Phase Behavior and Heat Capacity of {DPnP + Water} Mixtures at the Temperature Range of 273.15–338.15 K

The differential scanning calorimetry method (DSC) was used to examine the miscibility in the{dipropylene glycol propyl ether (DPnP) + water}system. Based on recorded curves of differential heat flow on temperature, HF=f(T), the range (composition, temperature) of the occurrence of miscibility gap, the values of lower critical solution temperature (LCST), and critical concentration were determined. On the basis of the experimentally determined specific heat capacity data the partial molar heat capacities (Cp,2) of DPnP in the mixtures with water were calculated. Analyzing changes in the course ofCp,2=f(x2)function, the boundary of transition from a homogeneous solution was determined, in which the monomers of amphiphile dominate, to the region, in which aggregates of the cluster type appear.

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Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2016-0004 ◽

2016 ◽

Vol 2 (1) ◽

pp. 1-4

Author(s):

Sylvia Pfensig ◽

Daniela Arbeiter ◽

Klaus-Peter Schmitz ◽

Niels Grabow ◽

Thomas Eickner ◽

...

Keyword(s):

Mechanical Characterization ◽

Heating Temperature ◽

Controlled Drug Release ◽

Solution Temperature ◽

Scanning Calorimetry ◽

Critical Solution Temperature ◽

Temperature Range ◽

Hybrid Hydrogels ◽

Higher Temperature

AbstractIn this study, varying amounts of NIPAAm and an ionic liquid (IL), namely 1-vinyl-3-isopropylimidazolium bromide ([ViPrIm]+[Br]−), have been used to synthesize hybrid hydrogels by radical emulsion polymerization. Amounts of 70/30%, 50/50%, 30/70%, 15/85% and 5/95% (wt/wt) of PIL/pNIPAAm were used to produce hybrid hydrogels as well as the parental hydrogels. The adhesive strength was investigated and evaluated for mechanical characterization. Thermal properties of resulting hydrogels have been investigated using differential scanning calorimetry (DSC) in a default heating temperature range (heating rate 10 K min−1). The presence of poly ionic liquids (PIL) in the polymer matrix leads to a moved LCST (lower critical solution temperature) to a higher temperature range for certain hybrid hydrogels PIL/pNIPAAm. While pNIPAAm exhibits an LCST at 33.9 ± 0.3°C, PIL/pNIPAAm 5/95% and PIL/pNIPAAm 15/85% were found to have LCSTs at 37.6 ± 0.9°C and 52 ± 2°C, respectively. This could be used for controlled drug release that goes along with increasing body temperature in response to an implantation caused infection.

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Dielectric Constants of a Binary Solution Near the Critical Solution Temperature

Canadian Journal of Chemistry ◽

10.1139/v73-083 ◽

1973 ◽

Vol 51 (4) ◽

pp. 545-550 ◽

Cited By ~ 15

Author(s):

I. Lubezky ◽

R. McIntosh

Keyword(s):

High Frequency ◽

Binary Solution ◽

Critical Concentration ◽

Low Frequency ◽

Dielectric Constants ◽

Solution Temperature ◽

Dielectric Losses ◽

Theoretical Studies ◽

Critical Solution Temperature ◽

Experimental Knowledge

The dielectric constants and dielectric losses of solutions of nitrobenzene and 2,2,4-trimethyl pentane have been measured near the critical solution temperature over a concentration range of 22–75% by weight and in the frequency regions of 5–60 and 1000 – 4000 kHz. It was found that below a critical concentration of 35% maxima existed in ε′ and ε″ at a temperature of 0.3 °C above the critical solution temperature. At higher concentrations the maxima disappeared and phase separation was preceded only by changes in the thermal coefficients dε′/dT and dε″/dT. The present study combined with others indicates that two regions of loss exist for the system near the critical temperature: low frequency losses of a conductive nature and high frequency losses of the Debye type. The published experimental knowledge of such systems remains insufficient to enable a thorough test of the theoretical studies published recently by Snider.

