and aiding in more efficient chemical reactions. A stirrer bar is a ... facilitate chemical reactions by lowering ... The BaylisâHillman reaction, catalysed by.
Plastic waste issue
How to impregnate plastic with a catalyst?
In July 2017 it was reported the world produced over 9 billion tonnes of plastic since the 1950s, of which only approximately 9% was recycled. Annually within the UK, 3.7 million tonnes of plastic is recycled, this accounts for only 29% of plastics, and by 2020 a target of 57% has been set.1 As an institution, London Metropolitan University is at the forefront of environmental sustainability within the higher education sector, supporting myriad ‘green’ projects in recent years.2
Three methods were used to incorporate the catalyst into the plastic: firstly by swelling the filaments in solvent containing catalyst.6 The second approach involved the use of an extruder in order to extrude plastic and catalyst mixed together to produce a filament.7
3D printing Three-dimensional (3D) printing has the ability to revolutionize industrial processes. There is substantial interest in its use for industrial prototyping, the production of tissue scaffolds, and manufacturing of electronic tools.3
Figure 7 – Extruder cross section
Figure 8 – Filastruder
The final method was to recycle polymer that was previously used and fuse this together with the catalyst.
However, the full potential of this technology to transform science and technology by creating lowcost, custom-built appliances has yet to be realised. Figure 1 – 3D printing functioning scheme
Aim The aim of this project was to recycle plastic into 3D print chemical lab ware, such as stirrer bars with impregnated catalyst, thus both helping to reduce plastic waste and aiding in more efficient chemical reactions. A stirrer bar is a laboratory device that employs a rotating magnetic field to physically stir a solution to which it is immersed in.
Figure 2 – Stirring bar in action
Figure 3 – Top view of a stirrer bar action
Figure 9 – Molten plastic
Figure 10 – Plastic blended with catalyst
Figure 11 – 3D Printer used in the study
Results All three methods for impregnating the catalyst into the polymer were quantified by HPLC. The first method of swelling proved unsuccessful in loading catalyst. The second and third procedures show that catalyst was present and these were successfully printed into stirrer bars.
Figure 4 – Stirring bar tic
Chemical catalysis Catalysts are compounds which help facilitate chemical reactions by lowering their activation energy.4 By definition, catalysts facilitate chemical reactions without being consumed, however, due to the small amounts used, are difficult to recover and often discarded.
Scheme 2 – From melting plastic to printing a catalyst containing prototype
The percentage conversion of the two methods of incorporating catalyst was tested and compared against the standard conditions. O
O H
O H
DMAP impregnated into plastic
tic
DMAP powder
Extrusiona
Meltinga
72%
85%
OH
91%
Table 1 – Percentage conversion from the H-NMR of the reaction mixture
Scheme 1. Baylis-Hillman Reaction with DMAP embedded into plastic
O
O H
Figure 5 – Activation energy plot
O H
The Baylis–Hillman reaction, catalysed by DMAP 4-dimethylaminopyridine (DMAP), is a impregnated carbon-carbon bond forming reaction into plastic between the α-position of an activated 5 Scheme 1. Baylis-Hillman Reaction with DMAP alkene and an aldehyde. heme 1. Baylis-Hillman Reaction with DMAP embedded into plastic OH
embedded into plastic
Tinkercad Tinkercad is a computer aided design software that allows the design of 3D objects. Thesetic are then converted into stereolithographic files (.stl) that can be processed by the 3D printer.6 Figure 6 – Top view design and measurements of the prototype
Conclusion and future work The study has shown the possibility to recycle plastics and proved that lab ware can be created containing catalyst within its structure. As the results indicate, the reaction was successfully catalysed and the percentage of conversion (reactant to product) was close to the standard conditions. The melting technique offered the most intake of catalyst which has led to tic the highest conversion percentage (85%), compared to the other methods. Future work involves the improvement of the impregnation process, quantification of catalyst loading and the design of different stirrer bars, with the aim to increase the area of reacting surface. Furthermore, the aim will also be to extend the process to a wider range of catalysts and reactions in order to generalise this process.
Figure 12 – Future concept design of stirrer bars
References 1) British Plastic Federation (www.bpf.co.uk); 2) London Metropolitan University (www.londonmet.ac.uk/about/sustainability/); 3) 3D Pr/); 4) Catalysis (www.nature.com/subjects/catalysis), Activation Energy plot (www.opentextbc.ca); 5) Rezgui F, El Gaied M. Tetrahedron Letters 1998, 39, 5965-5966; 6) Tinting (www.3dprinting.com); 3D Function (www.safaribooksonline.com), Stirrer bar action and top side view (http://www.hsmagnets.cominkercad (www.tinkercad.com); 7) Goyanes. A, Robles Martinez. P, Buanz. A, Basit. A, Gaisford. S. International Journal of Pharmaceutics 2015, 494, 657-663; 8) Goyanes. A, Buanz. A, Basit A, Gaisford. S. International Journal of Pharmaceutics 2014, 476, 88-92.; Filastruder cross section (www.filastruder.com).
