The role of molecular volume and the shape of the hole transport molecule in the morphology of model charge transport composites

2010 ◽  
Vol 88 (3) ◽  
pp. 247-259 ◽  
Author(s):  
Ferdous Khan ◽  
Shalini Khanna ◽  
Ah-Mee Hor ◽  
P. R. Sundararajan
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Charge Transport ◽  
Small Molecules ◽  
Small Molecule ◽  
Hole Transport ◽  
Random Coil ◽  
Molecular Volume ◽  
Van Der Waals Volume

We present a study of the morphology and molecular interactions in a model charge transport composite with 1,1-bis(di-4-tolylaminophenyl) cyclohexane (TAPC) as the hole transport molecule in bisphenol-A polycarbonate (BPAPC) and cyclohexyl polycarbonate, also known as bisphenol-Z polycarbonate (PCZ). Solution NMR shows that while there is aromatic interaction between the phenyl groups of the polycarbonate and TAPC, the broadening of the peaks corresponding to the latter indicates a decrease in the rotational motion. FTIR spectroscopy also exhibits frequency shifts of the aromatic C–H absorption peaks, which parallels the extent of the depression of the glass transition temperature (Tg) of the polycarbonate. These are compared with the previous results for N,N-diphenyl-N,N-bis(3-methylphenyl)-[1,1-biphenyl]-4,4-diamine (TPD) and tri-p-tolylamine (TTA), and the differences are rationalized on the basis of the molecular shape and van der Waals volume of the small molecules. It is proposed that when the polycarbonate is in a random coil conformation, spherical small molecules (e.g., TAPC and TTA) reduce the glass transition temperature much more than a rodlike small molecule (e.g., TPD). Annealing at a temperature just below the Tg of the polycarbonate was used as a means of simulating accelerated ageing. Upon annealing, phase separation and crystallization of TAPC occurs and leads to a recovery of the Tg of the polymer significantly. The Tg recovery in this case is much more significant than in the case of TPD. The average crystal sizes are about ten times smaller than the crystals obtained in the case of TPD for the same temperature of annealing. To enhance the charge mobility, it might actually be advantageous to induce submicron crystals of the small molecule, while keeping the film transparent.

Effect of Adsorption on Reinforcement of Filled Polyurethane

1977 ◽  
Vol 50 (2) ◽  
pp. 333-341 ◽  
Author(s):  
J. Seto
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Adsorption ◽  
Random Coil ◽  
Chain Formation ◽  
Network Chain ◽  
Effective Network

Abstract The effective network chains, ns formed at the polyurethane-particle interface are brought about by physical adsorption of the polymer from solution. The relation between ns and adsorption, Γs, is given as Equation (3). The coefficient K is evaluated as 10. This value supports multicontact adsorption and agrees with random coil dimensions. The pretreating of powder by a surfactant (oleate) brings about neither adsorption nor network chain formation. The glass transition temperature increases with increasing amount of adsorption.

scholarly journals Diffusion Coefficients and Activation Energies of Diffusion of Organic Molecules in Polystyrene below and above Glass Transition Temperature

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1317
Author(s):  
Frank Welle
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Diffusion Coefficients ◽  
Organic Molecules ◽  
Activation Energies ◽  
Molecular Volume ◽  
Desorption Kinetics ◽  
Exponential Factor ◽  
Diffusion Behavior

General Purpose Polystyrene (GPPS) and High Impact Polystyrene (HIPS) is used in packaging food as well as for technical products. Knowledge of the diffusion behavior of organic molecules in polystyrene (PS) is important for the evaluation of the diffusion and migration process. Within this study, diffusion coefficients were determined in GPPS and HIPS below and above the glass transition temperature. Diffusion coefficients were determined from desorption kinetics into the gas phase using spiked GPPS and HIPS sheets as well as from permeation kinetics through a thin GPPS film. Overall, 187 diffusion coefficients were determined in GPPS and HIPS at temperatures between 0 °C and 115 °C. From the temperature dependency of the diffusion coefficients 45 activation energies of diffusion EA and the pre-exponential factor D0 were determined. As expected, the activation energies of diffusion EA show a strong dependency from the molecular volume of the investigated substances. At the glass transition temperature, only a slight change of the diffusion behavior were observed. Based on EA and D0, prediction parameters for diffusion coefficients were established.