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THERMOSENSITIVE NANOPARTICLES CONJUGATING WITH CD34 ANTIBODY AND ITS SOLUTION PEROPERTIES

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s101623720600035x ◽

2006 ◽

Vol 18 (05) ◽

pp. 222-228 ◽

Cited By ~ 1

Author(s):

CHUN-TE TAO ◽

TAI-HORNG YOUNG

Keyword(s):

Controlled Release ◽

Cloud Point ◽

Lower Critical Solution Temperature ◽

Homogeneous Solution ◽

The Body ◽

Solution Temperature ◽

Temperature Sensitive ◽

Critical Solution Temperature ◽

Human Cd34 ◽

Collapse Temperature

Poly N-isopropylacrylamide (PNIPAAm) is a well-known temperature-sensitive polymer. When the temperature is higher than the lower critical solution temperature (LCST), PNIPAAm aquous solution is cloudy (phase separation occurred). In contrast, when the temperature is lower than the LCST, PNIPAAm is soluble in water (a homogeneous solution). The lower critical solution temperature (LCST) in aqueous solution of PNIPAAm was about 32~33°C. We prepared nano-scaled PNIPAAm particles containing carboxylic group on their surfaces by introducing acrylic acid monomer. The carboxylic groups were applied to conjugate with the amino group of the CD34 antibody. This immuno-conjugate can be applied on targeting the human CD34 positive cells, peripheral blood progenitor cells included, for cell purification and drug controlled release. In order to the active responding of controlled release of the conjugate in the body influenced by temperature, we hope to estimate the shifting of the gel-collapse temperature or cloud point of the immuno-conjugates by dynamic light scattering (DLS) and UV absorption. The results show that the gel-collapse temperature of the nano-particle was not significantly affected by the content of AA between 1.5~5 mol%. However, cloud point of the solution was elevated by the conjugation of CD34 antibody to 37°C. When CD34-conjugated particle was subsequently incorporated with recombinant FLT3-ligand, which is a smaller molecule compare to CD34 antibody, cloud point of the solution was not affected.

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Constrained thermoresponsive polymers – new insights into fundamentals and applications

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.17.138 ◽

2021 ◽

Vol 17 ◽

pp. 2123-2163

Author(s):

Patricia Flemming ◽

Alexander S Münch ◽

Andreas Fery ◽

Petra Uhlmann

Keyword(s):

Phase Transition ◽

Current Knowledge ◽

Polymer Chains ◽

Switching Behavior ◽

Solution Temperature ◽

Miscibility Gap ◽

Underlying Structure ◽

Thermoresponsive Polymers ◽

Critical Solution Temperature ◽

Stimuli Responsive Polymers

In the last decades, numerous stimuli-responsive polymers have been developed and investigated regarding their switching properties. In particular, thermoresponsive polymers, which form a miscibility gap with the ambient solvent with a lower or upper critical demixing point depending on the temperature, have been intensively studied in solution. For the application of such polymers in novel sensors, drug delivery systems or as multifunctional coatings, they typically have to be transferred into specific arrangements, such as micelles, polymer films or grafted nanoparticles. However, it turns out that the thermodynamic concept for the phase transition of free polymer chains fails, when thermoresponsive polymers are assembled into such sterically confined architectures. Whereas many published studies focus on synthetic aspects as well as individual applications of thermoresponsive polymers, the underlying structure–property relationships governing the thermoresponse of sterically constrained assemblies, are still poorly understood. Furthermore, the clear majority of publications deals with polymers that exhibit a lower critical solution temperature (LCST) behavior, with PNIPAAM as their main representative. In contrast, for polymer arrangements with an upper critical solution temperature (UCST), there is only limited knowledge about preparation, application and precise physical understanding of the phase transition. This review article provides an overview about the current knowledge of thermoresponsive polymers with limited mobility focusing on UCST behavior and the possibilities for influencing their thermoresponsive switching characteristics. It comprises star polymers, micelles as well as polymer chains grafted to flat substrates and particulate inorganic surfaces. The elaboration of the physicochemical interplay between the architecture of the polymer assembly and the resulting thermoresponsive switching behavior will be in the foreground of this consideration.

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Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.9.315 ◽

2013 ◽

Vol 9 ◽

pp. 2803-2811 ◽

Cited By ~ 9

Author(s):

Julian Fischer ◽

Helmut Ritter

Keyword(s):

Differential Scanning Calorimetry ◽

Lower Critical Solution Temperature ◽

Setting Time ◽

Diglycidyl Ether ◽

Solution Temperature ◽

Scanning Calorimetry ◽

Critical Solution Temperature ◽

Lcst Behavior ◽

Oscillatory Rheology ◽

Amine Adducts

2-Amino-N-isopropylacetamide and α-amino-ε-caprolactam were reacted with glycerol diglycidyl ether to give novel oligomeric thermoresponsive epoxide–amine adducts. These oligomers exhibit a lower critical solution temperature (LCST) behavior in water. The solubility properties were influenced with randomly methylated β-cyclodextrin (RAMEB-CD) and the curing properties of the amine–epoxide mixtures were analyzed by oscillatory rheology and differential scanning calorimetry, whereby significant differences in setting time, viscosity, and stiffness were observed.

