K2054446 Abdulla Al-Janaby

A Green Route to the Preperation of Thermoresponsive Polymers for Pharmaceutical Applications

by Abdulla Al-Janaby (K2054446)Co-supervised by Prof. Barker and Dr. Barton

START

Index

What will be covered

Aims

Method

Introduction

Results

Discussion

Conclusion

Introduction

Using Microwaves to Synthesise PNIPAAM

Waste Water Treatment

Why do this?

• Conventional methods are slow and environemntally unfriendly [1-2].
• Microwaves have faster reaction times, direct heating, provide higher yields, higher purities, improved reproducability, and energy savings [1-2].
• Poly(N-isopropylacrylamide) (PNIPAAM) is a 'smart' polymer with applications in biology, medicine, material science and water treatment [4, 6, 10].
• 1 in 3 people globally don't have access to clean drinking water [6].
• Ultrafiltration costs more than $2.9 million [7].
• Pollution and deregulation have resulted in heavy metal contamination of water.

Microwaves

• Non-ionising direct heating [8-9].
• Employ an electric and magnetic compnent which aligns dipolar molecules with the rotation of the magnetic field [8-9].
• The rotating particles can also produce heat and therefore the rate of heating depends on the solvent being used [8-9].
• Ethanol and ethylene glycol are amongst the most rapidly heating solvents whilst water, hexane and acetone are amongst the lowest. [8-9].
• The weak energy of microwaves means intramolecular bonds and hydrogen bonds are often harder to break [8-9].
• Very expensive, limited space and equipment malfunction.

Figure 1

Figure 2

Microwaves

Smart Polymers

Figure 3

Aims and Objectives

Assess the Benefits of Microwaves

Structual Analysis

Synthesise PNIPAAM

Effects on Arsenic Water

Future Improvements

Literature Review

Method - Synthesis

• I attempted both microwave and conventional synthesis.
• Dissolved N-Isopropylacrylamide (NIPAAM) - the monomer, cysteamine hydrochloride - the chain transfer agent, 2,2'azobisisobutyronitrile (AIBN) - the initiator in ethanol.
• Added a magnetic stirrer for homoginisation and to prevent cage reactions.
• All of this was done under a Nitrogen environment.
• Set a range of specified times and temperatures.

Figure 4

Free Radical Synthesis

Figure 5

• Allows for the formation of high molecular weight polymers in a relatively short amount of time without the need of relatively demanding conditions [5, 10].
• An initiator species with a reactive centre becomes activated (R.) through some sort of decomposition (e.g. thermal) [5, 10].
• Adds onto the unsaturated monomer by attacking the π-bonds to form a new radical in a process known as 'propagation' [5, 10].
• Ultimately, the process ends by the annihilation of the radical in a process termed 'termination'.

Free Radical Synthesis

Figure 6

Method - Seperation and Purification

• Rotatory evaporator
• Diethyl ether
• Vacuum desiccator
• Membrane dialysis
• Freeze drying

Method - Analysis

• Cloud point - visual inspection coil-to-globule reaction which occurs at the LCST.
• Differential Scanning Chromatography (DSC) - to give a quantifiable reading of the LCST and glass transition temperature.
• Thermogravimetric Analysis (TGA) - to assess the thermal stability of a material.
• Fourier-transform infrared spectroscopy (FTIR) - to check for organic groups formed.
• Proton Nucleac Magnetic Resonance - can be used to determine the basic structure, composition and purity of the polymer.
• Gel Permeation Chromatography (GPC) - to assess the polydispersity of my sample.

Results

Microwave - 70°C

Conventional - 70°C

Microwave - 55°C

Completed under a range of times: 10, 20, 40, 60, 180.

A standard 24 hour synthesis using a hot plate as the source of heating.

Completed under a range of times: 20, 40, 60, 120, 180.

Microwave - 85°C

Completed under a range of times: 20, 40, 60.

Figure 7

Microwave - 70°C (40 minutes)

Microwave - 85°C (20 minutes)

Figure 8

Figure 9

Conventional - 70°C

Figure 11

Figure 10

Results

Expected - NIPAAM

C & D

Figure 12

C & D

Results

Expected - PNIPAAM

Figure 13

Results

Expected - Cysteamine Hydrochloride

Figure 14

A & B

Results

Proton NMR

Microwave - 85°C (60 minutes)

Microwave - 70°C (40 minutes)

Figure 16

Figure 15

Results

Proton NMR

Conventional - 70°C

Figure 18

Figure 17

Results

Infrared Spectroscopy

Microwave - 75°C (20 minutes)

Microwave - 75°C (60 minutes)

Alkane (-C-H)?Carboxylic Acid (-C(O)-O-H)?

Carbon Dioxide (CO2)?

Alkene (=C-H)?Carboxylic Acid (-C(O)-O-H)?

Alkyne (≡C-H) ?Alcohol (-C-O-H)? Carboxylic Acid (-C(O)-O-H)? Primary Amine (-C-N-H)?

Figure 19

Figure 20

Issues

• Cage Reactions
• Oxygen
• Non-living
• Tacticity
• Regioisomerism

Figure 23

Figure 22

Figure 21

Figure 24

Variation and Bias

• Knowledge
• Human error
• Impurities
• Machine defects
• Aging and contamination of equipment
• Quality control
• Measurement bias
• Selection bias

Results

What's left?

