Molecular Origins of the Physical Sensation of Squeakiness
Lead Research Organisation:
University of Bristol
Department Name: Chemistry
Abstract
Procter & Gamble, one of the world's largest multinational consumer goods companies, leads the washing-up detergent market in countries such as the US and the UK with their well-renowned brands 'Tide' and 'Fairy Liquid', respectively. Well-earned; the products exhibit longer lifetimes and greater cleaning power than many of their competitors. However, P&G have failed to win majority in the Japanese market due to an unusual physical phenomenon - squeakiness. This squeaky sensation or 'kyu-kyu' marks the unique selling point of P&G's leading competitor, Kao - "Cleanness you can feel with your fingertips".
Consequently, P&G have recognised the importance of identifying and understanding the scientific origins of this sensation with two particular outcomes in mind:
1. That the findings can be translated into a method of high-throughput testing product formulations.
2. That the findings may have direct implications on the formulations themselves.
The physical sensation of squeakiness represents the interplay of a number of complex systems and their associated environmental conditions. Such systems comprise the presence and structure of skin lipids in the stratum corneum of the fingertip and the resulting interface with the aqueous-mediated surfactant layer present on the surface of the cleaned dishes. The molecular architecture of the detergent's surfactants both in the bulk aqueous phase and the surface of the cleaned dishes are in turn modified by the pH and hardness of the water, and the concentration of the product in solution.
The audible squeaking sound is believed to originate from the intermittent, jerking motion of two surfaces sliding over each other otherwise known as the 'stick-slip' phenomenon. This frictional phenomenon between surfaces can be examined with the use of two powerful instruments; the AFM and the SFA. While these instruments offer insight to the frictional forces generated at a given interface, the molecular architecture of the surfactant mixtures can be further probed as a function of concentration, pH, water hardness and composition with the use of other experimental techniques such as SANS, XRR and XPS.
Through careful consideration of the environmental and physical contributions to the surfactant structures present in the bulk and surface of the aqueous mixtures (liposomes, micelles, monolayers, and partial bilayers), the implications of the varying resultant structures on the frictional forces may subsequently be observed.
On inspection of the molecular architecture at hand the origins of frictional squeakiness may be determined. It is on ascertainment of such knowledge that a formulation may be tailored to promote squeakiness as desired.
Consequently, P&G have recognised the importance of identifying and understanding the scientific origins of this sensation with two particular outcomes in mind:
1. That the findings can be translated into a method of high-throughput testing product formulations.
2. That the findings may have direct implications on the formulations themselves.
The physical sensation of squeakiness represents the interplay of a number of complex systems and their associated environmental conditions. Such systems comprise the presence and structure of skin lipids in the stratum corneum of the fingertip and the resulting interface with the aqueous-mediated surfactant layer present on the surface of the cleaned dishes. The molecular architecture of the detergent's surfactants both in the bulk aqueous phase and the surface of the cleaned dishes are in turn modified by the pH and hardness of the water, and the concentration of the product in solution.
The audible squeaking sound is believed to originate from the intermittent, jerking motion of two surfaces sliding over each other otherwise known as the 'stick-slip' phenomenon. This frictional phenomenon between surfaces can be examined with the use of two powerful instruments; the AFM and the SFA. While these instruments offer insight to the frictional forces generated at a given interface, the molecular architecture of the surfactant mixtures can be further probed as a function of concentration, pH, water hardness and composition with the use of other experimental techniques such as SANS, XRR and XPS.
Through careful consideration of the environmental and physical contributions to the surfactant structures present in the bulk and surface of the aqueous mixtures (liposomes, micelles, monolayers, and partial bilayers), the implications of the varying resultant structures on the frictional forces may subsequently be observed.
On inspection of the molecular architecture at hand the origins of frictional squeakiness may be determined. It is on ascertainment of such knowledge that a formulation may be tailored to promote squeakiness as desired.
People |
ORCID iD |
| Wuge Briscoe (Primary Supervisor) | |
| Charlotte Kenton (Student) |