scholarly journals Insight into the Alcohol-Free Ring-Opening Polymerization of TMC Catalyzed by TBD

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1589
Author(s):  
Fabrice Azemar ◽  
Olinda Gimello ◽  
Julien Pinaud ◽  
Jean-Jacques Robin ◽  
Sophie Monge
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Polymer Chains ◽  
Size Exclusion ◽  
Trimethylene Carbonate ◽  
Free Ring ◽  
Molecular Weights ◽  
Cyclic Polymer ◽  
Exclusion Chromatography

We report herein a study on the alcohol-free, ring-opening polymerization of trimethylene carbonate (TMC) in THF, catalyzed by 1,5,7-triazabicyclo [4.4.0] ec-5-ene (TBD) with ratios nTBD/nTMC ranging between 1/20 and 1/400. In all cases, the reaction proceeds very rapidly, even faster than in the presence of alcohol initiators, and provides PTMC with molecular weights up to Mn = 34,000 g mol−1. Characterization of the obtained PTMC samples by MALDI-TOF mass spectrometry, triple detection size exclusion chromatography and 1H NMR spectroscopy reveals the presence of both linear and cyclic polymer chains.

Synthesis and characterization of new, liquid, branched poly(methylvinylborosiloxanes)

e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Jerzy Chruściel ◽  
Marzena Fejdyś ◽  
Witold Fortuniak
Keyword(s):  
Functional Groups ◽  
Atomic Spectroscopy ◽  
Size Exclusion ◽  
Random Structure ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Siloxane Oligomers ◽  
Exclusion Chromatography ◽  
Ether Solution

Abstract New liquid branched poly(methylvinylborosiloxanes) (br-PMVBS) of random structure were synthesized in three steps. By reacting boric acid with an excess of dimethyldichlorosilane (Me2SiCl2) in dry ether a “borosiloxane precursor”: tris(chlorodimethylsilyl) borate B(OSiMe2Cl)3 was prepared. In the second step of synthesis ether solution of B(OSiMe2Cl)3 was added to a mixture of appropriate organic chlorosilanes (Me2SiCl2, MeViSiCl2, MeSiCl3, and Me3SiCl) and all reagents were reacted with stoichiometric amounts of water, in the presence of pyridine (as an acceptor of HCl), in dry ether, at low temperature (usually at -10 to 0 C). In order to fully react (“to block”) trace silanol groups, reactions of intermediate PMVBS with additional batches of Me3SiCl were carried out in the third step, C5H5N·HCl was filtered off and washed with a dry ether. The solvent was distilled off from filtrates and low molecular weight siloxane oligomers were removed by a vacuum distillation at 130-150 C. Chemical structures of br-PMVBS were confirmed by elemental analysis and spectroscopic methods (FTIR, emission atomic spectroscopy ICP-AES, and NMR: 1H, 29Si and 11B). On the basis of analysis of their 29Si-NMR spectra the microstructure of polysiloxane chains was proposed. The prepared br-PMVBS had in their structures: triple branching borosiloxane units: BO1.5 and in some cases methylsiloxane moiety CH3SiO1.5 (T). They contained linkages: Si-O-Si, Si-O-B, vinyl(methyl)siloxane functional groups (CH2=CH)MeSiO (Dvi), dimethylsiloxane mers (CH3)2SiO (D), and non-reactive trimethylsiloxy terminal groups (CH3)3SiO0.5 (M), but they did not have: hydroxyl functional groups: Si-OH and B-OH, and sensitive to water B-O-B linkages. Molecular weights of br-PMVBS (Mn = 1500-3300 g/mol; Mw = 3800-7400 g/mol) and their polydispersity (Mw/Mn = 2.0-2.5) were determined by a size exclusion chromatography (SEC).

