scholarly journals Random and Diblock Thermoresponsive Oligo(ethylene glycol)-Based Copolymers Synthesized via Photo-Induced RAFT Polymerization

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 137
Author(s):  
Alexey Sivokhin ◽  
Dmitry Orekhov ◽  
Oleg Kazantsev ◽  
Olga Sivokhina ◽  
Sergey Orekhov ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Room Temperature ◽  
Raft Polymerization ◽  
Chain Extension ◽  
Random Copolymers ◽  
Hydrophobic Core ◽  
Polymer Backbone ◽  
Alkyl Groups ◽  
Green Led ◽  
A Chain

Amphiphilic random and diblock thermoresponsive oligo(ethylene glycol)-based (co)polymers were synthesized via photoiniferter polymerization under visible light using trithiocarbonate as a chain transfer agent. The effect of solvent, light intensity and wavelength on the rate of the process was investigated. It was shown that blue and green LED light could initiate RAFT polymerization of macromonomers without an exogenous initiator at room temperature, giving bottlebrush polymers with low dispersity at sufficiently high conversions achieved in 1–2 h. The pseudo-living mechanism of polymerization and high chain-end fidelity were confirmed by successful chain extension. Thermoresponsive properties of the copolymers in aqueous solutions were studied via turbidimetry and laser light scattering. Random copolymers of methoxy- and alkoxy oligo(ethylene glycol) methacrylates of a specified length formed unimolecular micelles in water with a hydrophobic core consisting of a polymer backbone and alkyl groups and a hydrophilic oligo(ethylene glycol) shell. In contrast, the diblock copolymer formed huge multimolecular micelles.

Deprotective activity of nanosized globular partially quaternized poly(tertiary amine)s in peptide synthesis

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Pascal Chapon ◽  
Jean Coudane ◽  
Henri Garreau ◽  
Michel Vert ◽  
Jean Alain Ferhentz ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Aqueous Medium ◽  
Room Temperature ◽  
Heterogeneous Systems ◽  
Protecting Groups ◽  
Hydrophobic Core ◽  
Poly Ethylene Glycol ◽  
Solid Supports ◽  
Spacer Arm ◽  
Poly Ethylene

AbstractBifunctional polybases of the partially quaternized poly[thio-1-(N,Ndiethylaminomethyl) ethylene] type (Q(PTDAE),X, with X = percentage of N-quaternization) are able to catalyze various reactions including lipophilic reagents temporarily entrapped in the hydrophobic core of the globules. In this contribution it is shown that benzyloxycarbonyl (Z) and fluoromethyloxycarbonyl (Fmoc) protecting groups of peptides are cleaved at room temperature in a few minutes in an aqueous medium at pH 7,4. Deprotection was also effective when peptides were attached to solid supports of the Merrifield type provided a hydrophilic spacer arm of the poly(ethylene glycol)-type was inserted between beads and the built up peptide moieties. However, unhooking was observed when the hydrophilic spacerpeptide bond was an ester but not when it was of the amide type. The work shows that Q(PTDAE),X globules exhibit enzyme-like activity in a homogeneous aqueous medium and in heterogeneous systems as well.

scholarly journals Thermoresponsive Polymers of Poly(2-(N-alkylacrylamide)ethyl acetate)s

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2464
Author(s):  
Xue Liu ◽  
Yuwen Hou ◽  
Yimin Zhang ◽  
Wangqing Zhang
Keyword(s):  
Ethyl Acetate ◽  
Raft Polymerization ◽  
Polymer Concentration ◽  
Degree Of Polymerization ◽  
Random Copolymers ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Induction Periods ◽  
Alkyl Groups ◽  
Cloud Point Temperature

Thermoresponsive poly(2-(N-alkylacrylamide) ethyl acetate)s with different N-alkyl groups, including poly(2-(N-methylacrylamide) ethyl acetate) (PNMAAEA), poly(2-(N-ethylacrylamide) ethyl acetate) (PNEAAEA), and poly(2-(N-propylacrylamide) ethyl acetate) (PNPAAEA), as well as poly(N-acetoxylethylacrylamide) (PNAEAA), were synthesized by solution RAFT polymerization. Unexpectedly, it was found that there are induction periods in the RAFT polymerization of these monomers, and the induction time correlates with the length of the N-alkyl groups in the monomers and follows the order of NAEAA < NMAAEA < NEAAEA < NPAAEA. The solubility of poly(2-(N-alkylacrylamide) ethyl acetate)s in water is also firmly dependent on the length of the N-alkyl groups. PNPAAEA including the largest N-propyl group is insoluble in water, whereas PNMAAEA and PNEAAEA are thermoresponsive in water and undergo the reversible soluble-to-insoluble transition at a critical solution temperature. The cloud point temperature (Tcp) of the thermoresponsive polymers is in the order of PNEAAEA < PNAEAA < PNMAAEA. The parameters affecting the Tcp of thermoresponsive polymers, e.g., degree of polymerization (DP), polymer concentration, salt, urea, and phenol, are investigated. Thermoresponsive PNMAAEA-b-PNEAAEA block copolymer and PNMAAEA-co-PNEAAEA random copolymers with different PNMAAEA and/or PNEAAEA fractions are synthesized, and their thermoresponse is checked.

