Ring-opening Polymerization Of Poly Research Articles

One-pot synthesis of amphiphilic multiblock poly(2-oxazoline)s via para-fluoro-thiol click reactions

A clickable initiator, pentafluoro benzyl bromide, has been investigated for the cationic ring opening polymerization of poly(2-oxazolines).

Enhanced thermal and mechanical properties of PLA/MoS2 nanocomposites synthesized via the in-situ ring-opening polymerization

In this work, MoS2 nanosheets were employed to reinforce PLA. In order to promote the homogeneous dispersion of MoS2 in PLA and form a strong interface between MoS2 and PLA, the MoS2 nanosheets were firstly modified by mercapto-ethylamine, and then functionalized with PLA chains through ring-opening polymerization of poly(l-lactide). The XRD, XPS, TGA and 1H NMR characterizations confirmed the successful amino and PLA functionalization of MoS2 nanosheets. The obtained MoS2-g-PLA nanosheets were then introduced to reinforce PLA. SEM images displayed that the MoS2-g-PLA nanosheets were dispersed in PLA matrix uniformly. TGA results showed that initial decomposition temperature was improved from 275.6 °C to 334.8 °C with 0.5 wt% of MoS2-g-PLA nanosheets. The storage modulus of PLA/MoS2-g-PLA-0.5 wt% in the glass state and rubber state were both greatly enhanced compared with neat PLA.

Effects of different reaction mediums on ring opening polymerization of poly(ε-caprolactone) by lipase

This work examined the effects of reaction conditions on ring opening polymerization of poly(ecaprolactone) (PCL) by Candida antarctica lipase B (Novozym 435) as the catalyst. Different reaction mediums were obtained by changing of temperature, reaction time and solvent types simultaneously. The main purpose of this study was to observe molecular weight distribution, conversion rates, and thermal behaviors of PCL and to find the highest molecular weight in enzymatic reaction conditions. Three different reaction temperatures and solvent types were studied in this work. Reactions were carried out at 40, 60 and 80°C and n-hexane, toluene and diisopropyl ether were used as solvents. One more reaction series were done for toluene solution at 30°C. Moreover, experiments were undertaken at seven different time periods. During all the reactions, monomer, solvent, and enzyme concentrations were not changed. For 1 ml monomer/solvent solution (0.44 M monomer and 0.56 M solvent), 10 mg lipase were used in the experiments. All samples were analyzed by gel permeation chromatography (GPC) and hydrogen nuclear magnetic resonance ( 1 H-NMR) to obtain molecular weights, conversion rates, and chemical structures. Fourier transform infrared spectroscopy (FTIR) analysis was performed to determine chain structures of PCL samples. Thermal behaviors of samples were analyzed by differential scanning calorimetry (DSC) to examine and compare polymers with each other.

Mathematical Modeling of the Poly(lactic acid) Ring-Opening Polymerization using Stannous Octoate as a Catalyst

A novel and simple mathematical model to get the polymerization rate constants for the ring-opening polymerization of poly(lactic acid) is described. The model permits evaluation of the degree of polymerization versus monomer-to-initiator ratio curves. The predicted results are compared with the reported experimental data. The value of rate constants for initiation, propagation, and different modes of termination, are also obtained.

Synthesis, characterization, and ring opening polymerization of poly(1,4-cyclohexylenedimethylene terephthalate) cyclic oligomers

Cyclic oligomers of poly(1,4-cyclohexylenedimethylene terephthalate) (PCT) were prepared by reaction of 1,4-cyclohexanedimethanol (CHDM) with tereph- thaloyl chloride under diluted conditions and separated from the linear products by silica gel column at a yield of 23.7 wt %. Cyclic dimer, trimer, tetramer, pentamer, and hexamer were further separated by high performance liquid chromatography, and found to constitute 98% of the cyclics mixtures. The structures of PCT cyclics were confirmed by means of mass spectrometry, Fourier transform infrared, and 1 H NMR analysis. A series of experiments were carried out to study the effects of catalysts and cis/trans configuration of isomers of CHDM on the yield of cyclic oligomers. Ring opening polymerization of the cyclic oligomers was carried out by heating the sample mixtures at 310 °C for 30 min in the presence of antimony oxide. Polymerization was confirmed by inherent viscosity changes and infrared spectra of the resulting polyes- ters. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1828 -1833, 2000

Synthesis and Ring-Opening Polymerization of Poly(alkylene 2,6-naphthalenedicarboxylate) Cyclic Oligomers

Cyclic oligomers of poly(ethylene 2,6-naphthalenedicarboxylate) (PEN) and poly(butylene 2,6-naphthalenedicarboxylate) (PBN) were prepared by reaction of 2,6-naphthalenedicarbonyl dichloride with the corresponding diol. The structures of the cyclic oligomers were confirmed by a combination of GPC, mass spectrometry, and NMR analysis. The PEN cyclics were obtained in 57% yield with a preponderance of the cyclic trimer. The PBN cyclics were obtained in 75% yield with a preponderance of the cyclic dimer. Ring-opening polymerization of either cyclic material was performed in the melt using either a tin or titanium catalyst. The inherent viscosity of PBN or PEN prepared via ring-opening polymerization was lower than that of commercial samples.