Synthesis and Characterization of Multiblock Poly(Ester-Amide-Urethane)s
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Synthesis and Characterization of Multiblock Poly(Ester-Amide-Urethane)s Xingzhou Peng1,2,3,4, Marc Behl1,3, Pengfei Zhang1,2,3, Magdalena Mazurek-Budzyńska1, Yakai Feng2,4, Andreas Lendlein1,3,4* 1
Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, 14513 Teltow, Germany 2 School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China 3 Institute of Chemistry, University of Potsdam, 14476 Potsdam, Germany 4 Tianjin University-Helmholtz-Zentrum Geesthacht Joint Laboratory for Biomaterials and Regenerative Medicine, 14513 Teltow, Germany ABSTRACT In this study, a multiblock copolymer containing oligo(3-methyl-morpholine-2,5-dione) (oMMD) and oligo(3-sec-butyl-morpholine-2,5-dione) (oBMD) building blocks obtained by ring-opening polymerization (ROP) of the corresponding monomers, was synthesized in a polyaddition reaction using an aliphatic diisocyanate. The multiblock copolymer (pBMD-MMD) provided a molecular weight of 40,000 g·mol-1, determined by gel permeation chromatography (GPC). Incorporation of both oligodepsipeptide segments in multiblock copolymers was confirmed by 1H NMR and Matrix Assisted Laser Desorption/Ionization Time Of Flight Mass Spectroscopy (MALDI-TOF MS) analysis. pBMD-MMD showed two separated glass transition temperatures (61 °C and 74 °C) indicating a microphase separation. Furthermore, a broad glass transition was observed by DMTA, which can be attributed to strong physical interaction i.e. by H-bonds formed between amide, ester, and urethane groups of the investigated copolymers. The obtained multiblock copolymer is supposed to own the capability to exhibit strong physical interactions. INTRODUCTION Polydepsipeptides (PDPs) are alternating copolymers composed of α-amino acid and α-hydroxy acid repeating units [1]. The physico-chemical properties of PDPs can be tuned by the amino acid moieties. Oligo- and polydepsipeptides provide the capability to exhibit strong physical interactions by H-bonds formed between the ester and amide linkages of the individual polymer chains [2]. Synthesis of PDPs is typically performed by ring-opening polymerization (ROP) of the relevant morpholine-2,5-diones (MDs) [3, 4]. However, the molecular weight of PDPs obtained from ROP in bulk is limited by the precipitation of the polymer during polymerization. These low molecular weight oligodepsipeptides thus do not provide sufficient elasticity to enable e.g. processing from the melt. An alternative to gain high molecular weights, which can not be obtained by the bulk ring-opening polymerization of the monomers, is the linkage of low molecular weight building blocks in a polyaddition reaction in solution. In addition, different functions from the different building blocks can be integrated into the material. However, multiblock copolymers with oligodepsipeptide segments have been only described as multiblock copolymers in combination with poly(ether ester) blocks [5, 6].
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