Pyridine containing supramolecular shape memory

Chen, S. J., Hu, J. L., Yuen, C. W., Chan, L. K. (2009b), Supramolecular polyurethane networks containing pyridine moieties for shape memory materials. Mater. Lett., 63, 1462. ... 

Supramolecular shape memory polymers containing pyridine 129... 

Abstract This chapter presents the thermaUy-indnced shape memory properties of supramolecular shape memory polyurethane (SMPU) containing pyriine moieties, and compares them with those of other types of SMPU. llie influence of the BINA content and the MDI-BDO content on the thermally-induced shape memory effects (SMEs) of these SMPUs are discussed, including shape fixity, shape recovery and shape recovery stress, as well as the temperature-dependent strain recovery process. A description and analysis of the mechanism of thermaUy-induced SMEs is also provided, covering the effect of temperature and pyridine content on the hydrogen bonds present in SMPUs. 

Abstract This chapter introduces the moisture-induced shape memory effect (SME) observed in supramolecular shape memory polymers, particularly shape memory polyurethane (SMPU), containing pyridine moieties. The moisture absorption of polyurethane networks containing pyridine moeties (PUPy) is discussed followed by an investigation into the effect of relative humidity (RH), temperature, BINA content and MDI-BDO content. The induence of moisture absorption on both the thermal properties and the dynamic mechanical properties of SMPUs is also described, along with the moisture-induced SME mechanism. 

Though recent research has demonstrated the feasibility of fabricating supramolecular SMPs, the studies on the properties of supramolecular SMPs are not systemic. The supramolecular structures significantly affect the mechanical and thermo-mechanical properties of the SMPs. In this book, the influence of hydrogen bonding as the shape memory switch on thermally-active SMPs is introduced. A type of supramolecular SMP, SMPU containing pyridine moieties, is presented. The relation between the thermally-active SME of the SMP and the non-covalent bonding is discussed. 

Most recently, Zhu et al. (2009) and Chen et al. (2009) reported another new type of supramolecular polyurethane network that contains a relatively high fraction of UPy groups for shape memory materials (SMMs). However, to date there has been no systematic account of the SMEs of pyridine-containing polyurethanes (PUPys), and previous studies have not explained the relationship between SMEs and non-covalent bonds. This chapter aims to fill that gap with a detailed study of the thermally-induced SMEs of BIN-SMPUs based on an investigation of their morphology and properties. The influence of the BINA content and pyridine ring fractions on shape fixity, shape recovery, shape stability, thermal-dependent shape recovery and shape recovery force is also systematically examined. 

The main-chain type pyridine containing SMPU has so far not been fully investigated. In future studies, the pyridine ring will be attached to the polymer backbone as a pendant. Based on the hydrogen-bonded supramolecular stmcture, the BIN-SMPUs will have maity unique advantages due to their shape memory, mechanical and damping properties. 

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