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Novel Polymerization of Myrcene in Aqueous Media via Cyclodextrin-Complexes

e-Polymers ◽

10.1515/epoly.2007.7.1.527 ◽

2007 ◽

Vol 7 (1) ◽

Cited By ~ 8

Author(s):

SooWhan Choi ◽

Helmut Ritter

Keyword(s):

Room Temperature ◽

Aqueous Media ◽

Gel Permeation Chromatography ◽

Solution Temperature ◽

Cyclodextrin Complexes ◽

Scanning Calorimetry ◽

Critical Solution Temperature ◽

Gel Permeation ◽

Redox Initiator ◽

C Nmr

AbstractFree radical homopolymerization with methylated β-cyclodextrin (CD) complexed myrcene (1a) and co-polymerization of 1a with diethyl fumarate (2a) and styrene (3a) were carried out using redox initiator in aqueous media at room temperature. Control experiments showed that uncomplexed myrcene (1) does not polymerize under similar conditions in water. The polymers obtained were characterized by means of 1H/13C-NMR spectroscopy, differential scanning calorimetry (DSC) and gel-permeation chromatography (GPC). Additionally, Nisopropylacrylamide containing copolymer was synthesized in water using redox initiator and the lower critical solution temperature (LCST) behaviour was studied.

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Superabsorbent Nanohydrogels of Poly (N-Isopropyl Acrylamide-Co-Itaconic Acid) Grafted on Starch — Synthesis and Swelling Study

Nano LIFE ◽

10.1142/s1793984416500057 ◽

2016 ◽

Vol 06 (02) ◽

pp. 1650005 ◽

Cited By ~ 2

Author(s):

Karim Pourjamal ◽

Marziyeh Fathi ◽

Ali Akbar Entezami ◽

Mohammad Hasanzadeh ◽

Nasrin Shadjou

Keyword(s):

Itaconic Acid ◽

Starch Synthesis ◽

Ammonium Persulfate ◽

Solution Temperature ◽

Scanning Calorimetry ◽

Critical Solution Temperature ◽

Dsc Studies ◽

Isopropyl Acrylamide ◽

Effects Of Ph

Biopolymer-based superabsorbent nanohydrogel consisting of N-isopropylacrylamide and itaconic acid (IA) was grafted on to starch backbone in an aqueous solution in the absence of the cross-linker agents. The copolymerization reaction occurred in the presence of ammonium persulfate (APS) as an initiator. The effect of N-isopropylacrylamide-to-IA ratio and different concentrations of initiator were investigated. The nanohydrogel composition was characterized by Fourier transform infrared spectroscopy (FTIR). The thermal stability was analyzed by Thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) studies were employed for determination of lower critical solution temperature in hydrogels. Dynamic light scattering analysis showed a narrow size distribution around 70–200[Formula: see text]nm for the synthesized nanohydrogels. The effects of pH on swelling behavior of the hydrogel were investigated. The obtained nanohydrogels, due to their pH and thermo dual sensitive properties, have the potential to be used in the drug delivery systems.

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Thermodynamic Interactions in Blends of Polydienes

Rubber Chemistry and Technology ◽

10.5254/1.3538820 ◽

1999 ◽

Vol 72 (4) ◽

pp. 580-586 ◽

Cited By ~ 4

Author(s):

Ramanan Krishnamoorti

Keyword(s):

