Ring-opening Polymerization Approach Research Articles

Degradable N-Vinyl Copolymers through Radical Ring-Opening Polymerization of Cyclic Thionocarbamates.

A thiocarbonyl radical ring-opening polymerization approach was implemented with cyclic thionocarbamates to generate degradable copolymers with N-vinyl monomers. The rigid structures of cyclic N-substituted thionocarbamates have been revealed by X-ray crystallography and NMR spectroscopy. The corresponding copolymers show incorporation of the thiocarbamates within the carbon backbone of polyvinylpyrrolidone influenced by acyl substituents through radical ring-opening copolymerization. The phenyl-substituted cyclic thionocarbamate copolymerized with N-vinyl carbazole and N-vinyl caprolactam, while little to no incorporation occurred with tBu acrylate and styrene, respectively. Further, these copolymers can undergo hydrolytic degradation under mild conditions. A new family of cyclic thionocarbamates capable of radical ring-opening copolymerization with N-vinyl monomers has been established.

Aliphatic Hyperbranched Polycarbonates Solid Polymer Electrolytes with High Li-Ion Transference Number for Lithium Metal Batteries.

In this work, hyperbranched polycarbonate-poly(ethylene oxide) (PEO)-based solid polymer electrolytes (HBPC-SEs) are successfully synthesized via a straightforward organo-catalyzed "A1"+"B2"-ring-opening polymerization approach. The temperature-dependent ionic conductivity of HBPC-SEs, composed of different polycarbonate linkages and various LiTFSI concentrations, is investigated. The results demonstrate that HBPC-SE with an ether-carbonate alternating structure exhibits superior ionic conductivity, attributed to the solubility of Li salts in the polymer matrix and the mobility of the polymer segments. The HBPC1-SE with 30 wt% LiTFSI presents the highest ionic conductivities of 2.15 × 10-5, 1.78 × 10-4, and 6.07 × 10-4 Scm-1 at 30, 60, and 80 °C, respectively. Compared to traditional PEO-based electrolytes, the incorporation of polycarbonate segments significantly enhances the electrochemical stability window (5V) and Li+ transference number (0.53) of HBPC-SEs. Furthermore, the LiFePO4/HBPC1-SE-3/Li cell exhibits exceptional rate capability and long-cycling performance, maintaining a discharge capacity of 130 mAh g-1 at 0.5C with a capacity retention of 95% after 300 cycles.

Preparation of COOH-KCC-1/polyamide 6 composite by in situ ring-opening polymerization: synthesis, characterization, and Cd(II) adsorption study

A nanocomposite of carboxylic acid-functionalized fibrous silica KCC-1 and polyamide 6 (COOH-KCC-1/PA6 NC) was fabricated through an ultrasonic-assisted in situ ring-opening polymerization approach under an organic solvent-free condition. The presence of abundant functional groups like carboxylic, secondary amine, and ketone in the COOH-KCC-1/PA6 NC structure can make it a good candidate for the adsorption of heavy metals. Accordingly, COOH-KCC-1/PA6 NC was characterized and utilized as an adsorbent for Cd(II) uptake from aqueous media. Crucial adsorption factors, namely pH, adsorbent dosage, Cd(II) initial concentration, and contact time, affecting the removal of Cd(II) were monitored and the optimum adsorption conditions were determined. Isotherm and kinetic investigations were conducted and a non-linear fitting method of experimental data was used to obtain isotherm and kinetic parameters. The experimental maximum adsorption capacity of Cd(II) was found to be 109.2 mg g–1 (pH: 7.0, adsorbent dosage: 0.05 g, initial concentration: 80 mg L–1, time: 240 min, temperature: 25 ℃). The observed adsorption property is due to (1) the uniform distribution of COOH-KCC-1 filler within the PA6 matrix, (2) the presence of abundant adsorption sites like carboxylic acid (−COOH), ketone (–C=O), silanol (Si−OH), and secondary amine (–NH–) in the adsorbent structure, and (3) the structural stability of the adsorbent owing to strong interfacial interactions (physical and chemical bonding) between COOH-KCC-1 and PA6 polymer. Based on the results it can be suggested that the COOH-KCC-1/PA6 NC adsorbent can be handled for the adsorption of Cd(II) from aqueous media.

