scholarly journals From nano-emulsions to phase separation: evidence of nano-segregation in (alkane + perfluoroalkane) mixtures using 129Xe NMR Spectroscopy

2019 ◽  
Vol 21 (7) ◽  
pp. 3742-3751 ◽  
Author(s):  
Pedro Morgado ◽  
Luís F. G. Martins ◽  
Eduardo J. M. Filipe
Keyword(s):  
Phase Separation ◽  
Nmr Spectroscopy ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
129Xe Nmr ◽  
Upper Critical Solution Temperature

In this work we demonstrate that mixtures of (hexane + perfluorohexane) above the upper critical solution temperature segregate by forming domains at the nanometric scale.

Thermodynamic analysis of phase separation of a thermoplastic in a variant epoxy/monoamine-diamine system: influence of epoxy molecular structure

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Joaquin Lopez ◽  
Maite Rico ◽  
Belen Montero ◽  
Carmen Ramirez
Keyword(s):  
Molecular Structure ◽  
Phase Separation ◽  
Polymerization Process ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Crosslinked Polymer ◽  
Epoxy Amine ◽  
Upper Critical Solution Temperature ◽  
Amine System ◽  
Molecular Fractionation

Abstract A thermodynamic study of phase separation induced by the polymerization process was carried out in a variant epoxy/amine system modified with polystyrene (PS) by means of a model based on the Flory-Huggins theory in which the polydispersity of components was taken into account. Modification of the epoxy/amine system was to continually change its molecular structure from a linear polymer to a highly crosslinked polymer using a monoamine and a diamine mixed in different proportions. The cloud-point curves during polymerization for five epoxy/monoamine-diamine systems with PS blends were experimentally measured. Application of the thermodynamic model led to obtaining the corresponding phase diagrams. All studied blends showed an upper critical solution temperature behavior and an increase in miscibility was observed by increasing the monoamine/diamine ratio. The polydispersity of components caused a molecular fractionation leading to a difference in the conversion of separate phases.

scholarly journals Aqueous Liquid-Liquid Phase Separation of Natural and Synthetic Polyguanidiniums

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 649 ◽  
Author(s):  
Prather ◽  
Weerasekare ◽  
Sima ◽  
Quinn ◽  
Stewart
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Liquid Phase Separation ◽  
Solution Temperature ◽  
Titration Calorimetry ◽  
Polymer Backbone ◽  
Critical Solution Temperature ◽  
Upper Critical Solution Temperature ◽  
Positively Charged ◽  
Liquid Liquid Phase Separation

Protamines are natural polyguanidiniums, arginine(R)-rich proteins involved in the compaction of chromatin during vertebrate spermatogenesis. Salmine, a protamine isolated from salmon sperm, contains 65 mol% R residues, with positively charged guanidino (Gdm+) sidechains, and no other amino acids with ionizable or aromatic sidechains. Salmine sulfate solutions undergo liquid-liquid phase separation (LLPS) with a concentration-dependent upper critical solution temperature (UCST). The condensed liquid phase comprises 50 wt % water and >600 mg·ml−1 salmine with a constant 1:2 ratio of sulfate (SO42−) to Gdm+. Isothermal titration calorimetry, titrating Na2SO4 into salmine chloride above and below the UCST, allowed isolation of exothermic sulfate binding to salmine chloride from subsequent endothermic condensation and exothermic phase separation events. Synthetic random polyacrylate analogs of salmine, with 3-guanidinopropyl sidechains, displayed similar counterion dependent phase behavior, demonstrating that the LLPS of polyguanidiniums does not depend upon subunit sequence or polymer backbone chirality, and was due entirely to Gdm+ sidechain interactions. The results provide experimental evidence for like-charge pairing of Gdm+ sidechains, and an experimental approach for further characterizing these interactions.

scholarly journals Influence of cyclodextrin on the UCST- and LCST-behavior of poly(2-methacrylamido-caprolactam)-co-(N,N-dimethylacrylamide)

2014 ◽  
Vol 10 ◽  
pp. 1951-1958 ◽  
Author(s):  
Alexander Burkhart ◽  
Helmut Ritter
Keyword(s):  
Free Radical ◽  
Nmr Spectroscopy ◽  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Radical Mechanism ◽  
Methacryloyl Chloride ◽  
Critical Solution Temperature ◽  
Free Radical Mechanism ◽  
Upper Critical Solution Temperature ◽  
Lcst Behavior

The monomer 2-methacrylamido-caprolactam (4) was synthesized from methacryloyl chloride (3) and racemic α-amino-ε-caprolactam (2). Copolymerization of 4 with N,N-dimethylacrylamide (5) was carried out by a free-radical mechanism using 2,2’-azobis(2-methylpropionitrile) (AIBN) as an initiator. The new copolymers show a lower critical solution temperature (LCST) in water and an upper critical solution temperature (UCST) in ethanol, 1-propanol, and 1-butanol. The solubility properties of the copolymers can be influenced significantly by the addition of randomly methylated β-cyclodextrin (CD). The complexation of the copolymers with CD, was confirmed by the use of ROESY-NMR-spectroscopy.

scholarly journals Phase-Separation of Cellulose from Ionic Liquid upon Cooling: Preparation of Microsized Particles

2021 ◽  
Author(s):  
Jingwen Xia ◽  
Alistair W. T. King ◽  
Ilkka Kilpelainen ◽  
Vladimir Aseyev
Keyword(s):  
Ionic Liquid ◽  
Phase Separation ◽  
Electrolyte Solutions ◽  
Colloidal Dispersions ◽  
Fiber Spinning ◽  
Solution Temperature ◽  
Experimental Conditions ◽  
Critical Solution Temperature ◽  
Upper Critical Solution Temperature ◽  
Separation Temperature

