Studies On Synthesis And Properties Of Network Supramolecular Polyurethanes Based On Quadruple Hydrogen-bonding

The supramolecular polymers are linked by non-covalent bonds to form physical crosslinking. Many novel materials can be synthesis by using this kind of property. There are a variety of non-covalent bonds to form the supramolecular polymers, but the hydrogen bond is the most useful because of its selectivity and reversibility. In recent years, the ureidopyrimidinone (UPy) groups discovered by Sijbesma has been widely used in the supramolecular polymers. The UPy group can achieve a high dimerization in the suitable solvent with a good thermal stability.The polymer’s mechanical properties can be improved significantly by using UPy groups to form a linear supramolecular polymer. In this thesis we introduce UPy groups into the polyurethane to form a supramolecular polyurethane with physical cross-linked network. Compared to the traditional polymer with chemical network, the supramolecular polyurethane are much more elastic and processable.Ureidopyrimid one (UPy)-contained polyurethanes were synthesized from4,4’-diphenylmethane diisocyanate and polytetramethylene glycol(PTMG), incorporating2-methyl-2-UPy(2-ureido-4[1H]-pyrimidone)-1,3-propanediol as chain extender, of which the structure was confirmed by FTIR and1H-NMR spectrum. The results of tensil test demonstrated that the mechanical properties of polyurethanes were greatly improved by introducing UPy group in the side chain. In Dynamic Mechanical Thermal Analysis, with the increase of the content of UPy, the glass transition temperature increased correspondingly, whereas the peak value of tan δ decreased. In the wide frequency field, with the increase of the content of UPy, the influence of frequency to peak value of tan δ and storage modulus (E’) would led to the movement of peak value of tan δ towards low frequency, the diminishment and flattening of the peak area at tan δ and the increase of E.A linear supramolecular polyurethane (HP1400-UPy) can be obtained through interaction-NCO end groups in prepolymer of polyurethane with-NH2groups in ureidopyrimidone (UPy), and a novel lowpolymer with three UPy units (T5000-UPy) was synthesized by Jeffamine T5000with-NCO groups in UPy. Then a series of network supramolecular polyurethane were obtained by different ratio HP1400-UPy and T5000-UPy, of which structure was confirmed by FTIR and1H-NMR spectrum. TGA thermal analysis indicated that the introduction of T5000-UPy had only a flew influence on the thermo stability of network supramolecular PU, but the tensile test showed greatly improved mechanical properties compared to the linear supramolecular PU. In Dynamic Mechanical Thermal Analysis, with the increase of the content of T5000-UPy product much more networks in supramolecular PU would lead tanδreduced correspondingly, whereas Tg and storage modulus (E’) increase.