스페이서 길이가 다른 파이렌 펜던트를 지닌 형광 초분자형 고분자의 합성과 특성 분석

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.