Investigation of the LCST-Thermoresponsive Behavior of Novel Oligo(Ethylene Glycol)-Modified Pentafluorostyrene Homopolymers

Amphiphilic tetrafluorostyrene monomers (EFS8) carrying in the para position an oligoethylene glycol chain containing 8 oxyethylenic units on average were synthesized and used for preparation via activator regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP) of the corresponding amphiphilic homopolymers (pEFS8-x) with different degrees of polymerization (x = 26 and 46). Combining light transmittance and nano-differential scanning calorimetry (n-DSC) measurements revealed that pEFS8-x homopolymers displayed a lower critical solution temperature (LCST) thermoresponsive behavior in water solutions. Moreover, n-DSC measurements revealed the presence in heating scans of a broad endothermic peak ascribable to the dehydration process of the polymer single chains (unimers) and their collapse into aggregates. Consistently, dynamic light scattering (DLS) measurements showed below the LCST the presence of small nanostructures with a hydrodynamic diameter size Dh of 6–7 nm, which collapsed into concentration-dependent larger multichain aggregates (Dh = 300–3000 nm) above LCST. Interestingly, n-DSC data showed that the unimer-aggregate transition was reversible up to a specific temperature (Trev) of each homopolymer, which in any case was higher than Tmax. When heating above Trev the transition was no longer reversible, causing the shift of Tonset and Tmax at lower values, thus suggesting an increase in hydrophobicity of the polymer systems associated with a temperature-dependent dehydration process.

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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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Structure and Properties of Silk Grafted with N, N-Dimethylaminoethyl Methacrylate via the ARGET ATRP Method

Journal of Engineered Fibers and Fabrics ◽

10.1177/155892501200702s01 ◽

2012 ◽

Vol 7 (2_suppl) ◽

pp. 155892501200702

Author(s):

Tieling Xing ◽

Shiwei Li ◽

Xia Xu ◽

Guoqiang Chen

Keyword(s):

Photoelectron Spectroscopy ◽

Gas Permeability ◽

Antibacterial Properties ◽

Structure And Properties ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Dimethylaminoethyl Methacrylate ◽

Dsc Measurements ◽

Arget Atrp

Silk with antibacterial properties was grafted using dimethylaminoethyl methacrylate (DMAEMA) in water by the ATRP method. The structure and properties of silk-grafted-PDMAEMA (Silk-g-PDMAEMA) and quaternized grafted silk (Q-Silk-g-PDMAEMA) were investigated. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the grafting of DMAEMA and the quarternization. Differential scanning calorimetry (DSC) measurements indicate that the thermal stability of Silk-g-PDMAEMA slightly increased compared with the control silk. X-ray diffraction (XRD) curves demonstrate that the crystalline structure of Silk-g-PDMAEMA remained unchanged regardless of the DMAEMA grafting. The Q-Silk-g-PDMAEMA had good antibacterial properties when exposed to both Staphylococcus aureu and Escherichia coli, and had good washing fastness. The breaking strength, whiteness and gas permeability of Silk-g-PDMAEMA slightly decreased, which had no effect on the intrinsic properties of silk fabric.

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Using Reverse Osmosis Membrane at High Temperature for Water Recovery and Regeneration from Thermo-Responsive Ionic Liquid-Based Draw Solution for Efficient Forward Osmosis

Membranes ◽

10.3390/membranes11080588 ◽

2021 ◽

Vol 11 (8) ◽

pp. 588

Author(s):

Eiji Kamio ◽

Hiroki Kurisu ◽

Tomoki Takahashi ◽

Atsushi Matsuoka ◽

Tomohisa Yoshioka ◽

...

Keyword(s):

Ionic Liquid ◽

High Temperature ◽

Energy Saving ◽

Osmotic Pressure ◽

Reverse Osmosis ◽

Forward Osmosis ◽

Solution Temperature ◽

Water Recovery ◽

Temperature Dependent ◽

Draw Solution

Forward osmosis (FO) membrane process is expected to realize energy-saving seawater desalination. To this end, energy-saving water recovery from a draw solution (DS) and effective DS regeneration are essential. Recently, thermo-responsive DSs have been developed to realize energy-saving water recovery and DS regeneration. We previously reported that high-temperature reverse osmosis (RO) treatment was effective in recovering water from a thermo-responsive ionic liquid (IL)-based DS. In this study, to confirm the advantages of the high-temperature RO operation, thermo-sensitive IL-based DS was treated by an RO membrane at temperatures higher than the lower critical solution temperature (LCST) of the DS. Tetrabutylammonium 2,4,6-trimethylbenznenesulfonate ([N4444][TMBS]) with an LCST of 58 °C was used as the DS. The high-temperature RO treatment was conducted at 60 °C above the LCST using the [N4444][TMBS]-based DS-lean phase after phase separation. Because the [N4444][TMBS]-based DS has a significantly temperature-dependent osmotic pressure, the DS-lean phase can be concentrated to an osmotic pressure higher than that of seawater at room temperature (20 °C). In addition, water can be effectively recovered from the DS-lean phase until the DS concentration increased to 40 wt%, and the final DS concentration reached 70 wt%. From the results, the advantages of RO treatment of the thermo-responsive DS at temperatures higher than the LCST were confirmed.