scholarly journals Hyperbranched Polycaprolactone through RAFT Polymerization of 2-Methylene-1,3-dioxepane

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 318 ◽  
Author(s):  
Ping Xu ◽  
Xiaofei Huang ◽  
Xiangqiang Pan ◽  
Na Li ◽  
Jian Zhu ◽  
...  
Keyword(s):  
Chain Transfer ◽  
Raft Polymerization ◽  
Gel Permeation Chromatography ◽  
Chain Extension ◽  
Polymer Composition ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Radical Ring ◽  
Polymer Backbone ◽  
Controlled Structure

Hyperbranched polycaprolactone with controlled structure was synthesized by reversible addition-fragmentation chain transfer radical ring-opening polymerization along with self-condensed vinyl polymerization (SCVP) of 2-methylene-1,3-dioxepane (MDO). Vinyl 2-[(ethoxycarbonothioyl) sulfanyl] propanoate (ECTVP) was used as polymerizable chain transfer agent. Living polymerization behavior was proved via pseudo linear kinetics, the molecular weight of polymers increasing with conversion and successful chain extension. The structure of polymers was characterized by 1H NMR spectroscopy, tripe detection gel permeation chromatography, and differential scanning calorimetry. The polymer composition was shown to be able to tune to vary the amount of ester repeat units in the polymer backbone, and hence determine the degree of branching. As expected, the degree of crystallinity was lower and the rate of degradation was faster in cases of increasing the number of branches.

scholarly journals Synthesis of Network Polymers by Means of Addition Reactions of Multifunctional-Amine and Poly(ethylene glycol) Diglycidyl Ether or Diacrylate Compounds

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2047
Author(s):  
Naofumi Naga ◽  
Mitsusuke Sato ◽  
Kensuke Mori ◽  
Hassan Nageh ◽  
Tamaki Nakano
Keyword(s):  
Ethylene Glycol ◽  
Room Temperature ◽  
Addition Reaction ◽  
Monomer Concentration ◽  
Diglycidyl Ether ◽  
Porous Polymers ◽  
Addition Reactions ◽  
Poly Ethylene Glycol ◽  
Network Polymers ◽  
Poly Ethylene

Addition reactions of multi-functional amine, polyethylene imine (PEI) or diethylenetriamine (DETA), and poly(ethylene glycol) diglycidyl ether (PEGDE) or poly(ethylene glycol) diacrylate (PEGDA), have been investigated to obtain network polymers in H2O, dimethyl sulfoxide (DMSO), and ethanol (EtOH). Ring opening addition reaction of the multi-functional amine and PEGDE in H2O at room temperature or in DMSO at 90 °C using triphenylphosphine as a catalyst yielded gels. Aza-Michael addition reaction of the multi-functional amine and PEGDA in DMSO or EtOH at room temperature also yielded corresponding gels. Compression test of the gels obtained with PEI showed higher Young’s modulus than those with DETA. The reactions of the multi-functional amine and low molecular weight PEGDA in EtOH under the specific conditions yielded porous polymers induced by phase separation during the network formation. The morphology of the porous polymers could be controlled by the reaction conditions, especially monomer concentration and feed ratio of the multi-functional amine to PEGDA of the reaction system. The porous structure was formed by connected spheres or a co-continuous monolithic structure. The porous polymers were unbreakable by compression, and their Young’s modulus increased with the increase in the monomer concentration of the reaction systems. The porous polymers absorbed various solvents derived from high affinity between the polyethylene glycol units in the network structure and the solvents.

The effects of osmotic pressure changes on the germination of Dictyostelium discoideum spores

1977 ◽  
Vol 23 (9) ◽  
pp. 1170-1177 ◽  
Author(s):  
David A. Cotter
Keyword(s):  
Ethylene Glycol ◽  
Dictyostelium Discoideum ◽  
Room Temperature ◽  
Thermal Inactivation ◽  
Sucrose Concentration ◽  
Lag Phase ◽  
Activation Process ◽  
Sucrose Solutions ◽  
Spore Population ◽  
Pressure Changes

Polyalcohols such as ethylene glycol and glycerol at 3 M penetrate and activate spores of Dictyostelium discoideum incubated at room temperature. Higher concentrations of ethylene glycol result in lysis upon suspension of spores in dilute phosphate buffer. Erythritol and arabitol at 3 M do not penetrate or activate D. discoideum spores.Air-dried spores or those incubated in 2 M sucrose solutions are not activated with the usual heat treatment of 45 °C for 30 min. The plasmolyzed spores are activated at temperatures above 45 °C when heated in the presence of 2 M sucrose for 30 min. The temperature for maximum activation and the temperature for thermal inactivation of spores are raised 7–10 °C in high sucrose concentrations. Long-term incubation of heat-activated spores in 2 M sucrose solutions does not result in a return to dormancy.Moderate sucrose concentrations near 0.2 M do not block the heat-induced activation process but must be removed from the spore population to prevent a return to dormancy within 6 h. Other polyhydric compounds at 0.25 M concentration also cause spore deactivation within 6 h of room temperature incubation. Oxygen uptake of spores undergoing deactivation in 0.18 M sucrose is inhibited as compared to control levels. Moderate concentrations of sucrose do not block the early events of postactivation lag and the spores accumulate at the end of the lag phase. The longer the spores remain unswollen at the end of the postactivation lag phase, the greater the percentage of spores which return to dormancy. The effects of moderate sucrose concentration (lowered water activity) are not duplicated by the same quantity of Ficoll, indicating that the colligative properties of the sucrose solutions are responsible for deactivation.

