Understanding Stain-Surface Interactions Towards Mechanisms for Stain Removal in Fabric Care

A detailed understanding of soil–substrate interactions is increasingly critical for
advancing cleaning technologies, particularly as industries seek to replace traditional
ingredients with alternatives that combine high performance with improved
environmental profiles. Effective stain removal requires disrupting the binding of soils
to surfaces and breaking down complex mixtures, a challenge that is especially
pronounced in fabric care, where both stain diversity and fabric variability demand
precise, targeted cleaning strategies.
Chapter 1 provides the background to this work, beginning with an overview of the
historical evolution of detergents. It discusses the roles of the key classes of ingredients
used in modern detergents and how these components contribute to overall cleaning
performance. The chapter also reviews conventional techniques used to identify stains
on fabrics, highlighting both their capabilities and their limitations when applied to
complex soil systems.
Chapter 2 describes the materials, experimental procedures, and analytical methods
employed throughout this thesis. Sample preparation protocols and experimental
conditions are provided to ensure reproducibility and to contextualise the results
discussed in later chapters.
A limitation of conventional performance testing lies in its inability to capture dynamic
soil removal processes. To address this, Chapter 3 introduces a novel analytical
approach that combines infrared spectroscopy with a fluidic cell specifically adapted
for fabric care applications. This in situ method enabled real-time monitoring of soil
removal, providing mechanistic insights into the rate and progression of stain
breakdown during washing. The technique also allowed individual components within
complex stains to be identified and tracked, offering a deeper understanding of how
formulation ingredients influence cleaning performance over time.
The capabilities of this technique are applied in Chapter 4 to investigate lipid-based
stains, which represent a major class of soils encountered in domestic laundering.
Using the in situ infrared method, the removal behaviour of lipid components is
monitored in real time, enabling the interactions between stains, fabric substrates, and detergent ingredients to be examined in detail. Particular emphasis was placed on
surfactants and chelating agents, evaluating not only their individual effects but also
their synergistic or antagonistic interactions under realistic cleaning conditions.
Subsequent chapters extend this investigation to other types of stains. Chapter 5
focuses on polyphenol-based stains, examining their behaviour both in solution and
when deposited on fabrics. Special attention is given to the role of metal ions in
stabilising these stains and the mechanisms by which chelating agents can disrupt
these interactions to enhance stain removal.
Chapter 6 presents work based on a published study investigating the chlorination of
an organic sunscreen ingredient and its role in fabric discoloration. This chapter
explores the chemical mechanisms underlying the formation of chlorinated products
and their potential impact on textile appearance during laundering.
Collectively, these insights advance both the fundamental science of stain–surface
interactions and the design of more effective, sustainable fabric care solutions.