Design of Smart Emulsions for Crop Protection Products

Daniel Kurukji, Dr. Fotis Spyropoulos, and Prof. Ian Norton

School of Chemical Engineering, University of Birmingham, Edgbaston B15 2TT

Green and sustainable chemistry/engineering is becoming increasingly important for

companies engaged in the research, development, manufacture, and distribution of chemical

products. This is exemplified by a range of large, multi-national companies embracing the

principles of green and sustainable chemistry driven by a combination of regulatory, economic,

and consumer pressures. In particular, there is a pressing need to develop clean and sustainable

ways of feeding a world population expected to grow to nine billion by 2050.

In crop protection product formulation—the topic of this EngD—efforts have been directed

toward: developing controlled-release delivery systems with encapsulated actives; reducing

organic solvent use and/or developing ‘green’ solvent systems; and using sustainable and

biodegradable materials[1],[2]

. These are broad formulation strategies envisaged to increase

environmental/biological compatibility, safety, and efficacy.

Encapsulation is a process by which an ‘active’ substance is enclosed within a material

structure, and it is applicable to food, agrochemical and pharmaceutical product design. A main

advantage of this approach is the ability to modify delivery of a substance over different time-

scales and/or in response to physical or chemical triggers. This results in applications as

diverse as food flavour delivery through to targeted drug delivery and crop protection. Aside

from function, encapsulated products can also improve the safety and handling of otherwise

hazardous or physically/chemically sensitive materials.

Approaches to encapsulation often depend on the formation of an emulsion—this enables

encapsulation of a wide range of substances (e.g., hydrophilic, hydrophobic, etc), via a number

of ‘encapsulation vehicles’ (e.g., capsule, matrix, etc), and using a variety of synthetic and bio-

based materials (e.g., synthetic and/or natural polymers).

Emulsions are generally classed as dispersions of one phase in another immiscible phase (e.g.,

oil-in-water). The dispersed phase droplets can be at sizes ranging from 10s of nanometres

through 10s of millimetres. All of these systems are stable in a kinetic sense (disregarding

micro-emulsions), which means that over time they will revert back to a more stable,

energetically favoured state. This reversion can occur by different mechanisms, both

simultaneously and at different rates, depending on the material properties of the system and

the physical conditions. When designing an emulsion for industrial application, therefore, it is

essential to understand and control how microstructure will change over time as a result of

these destabilisation mechanisms. This encompasses understanding how to control both

process and materials to produce microstructure.

This EngD involves three partners: the University of Birmingham, Syngenta, and the National

Physical Laboratory (NPL). A broad aim of the research is to develop systems for controlled-

delivery of crop-protection products. This poster will outline the project background and

objectives, along with examples relating to nano-emulsions and encapsulation.

Figure 1: SEM of chitosan nano

emulsification (via a

and mechanical stirring (lower

chitosan spheres prepared by each method (right)

Acknowledgements

This project is co-funded by the Technology Strategy Board.

to Pat Mulqueen (Syngenta), Phil Taylor (Syngenta), Charles Clifford (NPL), and Helen

Sharman (NPL) as project partners

References

[1] I.M. Shirley, H.B. Scher, R.M.

“Delivery of biological performance via micro

Management Science, 57(2): 129

[2] P. Mulqueen, "Recent advances in agrochemical formulation"

Interface Science, 106: 83-107

[3] L.Y. Yang, G.H. Ma, Z.G.

membrane emulsification technique and application as a carrier of protein drug

Controlled Release, 106(1-2): 62

SEM of chitosan nano-spheres prepared by membrane

via a W/O emulsion template) technique (upper

and mechanical stirring (lower-left); DLS particle size analysis of

chitosan spheres prepared by each method (right)[3]

.

funded by the Technology Strategy Board. Acknowledg

to Pat Mulqueen (Syngenta), Phil Taylor (Syngenta), Charles Clifford (NPL), and Helen

as project partners.

, R.M. Perrin, P.J. Wege, M. Rodson , J.L. Chen

“Delivery of biological performance via micro-encapsulation formulation chemistry”

57(2): 129-132, 2001

"Recent advances in agrochemical formulation" Advances in Colloid and

107, 2001

, Z.G. Su , "Preparation of uniform sized chitosan microspheres by

membrane emulsification technique and application as a carrier of protein drug

2): 62-75, 2005

spheres prepared by membrane

W/O emulsion template) technique (upper-left)

left); DLS particle size analysis of

Acknowledgement is also given

to Pat Mulqueen (Syngenta), Phil Taylor (Syngenta), Charles Clifford (NPL), and Helen

Chen, A.W. Rehmke,

encapsulation formulation chemistry” Pest

Advances in Colloid and

"Preparation of uniform sized chitosan microspheres by

membrane emulsification technique and application as a carrier of protein drug” Journal of