An organocatalytic ring-opening polymerization approach to highly alternating copolymers of lactic acid and glycolic acid

Highly regioselective ring-opening polymerization of optically active methylglycolides was achived using P2-t-Bu/alcohol system to produce alternating copolymer of lactic acid and glycolic acid.

Radical Cascade-Triggered Controlled Ring-Opening Polymerization of Macrocyclic Monomers.

A strategy for the controlled radical ring-opening polymerization of macrocyclic monomers is reported. Key to this approach is an allyl alkylsulfone-based ring-opening trigger that can undergo a radical cascade reaction to extrude sulfur dioxide and generate an alkyl radical for controlled chain propagation. A systematic study correlating reaction conditions with polymer molecular weight and molecular weight distribution allowed excellent control over polymerization. The versatility of this radical cascade-triggered ring-opening polymerization approach was further demonstrated through the first radical block copolymerization of macrocyclic monomers, and the incorporation of degradable functionality into the polymer backbone.

Surface functionalization of graphene oxide with poly(2-hydroxyethyl methacrylate)-graft-poly(ε-caprolactone) and its electrospun nanofibers with gelatin

This article describes covalent functionalization of graphene oxide (GO) with poly(2-hydroxyethyl methacrylate)-graft-poly(e-caprolactone) [P(HEMA-g-CL)] via ‘living’ polymerization techniques and preparation of its electrospun nanofibers with gelatin. For this purpose, the GO was synthesized by oxidizing pristine graphite powder and then acetyl chloride was incorporated into the GO to afford an atom transfer radical polymerization (ATRP) macroinitiator (GO-Cl). The synthesized macroinitiator was employed for HEMA polymerization via ATRP technique to produce GO-g-PHEMA. Afterward, CL was graft copolymerized from the hydroxyl groups of the PHEMA via ring-opening polymerization approach to afford GO-g-[P(HEMA-g-CL)] nanocomposite. The solutions of the GO-g-[P(HEMA-g-CL)] and gelatin were electrospun to fabricate uniform, conductive, and biocompatible nanofibers. The morphology, in vitro degradability, biocompatibility, hydrophilicity, and conductivity of the GO-g-[P(HEMA-g-CL)]/gelatin electrospun nanofibers were investigated. It is expected that the prepared nanofibers find application as a scaffolding biomaterial for regenerative medicine, mainly due to their biocompatibility, degradability, and electrical conductivity.

Poly(ε-caprolactone)-Grafted Fe3O4 Nanoparticles: Preparation and Superparamagnetic Nanocomposites with Epoxy Thermosets

Poly(ε-caprolactone)-grafted magnetic iron oxide nanoparticles (Fe3O4 NPs) were prepared via a surface-initiated ring opening polymerization approach. First, the surface of the unmodified Fe3O4 NPs were treated with 3-aminopropyltriethoxysilane to afford the 3-aminopropyl-functionalzed Fe3O4 NPs. Second, the surface-initiated ring-opening polymerization of ε-caprolactone was carried out with the surface-functionalized Fe3O4 NPs as the initiator to afford the poly(ε-caprolactone)(PCL)-grafted Fe3O4 NPs. The PCL-grafted Fe3O4 NPs have been characterized by means of Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and transmission electron microscopy. It was found that the PCL-grafted Fe3O4 NPs can be well dispersed into epoxy thermosets. The nanocomposites were successfully obtained with the content of the PCL-grafted Fe3O4 NPs up to 40 wt %. The fine dispersion of Fe3O4 nanoparticles in epoxy was demonstrated by transmission electron microscopy and dynamic mechanical thermal analysis. The results of magnetic analysis with vibrating sample measuring technology indicated that the nanocomposites involving epoxy resins and Fe3O4 nanoparticles possessed superparamagnetic properties.

Anionic ring-opening polymerization for synthetic analogues of aliphatic biopolyesters

Recent developments and future trends regarding synthetic analogues of aliphatic biopolyesters are presented. Using anionic ring-opening polymerization approach, polyhydroxyalkanoate analogues with defined chemical structure of the end groups as well as block, graft and random copolymers have been obtained and characterized by various techniques with a special emphasis to mass spectrometry. The relationship between the structure, properties and function of the novel polymeric materials prepared is discussed.

