posted on 2023-06-15, 18:46authored byFeifei Kang, Fang Wang, Wenpin Wang, Zhibo Li
The commercially available 1,2-polybutadiene
(1,2-PB)
contains
highly reactive CC bonds and has excellent machinability,
which is an ideal raw material for preparing thermoplastic elastomers.
The preparation of supramolecular cross-linked 1,2-PB thermoplastic
elastomer with good recyclability and excellent mechanical properties
has promising applications. Here, the 1,2-PB elastomers (UPB elastomers)
were prepared by conjugating a few percent 2-ureido-4[1H]-pyrimidinone (UPy) self-complementary quadruple hydrogen bonding
units onto the high molecular weight (Mn) 1,2-PB chains via the thiol-ene click reaction. The used 2-(mercaptoethyl-ureido)-pyrimidinone
derivative (UPy-SH) with a branched alkyl group had good compatibility
with 1,2-PB in organic solvent contributing to a high transparency
of recyclable UPB elastomers. The cross-linking density of UPB elastomers
can be conveniently adjusted by varying the UPy content, which ultimately
determined the mechanical properties of resulting supramolecular elastomers.
Abundant chain entanglements formed by 1,2-PB chains with a high Mn of 455 kDa and strong quadruple hydrogen bonding
networks formed by side UPy units endowed UPB elastomers with excellent
mechanical properties and damping properties. It was found that sample
UPB-2 containing 2 mol % UPy units showed a tensile strength of 13.4
MPa, a high elongation at break of 1167%, a high elastic recovery
of 89% (under large tensile deformation of 400%), a high peak tan
δ value (tan δmax) of 1.4, and an effective
damping temperature range width of 30.6 °C. Moreover, UPB elastomers
have good recyclability given the noncovalent cross-linking networks.
This effective and universal strategy provides some insights into
the design of physically cross-linked high-performance 1,2-polybutadiene
elastomers.