CFU
6
Length
14 Weeks
Semester DD
Second
Historical introduction to polymer science. Definition of polymer systems. Structural and physico- chemical properties of macromolecules. Classification of polymers based on mechanical and thermal behaviour. Glass transition temperature.
Average molecular weights and their distributions. Index of polydispersity.
Step polymerization: Carothers’s theory; statistical theory; kinetics; methods of synthesis. Non linear step polymerization: gelling.
Radical chain polymerization: mechanism; velocity of polymerization; kinetic chain length; autoacceleration; chain transfer processes; molecular weight distributions; Ceiling temperature; technologies of polymerization; pseudo-living radical polymerization.
Tacticity and its influence on physical and chemical properties of polymers.
Average chain dimension: end-to-end distance, radius of gyration, contour length. Random chain conformation, Gaussian chain, average and distribution of the end-to-end distance for a Gaussian chain. Correction to the Gaussian chain model: effect of bond angle and dihedral angle on the end-to-end distance. Pentane effect. Equivalent chain, characteristic ratio, segment of Kuhn. Excluded volume effects on the size of polymers.
Thermodynamics of mixing for polymer solution. Volume fraction. Theta conditions. Flory-Huggins theory for polymer solution. Mixing gaps. Critical conditions. Binodal and spinodal curves. Introduction to polymers hydrodynamics in solution: free-draining and non free-draining chain.
Viscosity. Viscosity average molecular weight. Polymers fractioning methods: gel permeation chromatography, fractioning by selective precipitation. Dilute polymer solution. Osmotic pressure. Fibres and elastomers. Thermodynamics of elasticity. Elastomer as an entropy spring. Statistic theory of elasticity. Mechanical hysteresis of elastomer. Deformation of polymer materials: Young’s and bulk moduli, Poisson’s ratio. Stress-strain curves of a ductile polymer. Yield strength.
Laboratory: Characterization of thermoplastic polymers by differential scanning calorimetry. IR spectroscopy measurements on commercial polymer materials. Synthesis of nylon 6,10 at the hexane/water interface.
Co-teaching: Dott. Domenici Fabio
LEARNING OUTCOMES:
The course aims to provide students with the basic notions of macromolecular chemistry, dealing with the analysis of polymer properties with the tools of thermodynamics, statistics and chemical kinetics. In addition to the introduction to the main mechanisms of synthesis and properties of polymeric materials, the problem of the average conformation of a macromolecule, of the stability of polymer solutions, of the theory of elasticity will be discussed in particular. In accordance with the interdisciplinary character of the Course of Studies in Material Sciences, the contents of the course are conveyed with a chemical-physical approach. The teaching material, provided in English, intends to introduce students gradually to the language of the international scientific community. The laboratory activities, focused on methods of characterization and synthesis of polymers, have, among other things, the purpose of contributing to the student's operational autonomy, according to what is foreseen among the educational objectives of the Degree Course.
KNOWLEDGE AND UNDERSTANDING:
At the end of the course the student must has to be aware of the main issues involving the chemistry and physics of macromolecules. The memorization of a few basic notion is required, including the chemical characteristics identifying the most important classes of polymers and the type of their synthesis, and the understanding and rationalization of the fundamental properties in the mass and solution phases.