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.

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.

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.

High-temperature carbon plastics based on thermoreactive polyimide binder

2020 ◽  
pp. 89-102
Author(s):  
M. I. Valueva ◽  
I. V. Zelenina ◽  
M. A. Zharinov ◽  
M. A. Khaskov
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Strength Properties ◽  
High Glass Transition Temperature ◽  
Reinforced Plastics ◽  
Carbon Plastics ◽  
Fundamental Possibility ◽  
Fiber Reinforced Plastics

The article presents results of studies of experimental carbon plastics based on thermosetting PMRpolyimide binder. Сarbon fiber reinforced plastics (CFRPs) are made from prepregs prepared by melt and mortar technologies, so the rheological properties of the polyimide binder were investigated. The heat resistance of carbon plastics was researched and its elastic-strength characteristics were determined at temperatures up to 320°С. The fundamental possibility of manufacturing carbon fiber from prepregs based on polyimide binder, obtained both by melt and mortar technologies, is shown. CFRPs made from two types of prepregs have a high glass transition temperature: 364°C (melt) and 367°C (solution), with this temperature remaining at the 97% level after boiling, and also at approximately the same (86–97%) level of conservation of elastic strength properties at temperature 300°С.

scholarly journals Cure Kinetics Modeling of a High Glass Transition Temperature Epoxy Molding Compound (EMC) Based on Inline Dielectric Analysis

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1734
Author(s):  
Erick Franieck ◽  
Martin Fleischmann ◽  
Ole Hölck ◽  
Larysa Kutuzova ◽  
Andreas Kandelbauer
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Kinetic Parameters ◽  
Measurement Techniques ◽  
Process Conditions ◽  
Dielectric Analysis ◽  
High Glass Transition Temperature ◽  
General Process ◽  
Molding Compound

We report on the cure characterization, based on inline monitoring of the dielectric parameters, of a commercially available epoxy phenol resin molding compound with a high glass transition temperature (>195 °C), which is suitable for the direct packaging of electronic components. The resin was cured under isothermal temperatures close to general process conditions (165–185 °C). The material conversion was determined by measuring the ion viscosity. The change of the ion viscosity as a function of time and temperature was used to characterize the cross-linking behavior, following two separate approaches (model based and isoconversional). The determined kinetic parameters are in good agreement with those reported in the literature for EMCs and lead to accurate cure predictions under process-near conditions. Furthermore, the kinetic models based on dielectric analysis (DEA) were compared with standard offline differential scanning calorimetry (DSC) models, which were based on dynamic measurements. Many of the determined kinetic parameters had similar values for the different approaches. Major deviations were found for the parameters linked to the end of the reaction where vitrification phenomena occur under process-related conditions. The glass transition temperature of the inline molded parts was determined via thermomechanical analysis (TMA) to confirm the vitrification effect. The similarities and differences between the resulting kinetics models of the two different measurement techniques are presented and it is shown how dielectric analysis can be of high relevance for the characterization of the curing reaction under conditions close to series production.

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