Synthesis and shape memory behavior study of hyperbranched poly(urethane-tetrazole)

Abstract

A novel hyperbranched poly(urethane-tetrazole) (HPUTZ) was synthesized via the "A2+BB 2 ' " approach using hexadiisocya- nate (HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole (HAPTZ). The molecular structure was characterized by FTIR and 1 H NMR spectroscopy. The number average molecular weight was measured to be 1.05×10 4 g/mol with a polydispersity of 1.27 by GPC analysis. The HPUTZ was further cured by the semi-adduct (PEG-IPDI) from polyethylene glycol (PEG) reacting with isophorone diisocyanate (IPDI) to form the crosslinked HAPTZ-PU film in different ratio of HAPTZ to PEG-IPDI. The glass transition temperature of HAPTZ-PU increased from 44.9 to 56.4 °C as the HPUTZ content increased from 20% to 33% from the DSC analysis. The DMA results indicated that the HPUTZ-PU with 20% HPUTZ possessed the highest storage mod- ulus and loss tangent. However, the storage modulus increased with the increasing of HPUTZ segment at higher temperature. The shape memory study showed that all the films presented the excellent shape memory function. Over 98% shape recovery could be obtained for the HAPTZ-PU with 20%-33% HAPTZ segment content within 60 s in the tension deformation test and within 40 s at 80 °C in the bend deformation test. synthesis, hyperbranched poly(urethane-tetrazole), shape memory behavior, thermal property