Highly efficient synthesis and characterization of multiarm and miktoarm star-long-branched polymers via click chemistry

Abstract

Two series of 3-12 multiarm star polymers of butadiene and styrene (S-PB and S-PS) with high M n of arms ($20 kg mol À1 ) and narrow PDI (#1.04) were synthesized via click chemistry between azide-terminated polymers and multialkynyl organic molecules. Comparing to the previous report, higher yield of coupling reaction ($85%) was obtained along with increasing arm number and molecular weight of the singlearm polymer (over 4-5 times that before). In particular, 96.1%, as the highest efficiency, occurred in the synthesis of 12-arm star PB. The 4-miktoarm star copolymer of butadiene and styrene was also synthesized with high yield (95.1%), high arm M n and narrow PDI (1.04) by one pot synthesis using click reaction between two different linear polymers (PS-N 3 and PB-N 3 ) and a 4-arm core. All the star polymers were characterized by GPC-MALLS-Viscosity-DRI. These multiarm star polymers exhibit morphologies from random coil to hard sphere depending on the arm-number of the star polymers.Intrinsic viscosity appeared the maximum with increasing arm numbers in star PB and PS, in which PB-4arm and PS-6arm had the highest values, respectively.

Click chemistry strategies for the accelerated synthesis of functional macromolecules

“…Similarly, star polymers with larger number of arms, ranging from 3 to 12 were prepared by CuAAC conjugation of an alkynefunctionalized core with azido-terminated PS and polybutadiene (PB). 712 Star BCPs were also prepared by grafting alkyne-terminated arms including PCL-b-poly-L-lactide (PLLA)-alkyne onto a tetra-azide functionalized core via CuAAC (Figure 44). 713 Nitrile N-oxide based click chemistry was employed for preparing 3,4,or 6 arm star polymers by rapid coupling of PEG arms with highly reactive CN + -O À chain ends in the presence of a multi-allylfunctionalized core under catalyst-free and solvent-free conditions.…”

“…The simplest approach is one-pot conjugation of two different arm polymers, which are in 1:1 ratio, to the core. For example, PCL 2 PLLA 2 713 and PS 2 PB 2 712 4-arm miktoarm star polymers were synthesized via CuAAC coupling of arm polymers to a tetrafunctional core while maintaining a 1:1 molar ratio of two different arms. It should however be noted that one-pot coupling-to approach poses difficulties in determining the composition of miktoarm star polymers accurately.…”

“…A 3‐arm star polymer was synthesized via coupling of P3HT 710 and isotactic polypropylene ( i ‐PP) 711 arms with azide chain ends to a trialkyne‐functionalized core. Similarly, star polymers with larger number of arms, ranging from 3 to 12 were prepared by CuAAC conjugation of an alkyne‐functionalized core with azido‐terminated PS and polybutadiene (PB) 712 . Star BCPs were also prepared by grafting alkyne‐terminated arms including PCL‐ b ‐poly‐ L ‐lactide (PLLA)‐alkyne onto a tetra‐azide functionalized core via CuAAC (Figure 44).…”