarene monomer, wherein the monovinylarene monomer content of (S/B)2 is from about 30 wt. % to about 80 wt. %;
• and
• T1 is a mixed block of the conjugated diene monomer and the monovinylarene monomer or a monoblock of the conjugated diene monomer, wherein the conjugated diene monomer content of T1 is at least about 70 wt. %, wherein T1 is from about 12 to about 32 wt. % of X, and T1 is from about 16 to about 32 wt. % of Y;
• and
• wherein a kink resistance of tubing produced from the copolymer and tested in accordance with DIN EN 13868 is less than or equal to about 32 mm.