Σύνθεση γραμμικών και αστεροειδών πολυμερών αποτελούμενα από συστάδες με υψηλή παράμετρο αλληλεπίδρασης Flory-Huggins χ

2020 ◽  
Author(s):  
Μαρία-Μαλβίνα Σταθουράκη
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
X Ray ◽  
X Ray Scattering ◽  
Exclusion Chromatography

Σκοπό της διατριβής αυτής αποτελεί η σύνθεση και η μελέτη της αυτοοργάνωσης γραμμικών και αστεροειδών συμπολυμερών με υψηλή παράμετρο αλληλεπιδρασης Flory-Huggins, χ. Τα πολυμερή αυτά, λόγω της μικρής αναμιξιμότητας που παρουσιάζουν τα συστατικά τους, έχουν την δυνατότητα σε μικρά μοριακά βάρη να μπορούν να σχηματίζουν πολύ μικρές και καλά καθορισμένες δομές κατά το μικροφασικό διαχωρισμό. Αρχικά, πραγματοποιήθηκε η σύνθεση των γραμμικών δισυσταδικών συμπολυμερών πολυ(2-βινυλοπυριδίνης)-b-πολυ(l-λακτιδίου) (P2VP-b-PLLA) και των τρισυσταδικών πολυ(l-λακτιδίου)-b-πολύ(διμεθυλοσιλοξάνη)-b-πολύ(l-λακτιδίου) (PLLA-b-PDMS-b-PLLA), καθώς και γραμμικών και αστεροειδών συμπολυμερών πολύ(στυρένιο)-b-πολυ(μονομεθακρυλική γλυκερόλη), PS-b-PGMA, (πολυστυρένιο)2(πολυ(μονομεθακρυλική γλυκερόλη)), (PS)2(PGMA), και (πολυστυρένιο)3(πολυ(μονομεθακρυλική γλυκερόλη)), (PS)3(PGMA), σε διάφορες αναλογίες μοριακών βαρών των συστατικών τους. Χρησιμοποιήθηκαν τεχνικές ζωντανού ανιοντικού πολυμερισμού για τη σύνθεση της P2VP, καθώς και για τη σύνθεση των αστεροειδών πολυμερών, ενώ η σύνθεση των PLLA πραγματοποιήθηκε με χρήση πολυμερισμού διάνοιξης δακτυλίου (Ring Opening Polymerization, ROP). Ο μοριακός χαρακτηρισμός των πολυμερών έγινε μέσω Χρωματογραφίας Αποκλεισμού Μεγεθών (Size Exclusion Chromatography, SEC) και Φασματοσκοπίας Πυρηνικού Μαγνητικού Συντονισμού Πρωτονίου (Nuclear Magnetic Resonance Spectroscopy, 1H-NMR). Τέλος, τίθενται τα αποτελέσματα που αφορούν τα γεωμετρικά χαρακτηριστικά (μέγεθος, μορφολογία) των περιοδικών νανοδομών που σχηματίζουν στο τήγμα τα συμπολυμερή, μέσω σκέδασης ακτίνων Χ σε μικρές γωνίες (Small-angle X-ray Scattering, SAXS).

Characterization of polyamides 6, 11, and 12. Determination of molecular weight by size exclusion chromatography (IUPAC Technical Report)

2004 ◽  
Vol 76 (11) ◽  
pp. 2009-2025 ◽  
Author(s):  
E. C. Robert ◽  
Rudolf Bruessau ◽  
J.-E. Dubois ◽  
Bernard Jacques ◽  
Nico Meijerink ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Working Party ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Relative Standard ◽  
Exclusion Chromatography ◽  
Iupac Commission ◽  
Commercial Polymers

This report presents the results from IUPAC Working Party IV.2.2 of the global trial within the framework of IUPAC Commission IV.2, “Characterization of Commercial Polymers”. The results were compared on the basis of molecular weight obtained by size exclusion chromatography (SEC)using different techniques practiced in participating laboratories, the majority of which were materials suppliers. The practical methodologies used different solvents for the polymers, in particular, benzyl alcohol, 1,1,1,3,3,3 hexafluoropropan-2-ol and tetrahydrofuran; the latter solvent was used after chemical modification of the polyamides, in general with trifluoroacetic anhydride. Eight laboratories participated in the trial. The repeatability for molecular weight in each laboratory was good, whatever technique was used, the relative standard deviation averaged over all laboratories being around 3%. The deviations in distribution of molecular weights with different experimental methodologies were broader, but were reasonably good despite the diversity of methods. The differences in the distribution correspond to a confidence interval of about 30% in molecular weight.

