One Pot, One Feeding Step, Two-Stage Polymerization Synthesis and Characterization of (PTT-b-PTMO-b-PTT)_n Multiblock Copolymers

Abstract

We present here the one pot, one step synthesis of poly(trimethylene terephthalate)-block-poly(tetramethylene oxide) multiblock copolymers (PTT-b-PTMO-b-PTT) n by melt polymerization of cyclic oligo(trimethylene terephthalate)s (COTTs) with PTMO macroinitiator. An improved quantitative 1 H NMR characterization technique was developed and applied to investigate the multiblock copolymers' structure with different reaction time by the chain end and functional groups estimation. The polymerization kinetics was revealed, and the results indicated a two-stage polymerization mechanism: melt ring-opening polymerization of cyclic oligo(trimethylene terephthalate)s (COTTs) by PTMO macroinitiator to form triblock copolymers at first stage, followed by the in-situ condensation polymerization of block copolymers to produce multiblock copolymers at second stage. This was further confirmed by the gel permeation chromatography (GPC) and viscosity experiments. To our knowledge, this is the first reported poly(ether ester) multiblock copolymers synthesized by one step polymerization process and with controlled structures. These multiblock copolymers show good thermal stability and double crystalline properties. ■ INTRODUCTIONPoly(ether ester) copolymers are a class of important industrial thermal plastic polymers with polyethers as soft segments and crystalline polyesters as hard segments, and have many applications in molded shoe soles, ski boots, automotive parts, wires and cables, shock absorbers, and biomedical applications. 1−5 The most frequently used soft segments are poly(tetramethylene oxide) (PTMO, also known as poly-(tetrahydrofuran) or PTHF), while the hard segments are aromatic semicrystalline polyesters, due to their good mechanical properties, toughness, chemical resistance, excellent surface appearance, and stable electrical insulation properties. 2,6,7 Normally, these copolymers are synthesized by condensation polymerization of low molecular weights dihydroxyl-terminated polyethers with polyester monomers at high temperatures. 8−12 This process produces random multiblock copolymers with some drawbacks; e.g., the structure of the hard polyester segments is uncontrollable, the total molecular weights of the polymers are not too high, and it requires high vacuum to remove the produced alcohols. 13 Compared to the well-studied poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) polyesters, poly(trimethylene terephthalate) (PTT) has attracted great interest recently due to its excellent elastic recovery and moderate modulus properties, after the economically and ecologically production of 1,3-propanediol monomer from starch by using a fermentation process. 14 However, research works focused on poly(ether ester)s based on PTT are only a few. Szymczyk et al. reported the synthesis of a series of random segmented block copolymers of poly(trimethylene terephthalate) and polyethers by two-step condensation polymerization, with the rigid segments as well as the flexible poly(ethylene oxide) or poly(tetr...

Special odd-even effect of degree of oligomerization on properties of cyclic oligoesters

“…The synthetic route as in references provides a mixture of cyclic oligomers [22,23] . Careful column separation obtained pure cyclic oligoesters.…”

Effect of hard segment length on the properties of poly(ether ester) elastomer prepared by one pot copolymerization of poly(ethylene glycol) and cyclic butylene terephthalate

“…Figure 3 represents the data from viscosity measurements of pCBT 50 -PEG 50 systhesized at 240°C for different time and different catalyst concentration. By fixing the same experimental conditions (the content of PEG and reaction temperature), a higher viscosity measured indicates the higher molecular weight of the measured polymer [7]. In the MarkHouwink equation [η]=KMη α , the K and α parameters are empirical parameters which depend on the solvent-polymer interaction and polymerization temperature.…”

“…The soft segments consist of polyethers, such as poly(tetramethylene oxide)s (PTMOs, also known as poly(tetrahydrofuran)s or PTHFs) and poly(ethylene glycol), have a lower glass transition temperature and provide flexibility to the material. While the hard segments are aromatic semicrystalline polyesters, such as poly(butylene terephthalate) (PBT) [1][2][3][4][5], poly(ethylene terephthalate) (PET) [6], poly(trimethylene terephthalate) (PTT) [7], etc. They bave a highe glass transition temperature and give strength to the materials.…”

“…It is possible that condensation polymerization and transesterification reactions occur at this high temperature [7]. The resultant copolymers were characterized by fourier transform infrared spectrometer (FI-IR), proton nuclear magnetic resonance ( 1 H NMR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).…”

A New Strategy to Synthesize α,ω‐Dihydroxy Multiblock Copolymers via [CpRu(CH3CN)3]PF6/Quinaldic Acid Catalyst

“…Therefore, the α,ω‐dihydroxy MBCs have been rarely prepared via living polymerization . In addition, although Yingfeng Tu and co‐workers reported a new method for the synthesis of MBCs with α,ω‐dihydroxy end groups, the monomers were only cyclic oligo, limiting the composition of block types . Therefore, despite the development of modern science and technology at a fast pace, the synthesis of α,ω‐dihydroxy MBCs is still a challenging task.…”