Polymer Chemistry - A Practical Approach (F. J. Davis)_43 -...

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Protocol 3. Continued 3. Remove the septum and add TBABB (see Protocol 1) (0.05 g, 0.103 mmol) to the solution whilst maintaining a positive nitrogen pressure. Once the addi- tion is complete, seal the flask with an appropriate rubber septum. 4. Stir the solution for approximately 2 min before adding freshly distilled methyl methacrylate (15 mL, 140 mmol) in a drop-wise fashion via a cannula or a gas-tight syringe to the reactor flask at a rate of approximately 1 mL/min. 5. Monitor the exotherm using a contact thermometer (attach the contact thermometer to the side of the reactor)—typical temperatures reached vary between 45 and 60 C. 6. Once the reaction has cooled to room temperature, remove an aliquot of the reaction mixture and add it to a small amount of methanol to terminate the polymerization of the aliquot. Analyse the aliquot by GPC to determine the success of the initial polymerization. 7. Add freshly distilled n -butyl methacrylate (22.5 mL, 140 mmol) in a drop-wise fashion via a cannula to the reactor flask. 8. Determine successful reinitiation by monitoring the exotherm of the second polymerization. When the reaction mixture has returned to room temperature add methanol (ca. 5 mL) in order to terminate the polymerization. 9. Purify and recover the resultant polymer by precipitation using drop-wise addition of the THF solution into the vortex walls of a rapidly stirred ten-fold excess of cold methanol (ca. 500 mL). A brilliant white fine precipitate should be produced. Filter the polymer at the pump through a sintered- glass filter funnel, transfer the solid obtained to a large watch glass and dry it in a vacuum oven at 50 C for at least 4 h. Once a consistent weight is achieved, record the crude yield. Yields 95% are typical. 10. Transfer the crude polymer into a 100 mL beaker and dissolve it in chloro- form (ca. 10–20 mL). Precipitate the polymer in the same manner as described in step 9 by drop-wise addition of the chloroform solution to a ten-fold excess of cold methanol. Filter the polymer at the pump through

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