Characterising glass transition temperatures and glass dynamics in mesoporous silica-based amorphous drugs

2019 ◽  
Vol 21 (35) ◽  
pp. 19686-19694 ◽  
Author(s):  
Eric Ofosu Kissi ◽  
Michael T. Ruggiero ◽  
Nele-Johanna Hempel ◽  
Zihui Song ◽  
Holger Grohganz ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mesoporous Silica ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Drug Molecules ◽  
Glass Dynamics ◽  
Amorphous Drugs ◽  
Amorphous Drug

Amorphous drug molecules bound to MPS surface are restricted in mobility, but they exhibit a primary glass transition temperature.

Properties and Structure of Elastomers

1966 ◽  
Vol 39 (4) ◽  
pp. 881-896 ◽  
Author(s):  
Joginder Lal ◽  
Kenneth W. Scott
Keyword(s):  
Tensile Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Alkyl Group ◽  
Side Chain ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Dynamic Mechanical ◽  
Alkyl Ethers

Abstract The glass transition temperatures of high molecular weight poly (vinyl n-alkyl ethers) decrease with increasing length of the n-alkyl group. On lengthening the n-alkyl group, 14 per cent of the specific volume increase is free volume. Branching or substitution in the alkyl group of the polymer increases the Tg value. A comparison of poly (vinyl n-alkyl ethers) and polymers of normal α-olefins shows that an ether group and a methylene group in the side chain are equivalent in influencing the glass transition temperature. We have varied systematically the side chain alkyl group in poly (vinyl alkyl ethers) and evaluated at 3 different temperatures the influence of these variations on the dynamic properties of the vulcanizates of these polymers. The relative position of the curves, relating dynamic resilience to dynamic modulus of these polymers, is generally in the order of their glass transition temperatures. The dynamic mechanical property data on poly (vinyl n-pentyl ether) and poly (vinyl 2-ethylhexyl ether), which have the same glass transition temperature, fall on a common curve characteristic of the temperature of measurement. Apparently, the Tg is a major factor in correlating the dynamic mechanical behavior of these elastomers. The size and shape of the alkyl group appear to be reflected primarily in their effect on the Tg. Polysulfidic crosslinks are not essential for the attainment of high tensile strength in natural rubber vulcanizates cured with a sulfur-diphenylguanidine system. Data for the samples which had lost significant amounts of polysulfidic crosslinks by reaction with triphenylphosphine fitted a curve of tensile strength as a function of 300 per cent modulus for the control samples.

Well-defined high refractive index poly(monothiocarbonate) with tunable Abbe's numbers and glass-transition temperatures via terpolymerization

2015 ◽  
Vol 6 (27) ◽  
pp. 4978-4983 ◽  
Author(s):  
Ming Luo ◽  
Xing-Hong Zhang ◽  
Bin-Yang Du ◽  
Qi Wang ◽  
Zhi-Qiang Fan
Keyword(s):  
Refractive Index ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Propylene Oxide ◽  
High Refractive Index ◽  
Transition Temperatures ◽  
Cyclohexene Oxide ◽  
Glass Transition Temperatures

Poly(monothiocarbonate) with tunable Abbe's number and glass-transition temperature is synthesized via terpolymerization of COS with propylene oxide and cyclohexene oxide.

scholarly journals High Glass Transition Temperature Fluoropolymers for Hydrophobic Surface Coatings via RAFT Copolymerization

2016 ◽  
Vol 69 (7) ◽  
pp. 725 ◽  
Author(s):  
Molly Rowe ◽  
Guo Hui Teo ◽  
James Horne ◽  
Omar Al-Khayat ◽  
Chiara Neto ◽  
...  
Keyword(s):  
Thin Films ◽  
Contact Angle ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Surface Coatings ◽  
Transition Temperatures ◽  
High Glass Transition Temperature ◽  
Glass Transition Temperatures ◽  
Hydrophobic Polymers

