PHY3071 Soft Matter 2023-24
Dr P.G. Petrov
Delivery Weeks: T2:01-11
Level: 6 (NQF)
Credits: 15 NICATS / 7.5 ECTS
Enrolment: 33 students (approx)


This module will discuss important approaches for describing and understanding the behaviour and interactions in soft matter systems. In particular, topics explored in this module will include electrostatic and other interactions in solutions, random walks, conformation of (bio)polymers, diffusion processes, mechanics of soft membranes and hydrodynamic interactions in liquid films. In addition, it will introduce important experimental methods used to study soft matter systems and will discuss their theoretical bases.

Module Aims

The module will offer insights into the complex and fascinating physics of various systems generally known as soft matter. It aims to develop students' understanding of the physical principles, interactions and processes governing the behaviour of such systems and provide the necessary tools for quantitative description of their behaviour.

Intended Learning Outcomes (ILOs)

A student who has passed this module should be able to:

Syllabus Plan

  1. Introduction to Soft Matter
  2. Colloidal systems
    1. Introduction to colloids
    2. Electrostatic forces between surfaces in liquids.
      1. Electric double layer.
      2. Poisson-Boltzmann equation and the distribution of the electrostatic potential. Debye-Hückel approximation. Grahame equation.
      3. Pressure and interaction energy between two charged surfaces in aqueous solutions.
      4. Stern model of the double layer.
      5. Limitations of the Poisson-Boltzmann theory.
    3. Van der Waals interactions between surfaces.
      1. Van der Waals disjoining pressure and energy of interaction.
      2. Hamaker constant. Lifshitz theory.
    4. The DLVO theory of the stability of colloidal suspensions.
      1. The DLVO potential
      2. Effect of Hamaker constant, surface electrostatic potential and electrolyte concentration. Secondary minimum.
    5. Experimental measurement of surface forces.
    6. Beyond DLVO: hydration forces, hydrophobic interaction, steric and fluctuation forces.
  3. Diffusion processes
    1. Introduction to Brownian motion.
    2. Random walk model. Diffusion equation.
    3. Langevin equation. Einstein-Smoluchowski relation.
    4. Diffusion equation: classical approach.
    5. Solution to the diffusion equation. Laplace transform.
    6. Experimental methods for determination of diffusion coefficients.
  4. Polymers in solutions
    1. Introduction to macromolecules.
    2. Random walk model and polymer conformation. End-to-end distance and radius of gyration.
    3. Polymers in solution: frictional coefficient and diffusion.
    4. Entropic elasticity.
    5. Single molecule elasticity: experiments.
  5. Soft membranes and free liquid surfaces
    1. Amphiphilic molecules. Supramolecular self-assembly.
    2. Mechanical properties of thin membranes.
    3. Curvature of surfaces. Curvature energy and bending rigidity. Shapes of lipid vesicles and biological membranes.
    4. Thermal fluctuation spectrum of soft membranes.
    5. Experimental determination of the bending elastic modulus and the area modulus of soft membranes.
    6. Surface tension. Laplace equation.
    7. Equilibrium shapes of free liquid surfaces. Exact and approximate solutions.
    8. Experimental determination of the surface tension.
  6. Hydrodynamic interactions in thin liquid films
    1. The Navier-Stokes equations. The equation of continuity.
    2. An exact solution: Poiseuille flow.
    3. Lubrication approximation.
    4. Hydrodynamics of thin liquid films.

Learning and Teaching

Learning Activities and Teaching Methods

Description Study time KIS type
20×1-hour lectures 20 hours SLT
2×1-hour problems/revision classes 2 hours SLT
5×6-hour self-study packages 30 hours GIS
4×4-hour problem sets 16 hours GIS
Reading, private study and revision 82 hours GIS


Weight Form Size When ILOS assessed Feedback
0% Guided self-study 5×6-hour packages Fortnightly 1-11 Discussion in class
0% 4 × Problems sets 4 hours per set Fortnightly 1-11 Solutions discussed in problems classes.
100% Final Examination 2 hours 30 minutes January 1-11 Mark via MyExeter, collective feedback via ELE and solutions.


The following list is offered as an indication of the type & level of information that students are expected to consult. Further guidance will be provided by the Module Instructor(s).

Core text:

Supplementary texts:


Further Information

Prior Knowledge Requirements

Pre-requisite Modules Vector Mechanics (PHY1021), Properties of Matter (PHY1024), Electromagnetism I (PHY2021), Thermal Physics (PHY2023) and Mathematics with Physical Applications (PHY2025)
Co-requisite Modules none


Re-assessment is not available except when required by referral or deferral.

Original form of assessment Form of re-assessment ILOs re-assessed Time scale for re-assessment
Whole module Written examination (100%) 1-11 August/September assessment period

Notes: See Physics Assessment Conventions.

KIS Data Summary

Learning activities and teaching methods
SLT - scheduled learning & teaching activities 22 hrs
GIS - guided independent study 128 hrs
PLS - placement/study abroad 0 hrs
Total 150 hrs
Summative assessment
Coursework 0%
Written exams 100%
Practical exams 0%
Total 100%


IoP Accreditation Checklist
  • N/A this is an optional module
Availability unrestricted
Distance learning NO
Keywords Physics; Colloids; Soft matter; Electrostics; Random walks; Diffusion; Polymers; Liquid Films; Transport.
Created 02-Mar-16
Revised N/A