Adhesion of viscous liquids on packaging surfaces could lead to wastage, an increase of recycling costs, and even customers' dissatisfaction in applications related to food, cosmetics and agrochemical industries. Lubricant-impregnated surfaces (LIS) gained much attention recently over other surface functionalisation technologies due to their non-sticking response to highly viscous liquids. This work reports an investigation into anti-adhesive properties of LIS, with an emphasis on their durability. It provides an insight into the rationale design of LIS topographies in order to maximise their lubricant retention in potential food packaging applications. Femtosecond laser processing and hot embossing were employed to produce two types of topographies for LIS on stainless steel, polypropylene and polystyrene surfaces. The first type was single-scale sub-micron laser induced periodic surface structures (LIPSS), while the second one was multi-scale (MS) structures with both micron and sub-micron features. Droplet shedding characteristics of such LIPSS-LIS and MS-LIS substrates with water, milk and honey were examined under vibration and shear. The critical sliding angles at which liquid droplets attained motion on LIS were observed to be less than 32° for all investigated liquids. However, the LIPSS-LIS substrates retained their functionality even after subjecting them to severe vibration, while the MS-LIS substrates partially lost their anti-adhesive characteristics. At the same time, the MS-LIS substrates exhibited premature pinning of droplets as compared to LIPSS-LIS substrates, under shear forces. Both vibration- and shear-induced loss of lubricant impacted the MS-LIS functionality.
Bibliographical noteFunding Information:
The research work is supported by European Commission H2020 project ‘High-impact injection moulding platform for mass-production of 3D and/or large micro- structured surfaces with antimicrobial, self-cleaning, anti-scratch, anti-squeak and aesthetic functionalities’ (HIMALAIA). It is also conducted within the framework of UKIERI-DST programme on ‘Surface functionalisation for food, packaging, and healthcare applications’. The authors would like to acknowledge also the collaboration with LASEA SA, Belgium within the framework of the ESIF project “Smart Factory Hub” (SmartFub).
© 2020 Elsevier B.V.
- Femtosecond laser
- Food packaging
- Laser induced periodic surface structures
- Lubricant-impregnated surfaces
- Superhydrophobic surfaces
- Surface texturing
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry