Solution NMR

Rinaldi, Peter L.; Li, X.; Li, L.; Paudel, Liladhar; Twum, Eric B.

doi:10.1016/b978-0-444-53349-4.00024-8

Cited by 7 publications

(3 citation statements)

References 128 publications

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“…For polymers with molecular weights higher than 10 4 Da, the error becomes greater. This is due to the couplings of 13 C to 1 H take at least 1% integrated peak area from those major peaks of 1 H connected with 12 C. 38,39 Another fact people often overlooked is the different relaxation time of protons at the chain end and on the backbone. If the relaxation delay provided at the front of each acquisition scan was not long enough, NMR signals would be suppressed.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

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

Chen

Huang

et al. 2013

Macromolecules

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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...

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Section: ■ Results and Discussionmentioning

confidence: 98%

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

Chen

Huang

et al. 2013

Macromolecules

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“…5 In research on synthetic macromolecules, the study of their structure, albeit indispensable, has to be augmented by studies of phase separation in multicomponent systems and molecular dynamics in the melt as well as in the solid state of the material. 6 The comprehensive reference by Moller and Matyjaszewski 6 also contains extended reviews on solution NMR 7 and solid-state NMR 8 of polymers. Interestingly, multidimensional solid-state NMR spectroscopy was first developed and applied in the field of synthetic polymer science and provided e.g.…”

Section: ■ Introductionmentioning

confidence: 99%

50th Anniversary Perspective: The Importance of NMR Spectroscopy to Macromolecular Science

Spieß

2017

Macromolecules

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An overview is given of the development of NMR spectroscopy during the past 50 years with emphasis on applications in macromolecular science. The unique versatility of the technique, in particular solid-state NMR, being able to elucidate structure and dynamics over wide ranges in space and time is demonstrated. The examples presented illustrate how advanced NMR methods meet the challenges posed by the delicate interplay of structure and dynamics in macromolecular and supramolecular systems, leading to increasing complexity and functionality. An outlook is given on new developments that overcome the limits of NMR due to its inherently low sensitivity. Likewise, the importance of in situ NMR experiments is pointed out, which can better link the information available from NMR to the properties and function of polymer materials.

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“…Further investigations by applying other characterizations and experimental methods on this topic are still needed in order to verify the above two mechanisms. The three-dimensional nuclear magnetic resonance (3D-NMR , ) method can be another good choice for obtaining additional evidence of radical recombination mechanisms. However, its application in this field has not been reported yet as far as we know, and it is a complicated topic, so will not be included in this paper.…”

Section: Resultsmentioning

confidence: 99%

Electron-Induced Alteration of PLA Chain Structure

Zhang,

Müller,

Boldt

et al. 2023

ACS Appl. Polym. Mater.

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Cross-linked polylactides (PLAs) were produced by electron beam (EB) irradiation at 80 °C using different preset crystallinities (0 to 13.3%), without using crosslinking-promoting additives. Based on functional group conversion detected by Fouriertransform infrared spectroscopy, molecular build-up mechanisms based on a two-stage chain recombination (from geometric T-type to H-type branching) were proposed for EB-induced cross-linking in additive-free PLA. Furthermore, EB-induced PLA crystallization has been discussed based on the combined evidence from morphology, crystallinity, and crystallization behaviors identified by polarized-light optical microscopy, X-ray diffraction, and differential scanning calorimeter (DSC). Several interpretations of the thermal property of EB-induced cross-linked PLA were presented from the point of view of chain scission and cross-linking in a coexisted system. The high irradiation dose obviously shifted the melting temperature (T m ) and cold crystallization temperature (T cc ) of irradiated PLA to a lower region than those of neat PLA. Moreover, the different preset crystallinities of the PLA starting materials did not lead to an obvious difference among irradiated PLAs with respect to T g , T m , T cc , and cross-link density, according to DSC and equilibrium swelling measurements.

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Solution NMR

Cited by 7 publications

References 128 publications

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

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

50th Anniversary Perspective: The Importance of NMR Spectroscopy to Macromolecular Science

Electron-Induced Alteration of PLA Chain Structure

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Solution NMR

Cited by 7 publications

References 128 publications

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

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

50th Anniversary Perspective: The Importance of NMR Spectroscopy to Macromolecular Science

Electron-Induced Alteration of PLA Chain Structure

Contact Info

Product

Resources

About

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

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