1. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
High-throughput synthesis platform to enhance the development of microcapsules
E. Bauters (Flamac) and S. Cakir (PCR UGent)
Int. Conference on high-throughput materials R&D, Ghent – June

2. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Outline
Introduction
Encapsulation technologies
Automated synthesis of micro-capsules
Characterisation of micro-capsules
Case study
Conclusions
Int. Conference on high-throughput materials R&D, Ghent – June

3. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Introduction
High-throughput methods seem to be perfectly suitable for polymer research due to the fact that many parameters can be varied during polymer synthesis (e.g., monomers, catalysts, initiators, solvents and reaction conditions), processing, blending and compounding
The reproducibility of the automated reactions and their comparability with conventional laboratory experiments are also important issues and need to be tested in advance
Close collaboration between PCR-UGent and Flamac
Int. Conference on high-throughput materials R&D, Ghent – June

4. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Encapsulation technologies •
Applications –
Protection of unstable ingredients
Vitamin C, enzymes, …
Reduction of the side effect of some ingredients
Organic UV filters, …
Providing controlled release
Perfume delivery for fabric treatment, …
Using visible spheres as a marketing tool
Release of active ingredients when triggered
Self-healing materials, corrosion inhibitors, … – – –
White et al., Adv. Mater. 2009, 21, 645–649
Int. Conference on high-throughput materials R&D, Ghent – June 4

5. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Encapsulation technologies •
Micro-encapsulation by chemical methods –
Based on polymerisation or polycondensation mechanisms
Interfacial and in situ polymerisation processes gained most scientific industrial attention
and –
Important alternatives
to coacervation
Boh et al., Bioencapsulation Innovations, March 2013
Int. Conference on high-throughput materials R&D, Ghent – June 5

6. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Encapsulation technologies •
Requirements for micro-capsules –
Mechanical properties
• Robust to survive their manufacture
• Brittle to break when external trigger
Thermal stability
Resistance to solvents –
Good shelf life to insert them into formulations or materials
Int. Conference on high-throughput materials R&D, Ghent – June 6

7. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Automated synthesis of micro-capsules •
Different
types of
micro-capsules
possible
Melamine- formaldehyde shell
Polyurea shell
Polycondensation
Interfacial polymerization
Int. Conference on high-throughput materials R&D, Ghent – June 7

8. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Automated synthesis of micro-capsules •
Automated synthesis platform –
From manual synthesis to an automated protocol
Int. Conference on high-throughput materials R&D, Ghent – June 8

9. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Automated synthesis of micro-capsules •
Automated
synthesis platform
Viscous liquid
dosing unit
Powder
dosing unit
Liquid handling
& pH trimming
unit
High shear mixer
Custom-made
synthesis
reactor
Int. Conference on high-throughput materials R&D, Ghent – June 9

10. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Automated synthesis of micro-capsules
Reliability of high-throughput synthesis platform
Reproducibility of benchmark synthesis MF-microcapsules containing cyclohexane in high-throughput
Batch #
Reactor
Pre-condensate
(pH > 9)
Emulsion
pH = 5,5 ± 0.15
Polycondensate
pH = 5,15 ± 0.15 1
9.13
5.62
5.21 2
9.09
5.64
5.33 3
9.04
5.68
5.18 4
9.07
5.57
5.09 5
9.18
5.56
5.27 6
9.11
5.58
5.28
Average
9,11
5,58
5,28
St.dev
0,05
0,09
Int. Conference on high-throughput materials R&D, Ghent – June 10

11. Reliability of high-throughput synthesis platform
Particle size distribution of different batches of Cyclohexane containing MF-microcapsules
Graph 1. PSD of batch # 7
Batch #
Mean D (μm)
Average D
[v,0.1] (μm)
[v,0.5] (μm)
[v,0.9] (μm) 7
30,95
5,93
28,53
59,15 8
29,45
5,00
26,49
58,23 9
31,77
7,57
29,59
58,63 10
28,18
6,07
27,57
49,88 11
26,66
5,61
24,73
49,76
Average
29,40
6,04
27,38
55,13
St. Dev
2,06
0,95
1,87
4,86
Int. Conference on high-throughput materials R&D, Ghent – June 11

12. Reliability of high-throughput synthesis platform•
Melamine formaldehyde micro-capsules –
Impact of process parameters on size distribution
- Mixing speed
- Mixing time
Int. Conference on high-throughput materials R&D, Ghent – June 12

13. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Characterisation of microcapsules •
Overview
Nano indentation
Morphology (optical microscopy, SEM)
Particle size distribution
Leaching of active ingredients …
Int. Conference on high-throughput materials R&D, Ghent – June 13

14. Characterisation of microcapsules•
Mechanical properties –
Using nano-indentation technique
Visco-elastic properties •
Stiffness
Elasticity
Hardness –
Flat punch tip (100 µm width)
Load displacement curve
Int. Conference on high-throughput materials R&D, Ghent – June 14

15. Characterisation of microcapsules: automated•
Mechanical properties –
Melamine formaldehyde micro-capsules
 effect of size on capsule stiffness 16 14 12 10 8 6 4 2
Diameter (µm)
S (mN/µm)
Int. Conference on high-throughput materials R&D, Ghent – June 15 11

16. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Case study •
Melamine formaldehyde micro-capsules
– Encapsulation of cyclohexane
– Multi-parameter space to be optimized
Core/ shell ratio?
Shell type?
Surfactant type ?
Mixing
speed?
pH?
Temperature?
Core/surfac - tant ratio?
Int. Conference on high-throughput materials R&D, Ghent – June 16

17. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Case study
Goal
The aim of this work is to present a combinatorial approach to enhance the investigation on a variety of synthesis and process parameters for the preparation of cyclohexane containing melamine-formaldehyde microcapsules
DoE
Int. Conference on high-throughput materials R&D, Ghent – June 17

18. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Case study •
Melamine
– Recipe
formaldehyde
micro-capsules
Reactor A
• pH adjustment
(9,5 ± 0,5)
• Heating profile
• Reaction
Pre-condensate
Reactor B
• High shear mixing
• pH adjustment
(5,5 ± 0,15)
Pre-emulsion
Reactor B
• pH adjustment during pre-condendate solution to pre-emulsion
(5,15 ± 0,15)
• Heating profile
• Condensation reaction
Condensation
Int. Conference on high-throughput materials R&D, Ghent – June 18

19. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Case study •
Melamine
formaldehyde
microcapsules
Int. Conference on high-throughput materials R&D, Ghent – June 19

20. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Case study •
Melamine formaldehyde micro-capsules
Effect of surfactant and surfactant ratio on the morphology
30 µm
140 µm
290 µm 18
5 wt% Tween 20
shell/core = 1.5
5 wt% PSMA
shell/core = 1.5
2,5 wt% PSMA
shell/core = 1.5
PSMA: poly(styrene-maleic anhydride)
Tween 20: Polyoxyethylene (20) sorbitan monolaurate
Int. Conference on high-throughput materials R&D, Ghent – June 20

21. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Case study •
Melamine formaldehyde micro-capsules
Effect of surfactant on the microcapsule formation
50 µm
100 µm
PSMA/PVA (1 wt%)
core/shell=1.5
SDS/PVA (1 wt%)
core/shell=1.5
PSMA: poly(styrene-maleic anhydride)
PVA: polyvinylalcohol
SDS: Sodium dodecyl sulfate
Int. Conference on high-throughput materials R&D, Ghent – June 21

22. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Case study •
Melamine formaldehyde micro-capsules
Effect of surfactant on the microcapsule formation
30 µm
50 µm
SDS (1 wt%)
core/shell=1
PSMA/SDS (1%)
core/shell=0.5
Int. Conference on high-throughput materials R&D, Ghent – June 22

23. Case study Melamine formaldehyde micro-capsules•
Melamine formaldehyde micro-capsules
Effect of surfactant on the microcapsule formation
PSMA/Tween (1 wt%) core/shell=1.0
10 µm
50 µm
Int. Conference on high-throughput materials R&D, Ghent – June 23

24. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Conclusions • A
unique
platform
for automated
capsule
synthesis
and
characterization, allowing
– Composition screening
– Process conditions screening •
Speeding-up the complete
material
development
chain
Synthesis
Formulation
Application
Devices
Int. Conference on high-throughput materials R&D, Ghent – June 24

25. Int. Conference on high-throughput materials R&D, Ghent – 02-04 June
Acknowledgements •
Flamac –
Pieter Castelein Geoffrey Coppens Tom Parasote
Karen Verheyen
Johan Paul •
UAntwerpen •
UGent –
Dr. Dhanya Puthenmadom
Prof. Nick Schryvers –
Prof. Filip Du Prez
Dr. Guadalupe Rivero
Michel De Keersmacker (SEM)
Int. Conference on high-throughput materials R&D, Ghent – June 25