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Thermodynamics and Intermolecular Interactions of Nicotinamide in Neat and Binary Solutions: Experimental Measurements and COSMO-RS Concentration Dependent Reactions Investigations

International Journal of Molecular Sciences ◽

10.3390/ijms22147365 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7365

Author(s):

Piotr Cysewski ◽

Maciej Przybyłek ◽

Anna Kowalska ◽

Natalia Tymorek

Keyword(s):

Intermolecular Interactions ◽

Vibrational Energy ◽

Perfect Match ◽

Zero Point ◽

Heat Capacity Change ◽

Free Energies ◽

Temperature Dependent ◽

Scanning Calorimetry ◽

Capacity Change ◽

Self Association

In this study, the temperature-dependent solubility of nicotinamide (niacin) was measured in six neat solvents and five aqueous-organic binary mixtures (methanol, 1,4-dioxane, acetonitrile, DMSO and DMF). It was discovered that the selected set of organic solvents offer all sorts of solvent effects, including co-solvent, synergistic, and anti-solvent features, enabling flexible tuning of niacin solubility. In addition, differential scanning calorimetry was used to characterize the fusion thermodynamics of nicotinamide. In particular, the heat capacity change upon melting was measured. The experimental data were interpreted by means of COSMO-RS-DARE (conductor-like screening model for realistic solvation–dimerization, aggregation, and reaction extension) for concentration dependent reactions. The solute–solute and solute–solvent intermolecular interactions were found to be significant in all of the studied systems, which was proven by the computed mutual affinity of the components at the saturated conditions. The values of the Gibbs free energies of pair formation were derived at an advanced level of theory (MP2), including corrections for electron correlation and zero point vibrational energy (ZPE). In all of the studied systems the self-association of nicotinamide was found to be a predominant intermolecular complex, irrespective of the temperature and composition of the binary system. The application of the COSMO-RS-DARE approach led to a perfect match between the computed and measured solubility data, by optimizing the parameter of intermolecular interactions.

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Polypropylene/Lignin/POSS Nanocomposites: Thermal and Wettability Properties, Application in Water Remediation

Materials ◽

10.3390/ma14143950 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3950

Author(s):

Abeer Alassod ◽

Syed Rashedul Islam ◽

Mina Shahriari Khalaji ◽

Rogers Tusiime ◽

Wanzhen Huang ◽

...

Keyword(s):

Organic Liquid ◽

Contact Angles ◽

Water Remediation ◽

Scanning Calorimetry ◽

Water Contact ◽

Thermally Induced ◽

Dsc Measurements ◽

Infrared Measurement ◽

Oligomeric Silsesquioxane ◽

Tga And Dsc

Compositing is an interesting strategy that has always been employed to introduce or enhance desired functionalities in material systems. In this paper, sponges containing polypropylene, lignin, and octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) were successfully prepared via an easy and elegant strategy called thermally induced phase separation (TIPS). To fully explore the behaviour of different components of prepared sponges, properties were characterized by a thermogravimetric analyser (TGA), differential scanning calorimetry (DSC), Fourier transform infrared measurement (FTIR), and scanning electron microscopy (SEM). Furthermore, wettability properties toward an organic liquid and oil were investigated. The FTIR analysis confirmed the chemical modification of the components. TGA and DSC measurements revealed thermal stability was much better with an increase in OV-POSS content. OV-POSS modified sponges exhibited ultra-hydrophobicity and high oleophilicity with water contact angles of more than 125°. The SEM revealed that POSS molecules acted as a support for reduced surface roughness. Moreover, OV-POSS-based blend sponges showed higher sorption capacities compared with other blend sponges without OV-POSS. The new blend sponges demonstrated a potential for use as sorbent engineering materials in water remediation.

