#  Synthese of Diels-Alder polymers 

 



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#### Reagens

The reactants, the monomers, used in the synthesis of the reversible DA-polymer network system were purchased from Sigma-Aldrich:

- ˆ(A): 2 Jeamine D-series: Poly(propylene glycol) bis(2-aminopropyl ether) with average degree of polymerization n (determined by nuclear magnetic resonance spectroscopy): 
    - n = 44.2: J2000, Mn = 2640 g/mol
    - n = 71.1: J4000, Mn = 4200 g/mol
- ˆ(B): furfuryl glycidyl ether (FGE, 96 %)
- (C): 1,1'-(methylenedi-1,4-phenylene)bismaleimide (DPBM, 95%)

   ![Reagens used for the polymerization of the Diels-Alder network](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/srtsandbox/files/reactans.png?itok=ST0SjIzk) 

 

#### Polymerization

In this section it is explained how the DA-polymers are synthesized. J4000 and J2000 material is synthesized into sheets while J400 is synthesized into powder. For each step the chemical reaction is explained followed by a description of the practical actions required to preform this step. The following amounts of DA-polymer material was made:

- DPBM-FGE-J4000: 100x100 mm sheet with a 0.75 mm thickness.
- DPBM-FGE-J2000: 100x100 mm sheet with a 0.50 mm thickness.

#### Step 1: epoxy-amine reaction

In a first step, FGE was irreversibly bonded to Jx (x = 400, 2000, and 4000) through an epoxy-amine reaction, yielding a furan functionalized compound. This reaction was performed at 60 °C for minimum 7 days after which the reaction was completed at 90 C° (to speed up the reaction) for 2 days.

   ![Epoxy-aminer-reaction](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/epoxy_amine_reaction.png?itok=-3b1_kze) 

 

In practice: Pour the FGE and the Jeffamine together. The following amounts were used:

   ![Step 1](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/srtsandbox/files/synthesis_step_1.png?itok=IFCqEgbR) 

 

- Heat the solution using an oil bath to 60°C for minimum 7 days. Stir continuously using a magnetic stirrer.
- Increase the temperature to 90°C for another 2 days.

   ![synthesis_step_2_practice.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/synthesis_step_2_practice.png?itok=u-WJHR-g) 

 

#### Step 2: Network formation

In a second step, the furan functionalized compound (FGE-Jx) was mixed with DPBM in a stoichiometric ratio of one (r= nMaleimide / nFuran = 1) to obtain the reversible polymer network through DA reaction. Prior to the DA reaction, the DPBM was dissolved in chloroform (a 20 w% solution) to obtain a homogeneous reversible network.

   ![Network formation](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/srtsandbox/files/diels_alder_reaction.png?itok=DExa6D4D) 

 

In practice: Pour the FGE and the Jeffamine together. The following amounts were used:

   ![Step 2](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/synthesis_step_2.png?itok=0YV0-p5_) 

 

- Pour the chloroform at the FGE-Jx
- Add the DPBM to the solution
- Stir at room temperature for at least 2 hours, using a magnetic stirrer, until a completely homogeneous solution is obtained

   ![Step 1: practical](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/synthesis_step_1_practice.png?itok=pAZTNU9n) 

 

#### Step 3

The chloroform has to be evaporated out of the solution and the thermo-reversible network has to be formed. The chloroform is extracted by increasing the temperature to 60°C at vacuum. The thermo-reversible network is formed by slowly cooling down the sheet after the chloroform has been completely extracted.

In practice: The following amounts were used to develop the DPBM-FGE-Jx sheets:

- DPBM-FGE-J4000: 28.1 ml
- DPBM-FGE-J2000: 18.8 ml

Step by Step:

- 1 hour at 30°C and atmospheric pressure
- gradually increase the temperature up to 660°C
- gradually decrease the pressure up to vacuum.
- remain at 60°C and vacuum until all bells are removed
- remain for 3 days at 50°C and vacuum
- cool down slowly (5°C/hour) to ambient temperature after which the synthesis is completed

   ![synthesis_step_3_practice.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/srtsandbox/files/synthesis_step_3_practice.png?itok=hC-L-_Ww)