Abstract Cellulose is an historical polymer, for which its processing possibilities have been limited by the absence of a melting point and insolubility in all non-derivatizing molecular solvents. More recently, ionic liquids (ILs) have been used for cellulose dissolution and regeneration, for example, in the development of textile fiber spinning processes. In some cases, organic electrolyte solutions (OESs), that are binary mixtures of an ionic liquid and a polar aprotic co-solvent, can show even better technical dissolution capacities for cellulose than the pure ILs. Herein we use OESs consisting of two tetraalkylphosphonium acetate ILs and dimethyl sulfoxide (DMSO) or γ-valerolactone (GVL), as co-solvents. Cellulose can be first dissolved in these OESs at 120°C and then regenerated, upon cooling, leading to micro and macro phase-separation. This phenomenon much resembles the upper-critical solution temperature (UCST) type thermodynamic transition. This observed UCST-like behavior of these systems allows for the controlled regeneration of cellulose into colloidal dispersions of spherical microscale particles (spherulites), with highly ordered shape and size. While this phenomenon has been reported for other IL and NMMO-based systems, the mechanisms and phase-behavior have not been well defined. The particles are obtained below the phase-separation temperature as a result of controlled multi-molecular association. The regeneration process is a consequence of multi-parameter interdependence, where the polymer characteristics, OES composition, temperature, cooling rate and time all play their roles. The influence of the experimental conditions, cellulose concentration and the effect of time on regeneration of cellulose in the form of preferential gel or particles is discussed.Regular micro-sized particles regenerated from a cellulose-OES mixture of tetrabutylphosphonium acetate:DMSO (70:30 w/w） upon cooling.

scholarly journals Phase-separation of cellulose from ionic liquid upon cooling: preparation of microsized particles

Cellulose ◽  
2021 ◽  
Author(s):  
Jingwen Xia ◽  
Alistair W. T. King ◽  
Ilkka Kilpeläinen ◽  
Vladimir Aseyev
Keyword(s):  
Ionic Liquid ◽  
Phase Separation ◽  
Electrolyte Solutions ◽  
Colloidal Dispersions ◽  
Fiber Spinning ◽  
Solution Temperature ◽  
Experimental Conditions ◽  
Critical Solution Temperature ◽  
Upper Critical Solution Temperature ◽  
Separation Temperature

Abstract Cellulose is an historical polymer, for which its processing possibilities have been limited by the absence of a melting point and insolubility in all non-derivatizing molecular solvents. More recently, ionic liquids (ILs) have been used for cellulose dissolution and regeneration, for example, in the development of textile fiber spinning processes. In some cases, organic electrolyte solutions (OESs), that are binary mixtures of an ionic liquid and a polar aprotic co-solvent, can show even better technical dissolution capacities for cellulose than the pure ILs. Herein we use OESs consisting of two tetraalkylphosphonium acetate ILs and dimethyl sulfoxide or γ-valerolactone, as co-solvents. Cellulose can be first dissolved in these OESs at 120 °C and then regenerated, upon cooling, leading to micro and macro phase-separation. This phenomenon much resembles the upper-critical solution temperature (UCST) type thermodynamic transition. This observed UCST-like behavior of these systems allows for the controlled regeneration of cellulose into colloidal dispersions of spherical microscale particles (spherulites), with highly ordered shape and size. While this phenomenon has been reported for other IL and NMMO-based systems, the mechanisms and phase-behavior have not been well defined. The particles are obtained below the phase-separation temperature as a result of controlled multi-molecular association. The regeneration process is a consequence of multi-parameter interdependence, where the polymer characteristics, OES composition, temperature, cooling rate and time all play their roles. The influence of the experimental conditions, cellulose concentration and the effect of time on regeneration of cellulose in the form of preferential gel or particles is discussed. Graphical abstract Regular micro-sized particles regenerated from a cellulose-OES mixture of tetrabutylphosphonium acetate:DMSO (70:30 w/w) upon cooling

Rheology and phase separation in a model upper critical solution temperature polymer blend

1997 ◽  
Vol 41 (3) ◽  
pp. 739-755 ◽  
Author(s):  
D. Vlassopoulos ◽  
A. Koumoutsakos ◽  
S. H. Anastasiadis ◽  
S. G. Hatzikiriakos ◽  
P. Englezos
Keyword(s):  
Phase Separation ◽  
Polymer Blend ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Upper Critical Solution Temperature

Selective Hydrogen Bonding Controls Temperature Response of Layer-by-Layer Upper Critical Solution Temperature Micellar Assemblies

Soft Matter ◽  
2021 ◽  
Author(s):  
Aliaksei Aliakseyeu ◽  
Victoria Albright ◽  
Danielle Yarbrough ◽  
Samantha Hernandez ◽  
Qing Zhou ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Methacrylic Acid ◽  
Temperature Response ◽  
Solution Temperature ◽  
Layer By Layer ◽  
Critical Solution Temperature ◽  
Hydrogen Bonding Interactions ◽  
Upper Critical Solution Temperature ◽  
Lbl Films

This work establishes a correlation between the selectivity of hydrogen-bonding interactions and the functionality of micelle-containing layer-by-layer (LbL) assemblies. Specifically, we explore LbL films formed by assembly of poly(methacrylic acid)...

Sign in / Sign up

Export Citation Format

Share Document