Synthesis and Characterization of Fluorescent Supramolecular Polymers Bearing Pyrene Pendents with Different Spacer Length
Vol. 59, No. 3, pp. 163-170,
Jun. 2022
10.12772/TSE.2022.59.163
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Abstract
We synthesize ureido-pyrimidinone (UPy)-based semicrystalline supramolecular
polymers bearing pyrene pendants (Py-UPCL) and investigate the pyrene spacer length
effect on their supramolecular structure, optical, thermal, and mechanical properties.
Nuclear magnetic resonance (NMR) spectroscopy, capillary viscometry, fluorescence spectroscopy,
and differential scanning calorimetry (DSC) show that the supramolecular chain
extension and crosslinking, i.e., the formation of supramolecular network structure, occurs
in Py-UPCL by the UPy quadruple hydrogen bonding and the pyrene π-π interaction. In
particular, the specific viscosities of Py-1-UPCL with shorter pyrene spacer is higher than
Py-4-UPCL with longer pyrene spacer, and the excimer to monomer intensity ratio (IE/IM) of
Py-1-UPCL (74.9) is higher than that of Py-4-UPCL (14.21), which indicates that shorter
pyrene spacer length stronger formation of the supramolecular network structure. In addition,
Py-4-UPCL (37.7 J g-1) has lower PCL melting enthalpy than Py-1-UPCL (53.5 J g-1)
because of a bulky pyrene topology caused by longer spacer length. As a result, Py-4-UPCL
exhibits two times lower strength and seven times smaller strain compared to Py-1-UPCL.
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