Polymer Science and Engineering

At the end of this learning unit, the student is able to :

• Determine the parameters required to model a macromolecular chain by a freely-jointed chain model, a wormlike model, or a model of rotational isomeric states; explain using statistical physics how these parameters vary with molar mass, temperature or chemical nature of the repeat unit;
• Use statistical physics and a freely-jointed chain model to compute the retraction force resulting from increasing the distance between the chain ends of a polymer chain; explain the main characteristics of this force; derive the stress/strain curve of a rubber band, starting from equations describing the statistical behavior of its chain segments, and from the environmental constraints of the experiment;
• Describe phenomenologically the glass transition of polymers and the relaxation phenomena associated with it, on the basis of the notion of free volume. Use this approach to explain how the glass transition is sensitive to the temperature and the rate of measurement;
• Describe the morphology of a semicrystalline polymer at different scales, and draw a scheme of this morphology; state how this morphology controls the properties of the material; enumerate the parameters which control the melting temperature of a polymer; derive the equation relating this melting temperature and the lamellar thickness; list the main experimental facts that must be included in any theory of polymer crystallization, and present briefly some kinetic theories able to explain these facts;
• Derive the principle of time/temperature equivalence for the elastic modulus of polymers, and describe its practical consequences for the use of such materials; quantify these effects by the Williams-Landel-Ferry equation;
• Define and explain different concepts related to the molecular structure of polymers (topology, repeating units linking, configurational structures, average molecular weights and dispersity) ;
• Describe and explain the mechanisms of the main methods of polymer synthesis : chain-reaction polymerizations (free radical polymerization, controlled radical polymerizations, coordinative polymerization and ionic polymerizations) and step-reaction polymerization; list and give the impact of the main parameters that govern the kinetics for each polymerization method ; establish relations between the polymerization method and the resulting molecular characteristics (architecture of the chain, regioselectivity, tacticity, molecular weight distribution, ') of the polymer chains;
• Describe the structure of the main types of copolymers (random, alternating, graft and block copolymers) and discuss about the synthesis method and conditions in which each type of copolymer can be obtained; predict and justify the global composition of random copolymers based on the reactivity ratios of a given couple of monomers ;
• Select and describe an appropriated polymerization method of a given monomer in order to obtain a polymer with specific molecular characteristics ;
• Describe different polymerization processes (bulk polymerization, polymerization in solution, in suspension, in emulsion and interfacial polymerization) and state the advantages and drawbacks of each process.