CHIMICA FISICA DELLE SUPERFICI ED INTERFACCE

Learning Objectives. The course aims to provide the thermodynamic and molecular foundations of the physical chemistry of surfaces and interfaces and to develop the ability to interpret the main interfacial phenomena. Topics include surface tension and surface free energy, adsorption, wettability, adhesion, spreading and capillarity, as well as the role of intermolecular interactions in surface properties and the stability of colloidal systems. The course also introduces the description of solid–liquid interfaces and charged surfaces, relating surface composition, structure and functionalization to the properties of materials. The principles of biointerfaces and interactions between materials and biological systems will also be introduced, developing the ability to use simple physicochemical models to interpret interfacial phenomena and understand their relevance to functional materials and environmental, energy, technological and biomedical applications.

Expected Learning Outcomes. At the end of the course, students will have acquired the knowledge and skills described by the Dublin Descriptors.

D1 – Knowledge and understanding. Students will understand the main concepts, models and principles of the physical chemistry of surfaces and interfaces, with particular reference to interfacial thermodynamics, adsorption, wettability, capillarity, intermolecular interactions, charged interfaces, colloidal systems and the principles of biointerfaces.

D2 – Applying knowledge and understanding. Students will be able to apply the main models and relationships of surface physical chemistry to qualitatively and quantitatively interpret phenomena involving adsorption, wettability, capillarity, interactions between surfaces and colloidal stability, relating surface structure and composition to interfacial properties.

D3 – Making judgements. Students will be able to assess the applicability and limitations of the main physicochemical models, identify the relevant factors for interpreting interfacial phenomena, qualitatively evaluate the influence of surface composition, structure and functionalization, and relate surface properties to potential applications in environmental, energy, technological and biomedical contexts.

D4 – Communication skills. Students will be able to describe and discuss phenomena, models and equations in the physical chemistry of surfaces using appropriate, clear and coherent scientific language. They will be able to describe phenomena involving functionalized surfaces and colloidal systems and correctly use specialized terminology, including in interdisciplinary contexts.

D5 – Learning skills. Students will be able to integrate thermodynamic and molecular knowledge to interpret interfacial systems and use specialized textbooks, teaching materials and scientific literature to independently deepen their understanding of the topics and develop the foundations for further studies in physical chemistry, materials science, nanoscience and biointerfaces.

Information for Students with Disabilities and/or Specific Learning Disorders (SLD). Students with disabilities and/or Specific Learning Disorders (SLD) may contact the relevant University services to agree on arrangements for attending classes, participating in educational activities and taking examinations, in accordance with current legislation and the regulations of the University of Catania.

The course is delivered primarily through lectures, complemented by numerical exercises in the classroom, including discussion of problems and application examples. Teaching activities are designed to connect the theoretical description and mathematical formalism with the physicochemical interpretation of interfacial phenomena.

Examples from the scientific literature and contemporary applications involving functionalized surfaces, nanostructured materials, colloidal systems, and biointerfaces will also be discussed, with the aim of developing students' ability to transfer fundamental concepts to real systems.

Basic knowledge of differential and integral calculus, chemical thermodynamics and thermodynamic functions, properties of condensed systems, and intermolecular interactions is required. Knowledge acquired in General and Inorganic Chemistry and Physical Chemistry courses is also useful.

Attendance is governed by the Academic Regulations of the Degree Programme.

Course Contents

1. Physicochemical foundations of surfaces and interfaces. Definition of surfaces and interfaces; interfaces between condensed phases and fluid–fluid and fluid–solid systems. Molecular origin of surface and interfacial properties. Gibbs surface and interfacial region. Surface and interfacial free energy. Surface and interfacial tension: thermodynamic and operational meaning. Factors affecting surface properties, including nature, composition, and temperature. Relationship between surface structure and composition and interfacial properties.

2. Curved surfaces and capillary phenomena. Surface curvature and Laplace pressure. Young–Laplace equation and applications to simple and composite surfaces. Capillary phenomena: capillary rise and depression. Kelvin equation and capillary condensation. Effect of curvature on phase equilibrium. Examples of phenomena and processes governed by capillarity.