The preparation of polymer thin films or surface coatings that display a static water contact angle >95° often requires hierarchical roughness features or surface functionalization steps. In addition, inherently hydrophobic polymers such as fluoropolymers often possess low glass transition temperatures, reducing their application where thermal stability is required. Herein, the first reported synthesis of 2,3,4,5,6-pentafluorostyrene (PFS) and N-phenylmaleimide (NMI) via reversible addition–fragmentation chain-transfer (RAFT)-mediated free radical polymerization is presented, with a view towards the preparation of inherently hydrophobic polymers with a high glass transition temperature. A suite of copolymers were prepared and characterized, and owing to the inherent rigidity of the maleimide group in the polymer backbone and π–π interactions between adjacent PFS and NMI groups, very high glass transition temperatures were achieved (up to 180°C). The copolymerization of N-pentafluorophenylmaleimide was also performed, also resulting in extremely high glass transition temperature copolymers; however, these polymers did not exhibit characteristics of being under RAFT control. Thin films of PFS-NMI copolymers exhibited a static contact angle ~100°, essentially independent of the amount of NMI incorporated into the polymer.

scholarly journals Azobenzene molecular glasses with tuned glass transition temperatures: from optimal light-induced motion to self-erasable gratings

2020 ◽  
Vol 8 (18) ◽  
pp. 6203-6213
Author(s):  
Austin Diggins ◽  
Eoin Dawson ◽  
Mahnaz Kamaliardakani ◽  
Christian Pellerin ◽  
Ribal Georges Sabat ◽  
...  
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Surface Relief ◽  
Transition Temperatures ◽  
Molecular Glasses ◽  
Glass Transition Temperatures ◽  
Induced Motion ◽  
Surface Relief Gratings

The rate of photomechanical formation of surface relief gratings (SRG) in thin films of azobenzene materials depends on their glass transition temperature (Tg), with self-erasable gratings being formed with materials with sub-ambient Tg.

scholarly journals Differential Scanning Calorimetry for Determining the Thermodynamic Properties of Selected Honeys

2015 ◽  
Vol 59 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Jolanta Tomaszewska-Gras ◽  
Sławomir Bakier ◽  
Kamila Goderska ◽  
Krzysztof Mansfeld
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermodynamic Properties ◽  
Sugar Content ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Complete Liquefaction

Abstract Thermodynamic properties of selected honeys: glass transition temperature (Tg), the change in specifi c heat capacity (ΔCp), and enthalpy (ΔH) were analysed using differential scanning calorimetry (DSC) in relation to the composition i.e. water and sugar content. Glass transition temperatures (Tg) of various types of honey differed significantly (p<0.05) and ranged from -49.7°C (polyfloral) to -34.8°C (sunflower). There was a strong correlation between the Tg values and the moisture content in honey (r = -0.94). The degree of crystallisation of the honey also influenced the Tg values. It has been shown that the presence or absence of sugar crystals influenced the glass transition temperature. For the decrystallised honeys, the Tg values were 6 to 11°C lower than for the crystallised honeys. The more crystallised a honey was, the greater the temperature difference was between the decrystallised and crystallized honey. In conclusion, to obtain reliable DSC results, it is crucial to measure the glass transition after the complete liquefaction of honey.

Proton transport properties of proton-conducting phosphate glasses at their glass transition temperatures

2019 ◽  
Vol 21 (20) ◽  
pp. 10744-10749 ◽  
Author(s):  
Takahisa Omata ◽  
Takuya Yamaguchi ◽  
Satoshi Tsukuda ◽  
Tomohiro Ishiyama ◽  
Junji Nishii ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Transport Properties ◽  
Proton Transport ◽  
Phosphate Glasses ◽  
Proton Mobility ◽  
Glass Transition Temperatures ◽  
Proton Conducting ◽  
Proton Transport Properties

Proton mobility at the glass transition temperature of 32 proton-conducting phosphate glasses converges between 2 × 10−9 and 2 × 10−7 cm2 V−1 s−1.

Study of the Glass Transition Temperature of (Se100-xBix)90Te10 (x = 0, 0.5, 1, 1.5, 2, 2.5, 3) Alloys

2011 ◽  
Vol 316-317 ◽  
pp. 55-58 ◽  
Author(s):  
Deepshikha Sharma ◽  
Saneel K. Thakur
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Network Model ◽  
Differential Analysis ◽  
X Ray Diffraction ◽  
Glass Transition Temperatures ◽  
X Ray ◽  
Xrd Studies

Alloys of (Se100-xBix)90Te10 (x =0, 0.5, 1, 1.5, 2, 2.5, 3 at.%) were prepared by using a conventional melt-quench technique. The samples under investigation were characterized using X-ray diffraction (XRD) and differential analysis (DTA) at a heating rate of 10K/min. It was found, from the XRD studies, that the alloys were amorphous in nature. The glass transition temperatures of the alloys were found to increase with increasing bismuth content. This increase in the glass transition temperature was explained on the basis of a chemically ordered network model.

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