scholarly journals Glass transition temperature and elastic modulusof nanocomposites based on polyimides

Vestnik MGSU ◽  
2015 ◽  
pp. 50-63
Author(s):  
Tat’yana Anatol’evna Matseevich ◽  
Marina Nikolaevna Popova ◽  
Andrey Aleksandrovich Askadskiy
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Elastic Modulus ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Chemical Structure ◽  
Van Der Waals Volume ◽  
Polar Groups ◽  
Wide Range ◽  
Nanoparticles Concentration

Today great attention is paid to production and research of the mechanical and termal properties of nanocomposites based on polyimides. These polymers are heatresisting and possess the increased mechanical properties in wide range of temperatures. Various nanoparticles are introduced into polyimides: graphite nanotubes and flatparticles, the particles of SiO , the surface of which is modified, the particles of ZrOandmontmorillonite, etc.The authors analyzed the influence of nanoparticles on the glass transition temper-ature T and elastic modulus E of the polyimides based on 1,3-bis-(3,3’,4,4’-dicarboxy-phenoxy)benzene and 4,4’-bis-(4-aminophenoxy)biphenyl, and pyromellitic dianhydride and oxydianiline. Nanoparticles introduced in small amounts are produced of graphite and ZrO . The suggested ratios take into account the chemical structure of the polymer and nanoparticles, as well as the structure of their surface in case of chemical modification; the concentration of nanoparticles and their form, the number of polar groups on the surface. The number of polar groups and nanoparticles’ concentration have the greatest influence on T . The elastic modulus of nanocomposites depending on nanoparticles’ concentration is connected with van der Waals volume of the repeating unit of polymer and nanoparticle.

The Dependence of Glass Transition Temperature and Flow Temperature on Solvent or Plasticiser Concentration

2017 ◽  
Vol 44 (1) ◽  
pp. 17-22 ◽  
Author(s):  
T.A. Matseevich ◽  
L.M. Goleneva ◽  
E.S. Afanas'ev ◽  
E.A. Kurskaya ◽  
O.V. Kovriga ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Intermolecular Interaction ◽  
Chemical Structure ◽  
Van Der Waals ◽  
Flow Temperature ◽  
Van Der Waals Volume ◽  
Thinning Effect

A scheme has been developed for calculating the glass transition temperature and flow temperature of plasticised polymers. The scheme takes into account the chemical structure of the polymer and plasticiser, the molecular weight of the polymer, the intermolecular interaction between the polymer and plasticiser, the van der Waals volume of the repeating unit of the polymer and the plasticiser molecule, and the plasticiser concentration. The thinning effect is also taken into account, as manifested by a reduction in the viscosity of the polymer–plasticiser system with increasing plasticiser concentration.

An Approach to Analysing the Influence of the Chemical Structure of the Solvents and their Concentration on the Glass Transition Temperature of the Polymer for Systems Containing a Polymer and Two Solvents

2017 ◽  
Vol 44 (4) ◽  
pp. 41-44
Author(s):  
T.A. Matseevich ◽  
E.A. Kurskaya ◽  
O.V. Kovriga ◽  
A.A. Askadskii
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Intermolecular Interaction ◽  
Chemical Structure ◽  
Van Der Waals ◽  
Van Der Waals Volume

A scheme has been developed for calculating the glass transition temperature of a system containing a polymer and two different solvents. Account is taken of the chemical structure of the polymer and solvents (one of them may be a plasticiser), the intermolecular interaction between the polymer and solvents, and also between the solvents themselves, the van der Waals volume of the repeating unit of the polymer and molecules of both solvents, and their concentration.

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