Characterization of lignin residues derived from the alkaline hydrolysis of glycol lignin

1990 ◽  
Vol 68 (1) ◽  
pp. 82-89 ◽  
Author(s):  
Ronald W. Thring ◽  
Esteban Chornet ◽  
Jean Bouchard ◽  
Pierre F. Vidal ◽  
Ralph P. Overend
Keyword(s):  
Alkaline Hydrolysis ◽  
Size Exclusion ◽  
Absorption Intensity ◽  
Molecular Weights ◽  
Carbon Carbon Bonds ◽  
Lower Oxygen ◽  
Exclusion Chromatography ◽  
Hydrolysis Of ◽  
C Nmr

Lignin residues from the alkaline hydrolysis of solvolytic lignin have been characterized by elemental analysis, size exclusion chromatography, Fourier transform infrared spectroscopy, 13C NMR, and for methoxyl content. All lignin residues were found to have higher carbon and lower oxygen contents than the original glycol lignin. Methoxyl contents decreased with increasing severity of treatment. All treated lignins have lower molecular weights than the original, which is indicative of the extensive depolymerization of glycol lignin by alkaline hydrolysis. The appearance of new bands in the 3050–2800 cm−1 and 900–800 cm−1 regions in the infrared spectra along with increasing absorption intensity under more severe conditions demonstrates that, despite the tendency to depolymerization, new carbon–carbon bonds are formed due to repolymerization reactions. 13C NMR revealed that extensive cleavage of the side chains and β-O-4 interunit linkages had occurred during alkaline hydrolysis and that the new bonds formed due to condensation reactions at higher severities are of the methine, methylene, methyl and carboxyl types. Keywords: residual lignins, alkaline hydrolysis, characterization.

scholarly journals Synthesis and characterization of amphiphilic graft copolymers of poly(1,3 dioxolane) macromonomers with styrene and methyl methacrylate

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Hayet Bendaikha ◽  
Gérald Clisson ◽  
Abdelouahad Khoukh ◽  
Jeanne François ◽  
Seghier Ould Kada
Keyword(s):  
Methyl Methacrylate ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Molecular Weights ◽  
Molar Ratios ◽  
H Nmr ◽  
Amphiphilic Graft Copolymers ◽  
Exclusion Chromatography ◽  
Cationic Ring Opening Polymerization

AbstractMethacrylate-terminated Poly(1,3 dioxolane) (PDXL) macromonomers were synthesized by cationic ring-opening polymerization in the presence of 2- hydroxypropyl methacrylate (2-HPMA) as transfer agent. Molecular weights, polydispersity index and functionality of the PDXL macromonomers were evaluated by size exclusion chromatography (SEC) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). Copolymerizations of PDXL macromonomers, of different molecular weights, with styrene (St) and methyl methacrylate (MMA) were carried out using various feed molar ratios. The resulting polymers confirmed the grafting of PDXL with PS and PMMA by SEC and 1H-NMR Monomer reactivity ratios between the macromonomers and the comonomers were estimated from the copolymerization results. Macromonomer reactivity depends on the comonomer considered. Glass transition temperatures of the copolymers were found to decrease with an increase in the amount of PDXL in the copolymers. The values of Tg depend on the composition and the size of the PDXL grafts.

Synthesis and characterization of new liquid, branched and random poly(methylhydrosiloxanes)

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Jerzy Chruściel ◽  
Marzena Fejdyś ◽  
Zofia Michalska ◽  
Witold Fortuniak
Keyword(s):  
Vacuum Distillation ◽  
Size Exclusion ◽  
Synthesis And Characterization ◽  
Low Molecular Weight ◽  
Structural Units ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Random Structures ◽  
Ft Ir

AbstractTwelve new liquid branched poly(methylhydrosiloxanes) of random structures (b-r-PMHS), containing triple branching units MeSiO1.5 (T), both Me2SiO (D) and MeHSiO (DH) chain building units (or only mers MeHSiO), and terminal groups Me3SiO0.5, have been prepared by hydrolytic polycondensation method of appropriate organic chlorosilanes in diethyl ether medium at temperatures < 0 °C. Two b-r-PMHS containing structural units: M, D, DH, T and TH have been obtained as well. Volatile low molecular weight oligosiloxanes were removed by vacuum distillation at 125-150 °C. Yields of b-r-PMHS ranged from 57 to 84 wt. %. All polymeric products were characterized by FT-IR, 1H- and 29Si-NMR, and elemental analysis. Their dynamic viscosities were determined in the Brookfield HBDV+IIcP cone-plate viscometer. The molecular weights of b-r-PMHS and polydispersities of MW were analyzed by size exclusion chromatography (SEC).