Technical Analysis

Yield

Efficiency

Still need to check GPC results, DSC and TGA.

Need to perform dialysis on compounds and measure the yield.

Need to compare efficiency of the microwave to conventional methods as well as the polymers ability at removing arsenic from water.

Discussion

Interpretation

Relevance

Limitations

Future

Difficulty accessing equipment, budgeting and limited time.

A great way of assessing the optimal microwave conditions and whether its a viable option for future work.

Improving structure of polymer, adding comonomers, testing in other fields.

Microwaves are producing far less variation but less product.

Thank You For Listening!

Any Questions?

References

• [1] P. Unnikrishnan, Srinivas D. - CATALYTIC CONVERSION OF CO2 INTO FUELS AND CHEMICALS: A GREEN CCU OPTION. Apple Academic Press eBooks. 2014 Jul 1;186–249.

• [2] Kappe CO. Controlled Microwave Heating in Modern Organic Synthesis. Angewandte Chemie International Edition. 2004 Nov 26;43(46):6250–84.

• [3] Xu X, Bizmark N, Christie KSS, Datta SS, Ren ZJ, Priestley RD. Thermoresponsive Polymers for Water Treatment and Collection. Macromolecules. 2022 Mar 2;55(6):1894–909.

• [4] Schild HG. Poly(N-isopropylacrylamide): experiment, theory and application. Progress in Polymer Science. 1992 Jan;17(2):163–249.

• [5] Liu YM, Ju XJ, Xin Y, Zheng WC, Wang W, Wei J, et al. A Novel Smart Microsphere with Magnetic Core and Ion-Recognizable Shell for Pb2+ Adsorption and Separation. ACS Applied Materials & Interfaces. 2014 Jun 13;6(12):9530–42.

• [6] World Health Organization. 1 in 3 people globally do not have access to safe drinking water – UNICEF, WHO [Internet]. World Health Organization. 2019. Available from: https://www.who.int/news/item/18-06-2019-1-in-3-people-globally-do-not-have-access-to-safe-drinking-water-unicef-who

• [7] Guo T, Englehardt J, Wu T. Review of cost versus scale: water and wastewater treatment and reuse processes. Water Science and Technology. 2013 Nov 11;69(2):223–34.

References

• [8] Nain S, Singh R, Ravichandran S. Importance of Microwave Heating In Organic Synthesis. Advanced Journal of Chemistry-Section A [Internet]. 2019 Jan 30;94–104. Available from: http://www.ajchem-a.com/article_82193_f51dc643d1bc2b973c4fa68477201f48.pdf

• [9] Love W. Factors to consider when choosing a laboratory microwave [Internet]. [cited 2024 Feb 23]. Available from: https://www.laddresearch.com/lanotattachments/download/file/id/252/store/1/choosingmicrowaveoven_2.pdf

• [10] ALSamman MT, Sotelo S, Sánchez J, Rivas BL. Arsenic oxidation and its subsequent removal from water: An overview. Separation and Purification Technology [Internet]. 2023 Mar 15 [cited 2023 Jan 16];309:123055. Available from: https://www.sciencedirect.com/science/article/pii/S1383586622026120

• [Figure 1] MARS 6 - Microwave Digestion System [Internet]. cem.com. [cited 2024 Feb 23]. Available from: https://cem.com/uk/mars-6?___store=uk&___from_store=en

• [Figure 2] Biotage. Initiator+ Robot Eight Microwave Synthesis [Internet]. www.biotage.com. [cited 2024 Feb 23]. Available from: https://www.biotage.com/initiator-robot-eight-microwave-synthesis

• [Figure 3] Hemery G. Synthesis of magnetic and thermosensitive iron oxide based nanoparticles for biomedical applications [Internet]. hal.science. 2017 [cited 2024 Feb 23]. Available from: https://hal.science/tel-01661602/

• [Figure 7] Odian G. PRINCIPLES OF POLYMERIZATION Fourth Edition [Internet]. 2004. Available from: https://www.eng.uc.edu/~beaucag/Classes/Properties/Books/George%20Odian%20-%20Principles%20of%20Polymerization-Wiley-Interscience%20(2004).pdf

References

• [Figure 13] Tang Y, Dubbeldam D, Tanase S. Water–Ethanol and Methanol–Ethanol Separations Using in Situ Confined Polymer Chains in a Metal–Organic Framework. ACS Applied Materials & Interfaces. 2019 Oct 10;11(44):41383–93.

• [Figure 19] Liu X. 6.3 IR Spectrum and Characteristic Absorption Bands [Internet]. kpu.pressbooks.pub. 2021. Available from: https://kpu.pressbooks.pub/organicchemistry/chapter/6-3-ir-spectrum-and-characteristic-absorption-bands/

• [Figure 20] Norooz Oliaee J, Dehghany M, McKellar ARW, Moazzen-Ahmadi N. High resolution infrared spectroscopy of carbon dioxide clusters up to (CO2)13. The Journal of Chemical Physics. 2011 Jul 28;135(4):044315.