3. Adsorption and interfacial organization. Principles of physisorption and chemisorption. Adsorption isotherms: Langmuir model and introduction to multilayer models. Adsorption at interfaces and the relationship between adsorption and surface properties. Gibbs adsorption equation. Surfactants and their behavior at interfaces. Surface monolayers and surface pressure. Principles of molecular organization and surface functionalization. Introduction to Langmuir–Blodgett films and major approaches for characterizing interfacial properties.

4. Wettability, adhesion, and spreading. Solid–liquid–vapor interfaces and contact angle. Young equation and surface wettability. Work of adhesion and cohesion. Spreading and spreading coefficient. Thermodynamic conditions for adhesion, immersion, and spreading. Hydrophilic and hydrophobic surfaces. Effects of surface roughness and heterogeneity. Wenzel and Cassie–Baxter models. Principles of superwetting surfaces. Relationship between surface chemistry and structure and wettability.

5. Intermolecular forces and surface interactions. Interaction energy and potential; potential of mean force. Boltzmann distribution and the role of thermal motion. Electrostatic and dipolar interactions. Ion–dipole, dipole–dipole, and dipole-induced dipole interactions. Molecular polarizability. Keesom, Debye, and London interactions and van der Waals forces. Short-range interactions. Introduction to hydrophobic interactions. Role of intermolecular interactions in the properties of surfaces, interfaces, and dispersed systems.

6. Solid–liquid interfaces and charged surfaces. Origin and characteristics of surface charge. Electrical double layer at solid–liquid interfaces. Helmholtz, Gouy–Chapman, and Stern models. Qualitative description of the Poisson–Boltzmann equation. Debye length and electrostatic screening. Surface potential and electrokinetic potential. Effects of pH and ionic strength on charged surfaces. Electrostatic interactions between surfaces.

7. Colloidal systems and dispersion stability. Definition and classification of colloidal systems. Origin of particle–particle interactions. Principles of DLVO theory. Electrostatic and van der Waals contributions to colloidal stability. Electrostatic and steric stabilization. Aggregation and flocculation. Effect of surface composition and functionalization on dispersion stability. Examples of colloidal systems and dispersions of chemical and technological interest.

8. Introduction to biointerfaces. Physicochemical characteristics of interfaces between materials and biological systems. Non-covalent interactions between surfaces and biomolecules. General principles of biomolecule and protein adsorption at surfaces. Role of water in surface–biomolecule interactions. Qualitative effects of surface chemistry, charge, wettability, and roughness on interactions with biological systems. General principles of surface functionalization and biocompatibility. Introductory examples of surfaces and materials in contact with biological systems.

Core Textbook

• H.-J. Butt, K. Graf, M. Kappl, Physics and Chemistry of Interfaces, Wiley-VCH, Weinheim, 2003.

Further Reading and Reference Texts

• J. N. Israelachvili, Intermolecular and Surface Forces, 3rd ed., Academic Press, London, 2011.
• G. M. Kontogeorgis, S. Kiil, Introduction to Applied Colloid and Surface Chemistry, John Wiley & Sons, Ltd., 2016.
• A.W. Adamson, A.P. Gast, Physical Chemistry of Surfaces, John Wiley & Sons, Ltd., 1997.
  

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The instructor will also provide supplementary teaching materials and, for selected topics, scientific articles and review papers. Specific chapters or bibliographic contributions may be provided for the introductory section on biointerfaces.

Assessment Procedure

Assessment consists of an individual oral examination covering the topics addressed during the course. The assessment considers the accuracy and completeness of the content, understanding of the main theoretical models and procedures, correct interpretation of equations, and appropriate use of scientific terminology. Students' ability to connect different concepts and relate theoretical aspects to phenomena and experimental evidence will also be assessed.

Examples of Questions and/or Exercises

• Intermolecular forces and interaction potentials.
• Surface free energy and surface tension.
• Young and Young–Laplace equations.
• Wettability, contact angle, and spreading.
• Adsorption and adsorption isotherms.
• Gibbs adsorption equation and surface monolayers.
• Charged interfaces and the electrical double layer.
• DLVO theory and colloidal stability.
• Surface–biomolecule interactions and principles of biointerfaces.
• Application of physicochemical models and relationships to the solution of simple quantitative problems.