Synthesis of 13C-Perlabeled Cellulose with more than 99% Isotopic Enrichment by a Cationic Ring-Opening Polymerization Approach

(13)C-Perlabeled cellulose was obtained in a seven-step approach from (13)C(6)-labeled d-glucose with a cationic ring-opening polymerization as the key step. Isopropylidene protection, benzylation of the remaining free 3-O-position and subsequent deprotection afforded 3-O-benzyl-(13)C(6)-glucose (2). Regioselective bis-pivaloylation followed by subsequent ortho-esterification provided the precursor for the cationic ring-opening polymerization, 3-O-benzyl-(13)C(6)-glucopyranose 1,2,4-orthopivalate (4). The actual polymerization step gave a stereo- and regioregular (13)C-perlabeled (1-->4)-beta-glucopyranan derivative, which was deprotected into fully labeled (13)C-cellulose, as the cellulose II allomorph with a DP of 40, in an overall 28% yield. All reaction steps were optimized beforehand with nonlabeled compounds toward high yields and high reproducibility and the final compound was comprehensively analytically characterized.

New Ground for Organic Catalysis: A Ring-Opening Polymerization Approach to Hydrogels

Herein, we describe an organocatalytic living polymerization approach to network and subsequent hydrogel formation. Cyclic carbonate-functionalized macromolecules were ring-opened using an alcoholic initiator in the presence of an organic catalyst, amidine 1,8-diazabicyclo[5.4.0]undec-7-ene. A model reaction for the cross-linking identified monomer concentration-dependent reaction regimes, and enhanced kinetic control was demonstrated by introducing a co-monomer, trimethylene carbonate. The addition of the co-monomer facilitated near-quantitative conversion of monomer to polymer (>96%). Resulting poly(ethylene glycol) networks swell significantly in water, and an open co-continuous (water-gel) porous structure was observed by scanning electron microscopy. The organocatalytic ring-opening polymerization of cyclic carbonate functional macromonomers using alcoholic initiators provides a simple, efficient, and versatile approach to hydrogel networks.

Preparation of multi-walled carbon nanotubes grafted with synthetic poly(l-lysine) through surface-initiated ring-opening polymerization

A surface-initiated ring-opening polymerization approach was used to functionalize multi-walled carbon nanotubes (MWNTs) with linear poly(l-lysine) (PLL). The oxidized MWNTs, which resulted from the treatment of MWNTs with mixed concentrated sulfuric acid and nitric acid, were converted into amino-functionalized MWNTs (MWNT-NH2) by the amidation of carboxylic group on MWNT surface with excess 1,6-diaminohexane. Surface-initiated ring-opening polymerization of ɛ-(benzyloxycarbonyl)-l-lysine N-carboxyanhydride with MWNT-NH2 as the initiator resulted in MWNTs grafted with poly(ɛ-(benzyloxycarbonyl)-l-lysine) (MWNT-g-PLys(Z)). After the acidolysis of benzylcarbamate group of the grafting poly(ɛ-(benzyloxycarbonyl)-l-lysine) chain, water-soluble MWNTs grafted with PLL (MWNT-g-PLL) were obtained. The successful grafting was confirmed by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, elemental analyses, high-resolution transmission electron microscopy (HRTEM) and field-emission scanning electron microscopy. HRTEM indicates that MWNTs were enveloped by PLL layer. The as-prepared MWNT-g-PLys(Z) and MWNT-g-PLL exhibited excellent ability to disperse homogeneously in THF and water, respectively.

New Aspects of the Preparation and Polymerization of Cl 3PNP(O)Cl 2

The DeJaeger synthesis of poly(dichlorophosphazene), (NPCl 2)n (1) from P-trichloro-N-(dichlorophosphoryl)monophosphazene, Cl 3P=NP(O)Cl 2 (2) represents an attractive alternative to the ring opening polymerization approach to 1. We have followed the Emsley reaction, i.e. PCl 5 and (NH4)2SO4, under a variety of conditions by 31P NMR spectroscopy. Alternative oxygen atom sources in place of (NH4)2SO4 were also explored. Model reactions to identify specific pathways potentially operating in the formation of 2 when combined with the NMR studies allow for identification of the most probable sequence of steps leading to 2. Conversion of 2 to 1 under different conditions was also examined. Molecular weight was monitored as a function of time by GPC with online direct detection of the diphenoxy derivative, [NP(OC6H5)2]n, of 1. The byproduct of the polymerization of 2 is POCl 3. After conversion of 2 to (RO)3PO, a one step process has been developed for conversion into (RO)3P=NSiMe3, another class of poly(phosphazene) precursors.