Molecular Weight Characterization of Food Grade Polyethylenes and Extractables by Size Exclusion Chromatography

1981 ◽  
Vol 64 (4) ◽  
pp. 1008-1013
Author(s):  
Roger C Snyder ◽  
Charles V Breder
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
High Density ◽  
Size Exclusion ◽  
Low Density ◽  
Food Grade ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Band Spreading

Abstract Size exclusion chromatography (SEC) was used to characterize the molecular weight distribution (MWD) of 6 low density and 6 high density food grade polyethylene resins. The hexane and xylene extractable fractions of these 12 resins were also analyzed by SEC. An IBM 370/168 computer with an APL program was used to analyze the chromatograms and correct for chromatographic band spreading and skewing. Calculated weight average molecular weights (Mw) for the resins ranged from 40 000 to 200 000 and number average molecular weights (Mn) ranged from 6000 to 60 000. Median values of Mw and Mn were 1800 and 950, respectively, for hexane extractables from the low density resins, and were 310 and 290, respectively, for hexane extractables from the high density resins. Corresponding Mw and Mn values for xylene extractables were consistently larger than those for hexane extractables.

scholarly journals Polymers of ε-Caprolactone Using New Copper(II) and Zinc(II) Complexes as Initiators: Synthesis, Characterization and X-Ray Crystal Structures

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1239 ◽  
Author(s):  
Andrés Posada ◽  
Mario Macías ◽  
Santiago Movilla ◽  
Gian Miscione ◽  
León Pérez ◽  
...  
Keyword(s):  
Single Crystal ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Nmr Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Weights ◽  
Full Characterization ◽  
Solvent Free Conditions

Five of six new Zn(II) and Cu(II) complexes were active in the ring-opening polymerization (ROP) of ε-caprolactone (CL) under solvent-free conditions, producing polycaprolactones (PCLs) of high crystallinity with molecular weights between 22,900 and 38,700 g mol−1 and decomposition temperatures above 260 °C. 1H NMR analysis demonstrated that the PCLs obtained were mainly linear, having hydroxymethylene groups at the chain ends. The results obtained indicated a significant improvement in terms of the ratio of monomer:initiator compared to related Cu(II) and Zn(II) complexes. In addition, the structures of the complexes 1 and 4 were determined by single-crystal X-ray diffraction. The synthesis and full characterization of all complexes are described in this paper.

scholarly journals New G-Quadruplex-Forming Oligodeoxynucleotides Incorporating a Bifunctional Double-Ended Linker (DEL): Effects of DEL Size and ODNs Orientation on the Topology, Stability, and Molecularity of DEL-G-Quadruplexes

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 654 ◽  
Author(s):  
Maria Marzano ◽  
Andrea Falanga ◽  
Stefano D’Errico ◽  
Brunella Pinto ◽  
Giovanni Roviello ◽  
...  
Keyword(s):  
Size Exclusion Chromatography ◽  
Structural Characterization ◽  
Size Exclusion ◽  
Biological Processes ◽  
Dna Nanostructures ◽  
Nmr Studies ◽  
Molecular Weights ◽  
G Quadruplex ◽  
Exclusion Chromatography

G-quadruplexes (G4s) are unusual secondary structures of DNA occurring in guanosine-rich oligodeoxynucleotide (ODN) strands that are extensively studied for their relevance to the biological processes in which they are involved. In this study, we report the synthesis of a new kind of G4-forming molecule named double-ended-linker ODN (DEL-ODN), in which two TG4T strands are attached to the two ends of symmetric, non-nucleotide linkers. Four DEL-ODNs differing for the incorporation of either a short or long linker and the directionality of the TG4T strands were synthesized, and their ability to form G4 structures and/or multimeric species was investigated by PAGE, HPLC–size-exclusion chromatography (HPLC–SEC), circular dichroism (CD), and NMR studies in comparison with the previously reported monomeric tetra-ended-linker (TEL) analogues and with the corresponding tetramolecular species (TG4T)4. The structural characterization of DEL-ODNs confirmed the formation of stable, bimolecular DEL-G4s for all DEL-ODNs, as well as of additional DEL-G4 multimers with higher molecular weights, thus suggesting a way towards the obtainment of thermally stable DNA nanostructures based on reticulated DEL-G4s.

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