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

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

What will be covered









Waste Water Treatment

Using Microwaves to Synthesise PNIPAAM

  • 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.

Why do this?

Figure 2

Figure 1


  • 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 3

Smart Polymers

Aims and Objectives

Future Improvements

Effects on Arsenic Water

Literature Review

Structual Analysis

Assess the Benefits of Microwaves

Synthesise PNIPAAM

Figure 4

  • 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.

Method - Synthesis

Figure 5

Free Radical Synthesis

  • 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'.

Figure 6

Free Radical Synthesis

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

Method - Seperation and Purification

  • 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.

Method - Analysis

Figure 7

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

Microwave - 55°C

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

Microwave - 85°C

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

Microwave - 70°C

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

Conventional - 70°C


Figure 9

Figure 8

Microwave - 85°C (20 minutes)

Microwave - 70°C (40 minutes)

Figure 11

Figure 10

Conventional - 70°C

Figure 12

C & D

C & D

Expected - NIPAAM


Figure 13

Expected - PNIPAAM


Figure 14

A & B

Expected - Cysteamine Hydrochloride


Figure 15

Figure 16

Microwave - 85°C (60 minutes)

Microwave - 70°C (40 minutes)

Proton NMR


Figure 18

Figure 17

Conventional - 70°C

Proton NMR


Figure 20

Figure 19

Carbon Dioxide (CO2)?

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

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)?

Microwave - 75°C (20 minutes)

Microwave - 75°C (60 minutes)

Infrared Spectroscopy


Figure 24

Figure 23

Figure 22

Figure 21

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


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

Variation and Bias

What's left?

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


Need to perform dialysis on compounds and measure the yield.


Still need to check GPC results, DSC and TGA.

Technical Analysis




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


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.

Microwaves are producing far less variation but less product.



Any Questions?

Thank You For Listening!

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