FPP3D: Coupling frontal photopolymerisation and interfacial wrinkling for single shot 3D patterning

Lead Research Organisation: Imperial College London
Department Name: Department of Chemical Engineering


The solidification of polymeric materials by light exposure is a common approach in coatings and patterning technologies. Under specific conditions, a solidification front (defined by the interface between liquid and solid) is sharp and, driven by light, travels thereby invading the unpolymerised material. Such light-driven travelling wave polymerisation processes give rise to frontal photopolymerisation which is an attractive manufacturing tool for multi-level patterns and objects. It is thus desirable that the liquid-solid front is planar and smooth. However, interfacial "roughness" may occur at certain front velocities, light intensity, temperature, time and other manufacturing conditions. This project will investigate and control this "roughness" - caused by wrinkling, folding and creasing of the interface - to manufacture functional surfaces of high value. An experimental capability map and predictive computational tool will be established and validated and then applied to rapidly prototype exemplars of this novel manufacturing approach, including optically active materials with smooth 3D profiles.

Planned Impact

Our project will provide academic and industrial opportunities that have the potential to impact positively our economy, people, knowledge and society. In terms of economic impact, our novel 3D photolithography approach has substantial potential in: Optics and Photonics manufacturing, to inexpensively rapidly prototype and fabricate customised optical components, including aspherical lenses, diffractive optical elements, arrays, optical fibre couplers; Coatings sector, via the ability to controllably and inexpensively pattern large areas down to sub-micron dimensions, and thus impart function to materials, including directional or tailored wetting/spreading, optical appearance (including refection and scattering), adhesion, and tactile properties; Maritime industries, as patterned surfaces affect drag and fouling, which can lower energy consumption; Bioengineering and medicine as patterned surfaces and scaffolds can affect cell proliferation, motility and even differentiation; General rapid prototyping industries, including for the fabrication of microreactors. The project will generate knowledge in developing and opening routes for polymer science, pattern formation, light manufacturing and an array of technology application areas. It will also develop mathematical and simulation tools to describe no-planar wave processes, including directional solidification. In terms of people, will also train highly skilled experimentalists and modellers with broad expertise in these areas and unique knowledge in frontal photopolymerisation, who will work closely with large research teams, including in our PE-CDT, BP-ICAM and programme grant members; resulting publications and presentations at conferences will affect a wide cross-section of researchers and industrialists. Finally, the project will deliver societal impact via: potentially bespoke consumer goods with advanced properties, including optical/photonic, sensorial, wetting/spreading, manufactured at low cost; sustainable manufacturing processes, rapid and low cost, allowing successive iterations and exploring a large parameter space for innovative patterning-based technologies; possible increased manufacturing capability and job creation; public and young people engagement activities, promoting the role of science and engineering in solving complex societal problems.


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Hennessy MG (2017) A minimal model for solvent evaporation and absorption in thin films. in Journal of colloid and interface science

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Vitale A (2015) A Unified Approach for Patterning via Frontal Photopolymerization. in Advanced materials (Deerfield Beach, Fla.)

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Hennessy MG (2015) Controlling frontal photopolymerization with optical attenuation and mass diffusion. in Physical review. E, Statistical, nonlinear, and soft matter physics

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Vitale A (2016) Frontal Conversion and Uniformity in 3D Printing by Photopolymerisation. in Materials (Basel, Switzerland)

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Lopez CG (2018) Microfluidic devices for small-angle neutron scattering. in Journal of applied crystallography

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Hennessy MG (2015) Role of heat generation and thermal diffusion during frontal photopolymerization. in Physical review. E, Statistical, nonlinear, and soft matter physics

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Ferretti GL (2016) Wrinkling Measurement of the Mechanical Properties of Drying Salt Thin Films. in Langmuir : the ACS journal of surfaces and colloids

Description We discovered that the coupling of polymerisation (a common solidification process in which a monomer is converted into a polymer by light) and wrinkling results in intricate 3D pattern formation. By understanding the nature of the phenomena, we have been able to carefully design and fabricate light and surface active patterns with applications ranging from lens prototyping (otherwise a lengthy and costly process) to non-wetting surfaces. We have developed several classes of theoretical models that have been validated by experiment, ranging from minimal models with 2-3 parameters to models with increasing complexity, including mass and thermal diffusion and feedback. We have introduced a 'unifying' model describing a large range of photoactive liquids and photoresists.
Exploitation Route Microfabrication and prototyping at low cost of functional optics, advanced responsive surfaces, 3d printing of optical components, decorative and functional paints and surface coatings. In particular in manufacturing by photolithography, a growing field of additive manufacturing.
Sectors Construction,Electronics,Energy,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology,Security and Diplomacy

URL http://www.imperial.ac.uk/polymers-and-microfluidics/research/fpp/
Description A novel patterning approach based on light manufacturing of polymer structures has been reported. Ongoing progress on the fabrication of optically / radiation active surfaces and surfaces with directional wetting and spreading; possible security application. An increasing number of 3D printing approaches now utilise the minimal model reported in this project to estimate process kinetics, specifically exposure times and intensities, and to guide photoresist development.
First Year Of Impact 2014
Sector Aerospace, Defence and Marine,Construction,Energy,Environment,Manufacturing, including Industrial Biotechology
Impact Types Economic

Description EPSRC pathways to impact
Amount £45,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 11/2015 
End 11/2016
Title 3D FPP patterning 
Description Powerful lithographic methods for 2d and 3d patterning 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact Functional surfaces with controlled topography and optical properties 
URL http://www.imperial.ac.uk/polymers-and-microfluidics/research/fpp/