Source of founding: National Science Centre
Project menager/ principal investigator: Arkadiusz Gradys,Ph.D.
Significance of the project
In recent decades, it may be observed an increasing scientific and practical interest in studies on confinement effects, which manifest, with decrease in size, as deviations in the behavior as observed in bulk. Depending on system geometry, various confinement effects may be observed. One of important issues relates to the effects in phase transitions and structure formation.
Research Project Objectives
The objective of the project is to explore physical phenomena at sub-micrometer scale, specifically, to study confinement effects on phase transitions and structure properties. It is proposed to perform experimental investigations on confinement effects in quasi-one dimensional geometry- an issue which is, as yet, not well studied. The term “quasi one-dimensional geometry” is understood as fiber / rod geometry, meaning that restriction in size is realized in two dimensions, the third dimension being considered as macroscopic.
In the frame of the project, it is proposed to investigate confinement effects on thermodynamic and kinetic parameters of phase transitions - crystallization, melting and glass transition, as well as on structure properties and its orientation. The studies will be performed using model well defined crystallizable substance consisting of linear regular chain molecules of short length unable to entangle – an oligomer. In this way, the investigated confinement effects will have only external geometrical origin, without influence of the effects resulting from constrains related with entanglement, what is typical for long chain polymers. Condition of quasi one -dimensional geometry will be provided by direct encapsulation of a model substance inside fibers obtained by coaxial electrospinning process. The key confinement parameter, which is fiber internal thickness, will be controlled by electrospinning process parameters as well as conditions of thermal treatment of as-spun fibers.
There exist confinement effects in quasi one-dimensional geometry and critical sizes of confinement leading to deviation in the kinetics of phase transitions, due to restrictions in molecular mobility and diffusion, and deviation of thermodynamic parameters due to decrease in entropy related with increase in orientation of molecules and supermolecular structure, in comparison to parameters of macroscopic (bulk) systems.