scholarly journals Iodination of insulin in aqueous and organic solvents

1969 ◽  
Vol 115 (1) ◽  
pp. 11-18 ◽  
Author(s):  
A. Massaglia ◽  
U. Rosa ◽  
G. Rialdi ◽  
C. A. Rossi
Keyword(s):  
Ethylene Glycol ◽  
Organic Solvents ◽  
Molecular Conformation ◽  
Aqueous Media ◽  
Native Structure ◽  
Experimental Conditions ◽  
Polar Environment ◽  
Polar Area ◽  
The Difference ◽  
A Chain

1. The iodination of insulin was studied under various experimental conditions in aqueous media and in some organic solvents, by measuring separately the uptake of iodine by the four tyrosyl groups and the relative amounts of monoiodotyrosine and di-iodotyrosine that are formed. In aqueous media from pH1 to pH9 the iodination occurs predominantly on the tyrosyl groups of the A chain. Some organic solvents increase the iodine uptake of the B-chain tyrosyl groups. Their efficacy in promoting iodination of Tyr-B-16 and Tyr-B-26 is in the order: ethylene glycol and propylene glycol≃methanol and ethanol>dioxan>8m-urea. 2. It is suggested that each of the four tyrosyl groups in insulin has a different environment: Tyr-A-14 is fully exposed to the solvent; Tyr-A-19 is sterically influenced by the environmental structure, possibly by the vicinity of a disulphide interchain bond; Tyr-B-16 is embedded into a non-polar area whose stability is virtually independent of the molecular conformation; Tyr-B-26 is probably in a situation similar to Tyr-B-16 with the difference that its non-polar environment depends on the preservation of the native structure.

scholarly journals Synthesis of polylactic acid-diol (PLA-diol) from lactic acid and 1,4-butanediol

2016 ◽  
Vol 19 (4) ◽  
pp. 58-65
Author(s):  
Ha Thi Thai La
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Polyethylene Glycol ◽  
1H Nmr ◽  
Biodegradable Polymer ◽  
Average Molecular Weight ◽  
Chain Extension ◽  
Structure And Properties ◽  
Chain Reaction ◽  
A Chain

In this research, the PLA-diol were synthesized from lactic acid (LA) and 1.4 butanediols (BD) with a tin octoate Sn(Oct)2 catalyst at a temperature of 180 °C and the pressure 5 mmHg. The structure and properties of PLA-diol are analyzed by the following methods: GPC, 1H-NMR and DSC. As a result, with the change in the content of Sn (Oct)2 from 0.1 to 1.0%, the molecular weight Mn of PLA - diol increased gradually from 4.119,2 to 7.359,6 g / mol . In addition, the BD content increased from 2.0% to 5.0%, the average molecular weight of the product decreased gradually from 7.536,9 g / mol to 4.735 g / mol, respectively. This change will affect the ability to use PLA-diol in the next denaturation research to apply in the field of biodegradable polymer such as copolymer with polyurethane, copolymer with polyethylene glycol diacid, or chain extension with other polymer in a chain reaction,...

Synthesis of Well-defined Carbazole Group Labelled Polymer via RAFT Polymerization and Study on the Optical Properties

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Di Zhou ◽  
Xiulin Zhu ◽  
Jian Zhu ◽  
Lihua Hu ◽  
Zhenping Cheng
Keyword(s):  
Optical Properties ◽  
Raft Polymerization ◽  
Chain Extension ◽  
Dimethyl Formamide ◽  
Coupling Scheme ◽  
H Nmr ◽  
Azo Polymer ◽  
Raft Agent ◽  
Carbazole Group ◽  
Polymerization Conditions

AbstractBenzyl 9H-carbazole-9-carbodithioate (BCC) was synthesized and characterized. The single-crystal structure of BCC was first reported. The RAFT polymerizations of styrene and acrylates using BCC as the RAFT agent under conventional polymerization conditions were investigated. The results showed that the BCC was an effective RAFT agent for the polymerizations of styrene and acrylates. The well-controlled polymers were labelled with carbazole group, which was confirmed by 1H NMR and the chain extension of the obtained polymer. Azo modified poly(methyl acrylate) (PMA) was synthesized through a postpolymerization azo-coupling scheme. The optical properties of obtained polymer were also characterized. The results showed that the carbazole group labelled polymer exhibited fluorescence and the azo polymer exhibited UV absorption behaviour in N,N-dimethyl formamide (DMF).

Sign in / Sign up

Export Citation Format

Share Document