Dr. Richard J. Spontak
Chemical and Biomolecular Engineering
CHE 761 Polymer Blends and Alloys
3 Credit Hours
Many polymeric systems of commercial relevance consist of multiple polymeric species. As a result, most of these materials are multiphase, in which case the components segregate sufficiently to endow the system with the properties of each component. In this course, we begin with a brief review of some important concepts in polymer thermodynamics and use these concepts to describe equilibrium phase behavior. Methods for calculating, and measuring properties at, equilibrium will be described. Intrinsic limitations on polymer blending will lead to a discussion of physical and chemical methods by which such limitations can be overcome, including emulsification and reactive processing. Another means by which to produce multiphase polymeric materials is through the design of copolymers. This class of materials yields the formation of nanostructures in the same fashion as surfactants, and the ordering phenomena that occur in these systems will be discussed. Thermodynamic models designed to predict the phase behavior of such materials, as well as salient characterization methods (e.g., microscopy and scattering), will be described. Topics related to interfacial characteristics, measurement and modification will likewise be addressed.
Undergraduate courses addressing (i) the thermodynamics of phase equilibria and (ii) organic/polymer chemistry.
An introductory course on polymer science would prove highly beneficial, but is not required.
Knowledge of a computer language (Fortran or C++) would be useful, but is not required.
Students will be able to:
- Predict and measure the phase behavior of multi component polymer systems at conditions of equilibrium.
- Identify blends of commercial importance, as well as the properties that make such blends important.
- Design modified polymer blends with specific morphologies and/or properties through the rational use of compatibilization methods.
- Measure and predict the phase behavior and properties of copolymers that self-organize.
- Employ natural and directed self-assembly paradigms developed for block copolymers and their blends to generate tailored nanostructures/superstructures.
- Deliver concise critiques of the scientific literature and propose new research ideas.
- Use some of the theoretical concepts introduced in lecture by engaging in a computer project.
1.Review of fundamental principles in polymer science
Polymer chains and entanglement
Conformations, mesomorphism and crystallization
Characteristic length and time scales
Chain dynamics in solutions and melts
2.Commercially important multiphase polymers and their properties
Engineering and high-temperature thermoplastic systems
Thermoplastic elastomer systems
General properties and applications
Trade names versus chemical names
3.Factors governing phase equilibrium in multiphase polymer systems
Definition, measurement and prediction of interfacial tension
Review of the classical Flory-Huggins theory and its various extensions
Overview of emerging thermodynamic frameworks developed for multiphase polymers
Phase separation mechanisms and morphology/property design
Microphase versus macrophase separation
4.Measurement and estimation of the Flory-Huggins χ interaction parameter
Introduction and applications of light, x-ray and neutron scattering
Use of the random-phase approximation to extract χ
Calculation of χ for random copolymers and their blends
Estimation of χ from solubility parameters and group-contribution methods
Dependence of χ on composition, molecular architecture and hydrostatic pressure
5.Role of chemically specific interactions on polymer phase behavior
Systems exhibiting lower critical solution behavior and their properties
Identification of chemically specific interactions in multiphase polymers
Design of polymer blends that undergo exothermic mixing
Novel opportunities for exploiting specific interactions
6.Methods to achieve compatibilization: emulsification and reactive blending
Basic principles of emulsification and reactive blending
Requirements of macromolecular surfactants relative to interfacial strengthening
Kinetic- versus diffusion-limited reactive blending
Important examples of commercial systems obtained through these routes
7.Utility of block copolymers and their blends
Prediction and characterization of block copolymer phase behavior
Factors governing the morphology and property development of block copolymers
Response of block copolymers to homopolymer or solvent additives
Contemporary uses of block copolymers as templates and membranes
Molecular thermodynamics of self-ordering copolymer molecules
8.Factors affecting the interface in polymer blends, alloys and copolymers
Classification of polymer interfaces on the basis of symmetry
Effects of chain ends, polydispersity and segment distribution on interfaces
Factors governing, and properties endowed by, interfacial curvature
Measurements designed to elucidate the structure/properties of polymer interfaces
9.Contemporary issues in the field of multiphase polymer systems
Selected to introduce students to emerging technologies that employ multiphase polymers or analytical techniques designed to facilitate the study of such materials.
10.Critical reviews of the current literature
1 take-home exam; Final exam
Take-home examination 35%
Non-comprehensive final examination 35%
Literature critiques (2) 20%