Thermodynamic Interactions in Blends of Polydienes

1999 ◽  
Vol 72 (4) ◽  
pp. 580-586 ◽  
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.

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

2013 ◽  
Vol 9 ◽  
pp. 2803-2811 ◽  
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.

Novel Polymerization of Myrcene in Aqueous Media via Cyclodextrin-Complexes

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
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.

Investigations on the polymorphism and pseudopolymorphism of clobetasone butyrate

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.

scholarly journals Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels

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.

Chemically disordered Ni3Al synthesized by high vacuum evaporation

1991 ◽  
Vol 6 (10) ◽  
pp. 2019-2021 ◽  
Author(s):  
S.R. Harris ◽  
D.H. Pearson ◽  
C.M. Garland ◽  
B. Fultz
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Single Phase ◽  
High Vacuum ◽  
Liquid Nitrogen Temperature ◽  
Vacuum Evaporation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size

Films of chemically disordered fcc Ni3Al were synthesized by the vacuum evaporation of Ni3Al onto room temperature and liquid nitrogen temperature substrates. X-ray diffractometry and transmission electron microscopy showed the material to be single phase with an average grain size of about 4 nm. The formation of the equilibrium L12 ordered phase occurred simultaneously with grain growth at temperatures above 350°C. Differential scanning calorimetry provided ordering enthalpies of 7 kJ/mole and 9 kJ/mole for material evaporated onto room temperature and liquid nitrogen temperature substrates, respectively.

scholarly journals Combinatorial discovery of small-molecule 1,2,3-triazolium ionic liquids exhibiting lower critical solution temperature phase transition

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yen-Ho Chu ◽  
Mou-Fu Cheng ◽  
Yung-Hsin Chiang
Keyword(s):  
Phase Transition ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Phase Transitions ◽  
Small Molecule ◽  
Room Temperature ◽  
Solution Temperature ◽  
Temperature Phase ◽  
Critical Solution Temperature ◽  
True Value

Abstract Both lower and upper critical solution temperature (LCST and UCST) systems are two typical phase behaviors of thermoresponsive materials with solvents, in which LCST is far less common than UCST. Recent studies on ionic liquids carrying LCST phase transitions have predominantly focused on quaternary ammonium- and phosphonium-based ionic salts. Based on the 1,2,3-triazole core structure assemblable by azide-alkyne cycloaddition click reaction, this work reports the combinatorial synthesis of 1,3,4-trialkylated 1,2,3-triazolium ionic liquids in three libraries with a total of 160 ionic liquids and demonstrates, for the first time, their values in temperature-switchable phase transition with water. In this work, the successful discovery of a new thermoresponsive ionic liquid b26, based on the structure-and-phase separation study of b8 and b9, perfectly exemplified the true value of the tunability of ionic liquid fine structures. For all 160 ionic liquids synthesized, 155 are liquid at room temperature and 22 room-temperature ionic liquids were found to exhibit thermoresponsive phase transitions having low Tc values in water. To the best of our knowledge, this comprehensive study is the first report of small-molecule 1,2,3-triazolium ionic liquids that exhibit LCST property in water.

Preparation and Characterization of Elastomers Based on Polydimethylsiloxane/Poly(methyl methacrylate) Blends

2012 ◽  
Vol 535-537 ◽  
pp. 1193-1196
Author(s):  
Nai Qiang Zhang ◽  
Jian Dong ◽  
Hong Yu Chen
Keyword(s):  
Methyl Methacrylate ◽  
Room Temperature ◽  
Radical Copolymerization ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
Silicone Elastomers ◽  
Poly Methyl Methacrylate ◽  
Dsc Measurements ◽  
Pmma Blends

Polydimethylsiloxane/poly (methyl methacrylate) (PDMS/PMMA) blends were prepared by radical copolymerization of methyl methacrylate (MMA) and divinylbenzene (DVB) in the presence of PDMS. Elastomers based on PDMS/PMMA blends were formed by cross-linking PDMS with methyltriethoxysilane (MTES). Mechanical property measurements show that the elastomers thus formed exhibit superior tensile strength with respect to general room temperature vulcanized silicone elastomers containing silica. Moreover, investigations were carried out on the elastomers by extraction, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements. SEM shows that the elastomer has a microphase-separated structure consisting of dispersed PMMA domains within a continuous PDMS matrix. DSC result shows that the elastomers display two glass transition temperatures and confirm the incompatible nature of PDMS and PMMA.

scholarly journals Lithium tetrachloridoaluminate, LiAlCl4: a new polymorph (oP12,Pmn21) with Li+in tetrahedral interstices

2017 ◽  
Vol 73 (10) ◽  
pp. 1426-1429 ◽  
Author(s):  
Stephan W. Prömper ◽  
Walter Frank
Keyword(s):  
Room Temperature ◽  
Aluminium Chloride ◽  
Lithium Cation ◽  
Scanning Calorimetry ◽  
Lithium Ions ◽  
Monoclinic Modification ◽  
Cation Site ◽  
Monoclinic Form ◽  
Dsc Measurements ◽  
Orthorhombic Modification

Dissolving lithium chloride and aluminium chloride in boilingpara- ormeta-xylene and keeping the colourless solution at room temperature led to crystal growth of a new modification of lithium tetrachloridoaluminate, LiAlCl4, which represents a second modification (oP12,Pmn21) of the ternary salt besides the long known monoclinic form [LiAlCl4(mP24,P21/c); Mairesseet al.(1977).Cryst. Struct. Commun.6, 15–18]. The crystal structures of both modifications can be described as slightly distorted hexagonal closest packings of chloride anions. While the lithium cations in LiAlCl4(mP24) are in octahedral coordination and the aluminium and lithium ions in the solid of orthorhombic LiAlCl4occupy tetrahedral interstices with site symmetriesmand 1, respectively, the lithium cation site being half-occupied (defect wurtz-stannite-type structure). From differential scanning calorimetry (DSC) measurements, no evidence for a phase transition of the orthorhombic modification is found until the material melts at 148 °C (Tpeak= 152 °C). The melting point is nearly identical to the literature data for LiAlCl4(mP24) [146 °C; Weppner & Huggins (1976).J. Electrochem. Soc.124, 35–38]. From the melts of both polymorphs, the monoclinic modification recrystallizes.

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