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Investigations on the polymorphism and pseudopolymorphism of clobetasone butyrate

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc2011027 ◽

2011 ◽

Vol 76 (5) ◽

pp. 553-566

Author(s):

Christian Näther ◽

Inke Jeß

Keyword(s):

Room Temperature ◽

Polymorphic Form ◽

Stable Form ◽

Scanning Calorimetry ◽

Amorphous Form ◽

Space Group ◽

Dsc Measurements ◽

Independent Molecules ◽

Solvent Molecules ◽

Similar Conformation

Clobetasone butyrate was investigated for polymorphism and pseudopolymorphism. Solvent mediated conversion experiments reveal that the commercially available form I represent the thermodynamically most stable form at room temperature and DSC measurements shows that it should also be the most stable form until melting. Form I crystallizes in space groupP212121with three crystallographically independent molecules of similar conformation. From methanol an additional pseudo polymorphic form was discovered. In the crystal structure (space groupP212121) the solvent molecules are connected to the clobetasone butyrate molecules by O–H···O hydrogen bonding. Investigations of the solvate using thermogravimetry, differential thermoanalysis as well as differential scanning calorimetry proves, that on solvent removal an amorphous form is obtained that crystallizes into form I on further heating.

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Effects of Aging on the Microstructure and Phase Transformation Behavior of Cu-Al-Mn Shape Memory Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.882.21 ◽

2021 ◽

Vol 882 ◽

pp. 21-27

Author(s):

Seyed Veghar Seyedmohammadi ◽

Amin Radi ◽

Guney Guven Yapici

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Aging Treatment ◽

Scanning Calorimetry ◽

Dsc Measurements ◽

Peak Aged Condition ◽

Peak Aged ◽

Rolled Condition ◽

The One ◽

Effects Of Aging

In the present work, the effects of artificial aging treatment on the transformation temperatures and hardness of Cu-Al-Mn shape memory alloy have been investigated. The aging processes have been performed on the one-time re-melted and 90% rolled samples. Differential scanning calorimetry reveals that reverse transformation is present for the re-melted sample which is aged at 400°C. However, in 90% rolled condition, this transformation takes place at 200°C and 300°C. Hardness examination shows that the aged specimens possess higher values in hardness in comparison to un-aged samples at all studied temperatures. Although, the peak-aged condition was demonstrated at 300°C for the re-melted sample, the rolled sample displayed increased hardness levels up to 500°C. Based on the DSC measurements and microstructural observations, it can be asserted that the thermo-mechanical processing including rolling plus aging at 300°C provides favorable transformation characteristics for shape memory behavior.

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A Facile Synthesis and Characterization of Highly Crystalline Submicro-Sized BiFeO3

Materials ◽

10.3390/ma13133035 ◽

2020 ◽

Vol 13 (13) ◽

pp. 3035

Author(s):

Dovydas Karoblis ◽

Diana Griesiute ◽

Kestutis Mazeika ◽

Dalis Baltrunas ◽

Dmitry V. Karpinsky ◽

...

Keyword(s):

Bismuth Ferrite ◽

Cost Effective ◽

Xrd Analysis ◽

Synthetic Approach ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Dsc Measurements ◽

Optimal Annealing Temperature ◽

Synthesized Materials

In this study, a highly crystalline bismuth ferrite (BFO) powder was synthesized using a novel, very simple, and cost-effective synthetic approach. It was demonstrated that the optimal annealing temperature for the preparation of highly-pure BFO is 650 °C. At lower or higher temperatures, the formation of neighboring crystal phases was observed. The thermal behavior of BFO precursor gel was investigated by thermogravimetric and differential scanning calorimetry (TG-DSC) measurements. X-ray diffraction (XRD) analysis and Mössbauer spectroscopy were employed for the investigation of structural properties. Scanning electron microscopy (SEM) was used to evaluate morphological features of the synthesized materials. The obtained powders were also characterized by magnetization measurements, which showed antiferromagnetic behavior of BFO powders.

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Morphological basis for the complex melting behaviour of isotactic polystyrene

e-Polymers ◽

10.1515/epoly.2002.2.1.544 ◽

2002 ◽

Vol 2 (1) ◽

Author(s):

Mahmoud Al-Hussein ◽

Gert Strobl

Keyword(s):

Morphological Changes ◽

Melting Behaviour ◽

Temperature Dependent ◽

Molten Material ◽

Scanning Calorimetry ◽

Isotactic Polystyrene ◽

X Ray ◽

Long Period ◽

X Ray Scattering ◽

Increasing Temperature

AbstractTemperature-dependent small-angle X-ray scattering spectroscopy of isothermally cold crystallized isotactic polystyrene revealed considerable morphological reorganization during subsequent heating to the melt. Both the crystalline thickness and the long period increased continuously with increasing temperature before the samples finally melted. The temperature dependence of these changes correlated very well with the melting behaviour observed with differential scanning calorimetry. As the temperature increased during a heating scan, the initial lamellae that formed during isothermal crystallization showed only little reorganization until they started to melt. Then, the molten material recrystallized continuously into increasingly thicker lamellae at increasing temperature until they finally melted. As the crystallization temperature approached the final melting temperature of the recrystallized lamellae, the initial lamellae melted without further recrystallization and no morphological changes were seen in this case.

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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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