Small Angle Neutron Scattering ◽

Room Temperature ◽

Single Phase ◽

Solution Temperature ◽

Scanning Calorimetry ◽

Binary Blends ◽

Critical Solution Temperature ◽

Dsc Measurements ◽

Lcst Behavior ◽

Mixed Microstructure

Abstract Thermodynamic interactions and phase behavior in binary blends of model mixed microstructure polybutadienes with model 1,4-polyisoprene were studied using small angle neutron scattering and differential scanning calorimetry (DSC). The microstructure of the polybutadiene ranged from 8% 1,2 (92% 1,4) to 90% 1,2 (10% 1,4) units, while the polyisoprene contained 93% 1,4 and 7% 3,4 units. The blends of protonated polybutadienes (HPB) with deuterated 1,4 polyisoprene (DPI) exhibited lower critical solution temperature (LCST) behavior when the polybutadiene contained 38 mol % or more of 1,2 units. Below this 1,2 content of the polybutadiene, all HPB/DPI blends were found to be phase separated at all temperatures above 25 °C. The DSC measurements revealed that other than a blend containing 8% 1,2-polybutadiene and (protonated) 1,4 polyisoprene, all other blends were single phase at room temperature. These results are understood in the context of previous work performed by Han and coworkers on deuterated polybutadiene-protonated polyisoprene blends.

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SOLUBILITY AND MISCIBILITY OF REFRIGERANTS R407C AND R410A WITH SYNTHETIC COMPRESSOR OILS

Refrigeration Engineering and Technology ◽

10.15673/ret.v52i3.121 ◽

2016 ◽

Vol 52 (3) ◽

Author(s):

V. Z. Geller ◽

N. I. Lapardin

Keyword(s):

Low Temperature ◽

Visual Observation ◽

Solution Temperature ◽

Miscibility Gap ◽

Critical Solution Temperature ◽

Temperature Range ◽

Lower Viscosity ◽

Mass Fractions ◽

Viscosity Grade ◽

Simple Equations

In this paper, solubility and low temperature miscibility of refrigerants R407C and R410A in four different commercial Polyolester (POE) lubricants, produced by the same company but with different ISO standard viscosity grade, are measured with the aim to evaluate the possible correlation of solubility and miscibility with standard viscosity of the lubricant. Vapor pressure (solubility) is measured using calibrated, constant volume cells at oil mass fractions 30, 50, 70, 80, and 90% over a temperature range from -20 to 100 °C, and pressures up to 5 MPa. The measurements of low temperature miscibility limit (lower critical solution temperature LCST) were made using high-pressure sapphire cell. LCST was directly obtained by visual observation of a «milky haze» followed by a phase separation. Miscibility data were obtained at oil mass fractions from 5 to 50% over a temperature range from -60 to 0 °C. A set of simple equations was derived to describe the experimental results. Analysis of the obtained results showed that the solubility of refrigerant/lubricant mixtures depends weakly on the viscosity grade of the oil. At the same time, the miscibility gap (LCST) differ much bigger for various refrigerant/lubricant mixtures. The lower viscosity grade of the oil, the lower LCST of the refrigerant/lubricant mixture. LCSTs for the mixtures of R407C with the lubricants with the viscosity grades 32 and 220 differ by 30-45 °С.

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Identification of Phase Fraction–Temperature Curves from Heat Capacity Data for Numerical Modeling of Heat Transfer in Commercial Paraffin Waxes

Energies ◽

10.3390/en13195149 ◽

2020 ◽

Vol 13 (19) ◽

pp. 5149 ◽

Cited By ~ 2

Author(s):

Tilman Barz ◽

Johannes Krämer ◽

Johann Emhofer

Keyword(s):

Heat Transfer ◽

Heat Capacity ◽

Numerical Solutions ◽

Spline Approximation ◽

Heat Capacity Data ◽

Phase Fraction ◽

Supplementary Information ◽

Scanning Calorimetry ◽

Apparent Heat Capacity ◽

Capacity Data

The area-proportional baseline method generates phase fraction–temperature curves from heat capacity data of phase change materials. The curves describe the continuous conversion from solid to liquid over an extended temperature range. They are consistent with the apparent heat capacity and enthalpy modeling approach for the numerical solution of heat transfer problems. However, the curves are non-smooth, discrete signals. They are affected by noise in the heat capacity data and should not be used as input to continuous simulation models. This contribution proposes an alternative method based on spline approximation for the generation of consistent and smooth phase fraction–temperature, apparent heat capacity–temperature and enthalpy–temperature curves. Applications are presented for two commercial paraffins from Rubitherm GmbH considering heat capacity data from Differential Scanning Calorimetry and 3-layer-calorimetry. Apparent heat capacity models are validated for melting experiments using a compact heat exchanger. The best fitting models and the most efficient numerical solutions are obtained for heat capacity data from 3-layer-calorimetry using the proposed spline approximation method. Because of these promising results, the method is applied to melting data of all 44 Rubitherm paraffins. The computer code of the corresponding phase transition models is provided in the Supplementary Information.

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