# Influence of Monomer Sequence on the Cyclization Behavior of Poly(acrylonitrile-_co_-acrylamide)
## 2 Materials and Methods  
Acrylonitrile (99 %), supplied by Acros, was distilled before use. Acrylamide (97%), from Fluka (Buchs, Switzerland), was recrystallized from chloroform. Azobisisobutyronitrile (AIBN) used as a radical initiator was recrystallized from ethanol and stored in a dark place at \(-3\)\({}^{\circ}\)C. Dibenzyl trithiocarbonate (C\({}_{6}\)H\({}_{5}\)CH\({}_{2}\)-S-C(=S)-S-CH\({}_{2}\)C\({}_{6}\)H\({}_{5}\), BTC) was synthesized and characterized according to the known procedure [35]. Dimethylsulfoxide (DMSO, 99%) and N,N-dimethylformamide (DMF, HPLC), supplied by Fluka, was distilled under reduced pressure before use. Polymerization was performed in a 100 mL three-neck flask equipped with an overhead device with an anchor-type stirrer. A solution containing the calculated amounts of AIBN and BTC dissolved in AN and DMSO was loaded into the flask. In the batch process, AAM was added also before the beginning of the polymerization. In the semi-batch process, AAM was loaded in DMSO solution (1/1 wt) with a BYZ-810 syringe pump (Table 1). The detailed formulations are given in the Table S1, ESI. The flask was purged with argon (99.99%) for 15 min, closed, and immersed in a bath heated to 80 \({}^{\circ}\)C. At a specified time, samples were taken for analysis. The total monomer conversion was determined gravimetrically by precipitating the polymer in the excess of deionized water. Samples for analysis by attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy and differential scanning calorimetry (DSC) were prepared by dissolving the copolymer (4 wt%) in DMSO and cast onto glass substrate. The samples were then placed in the vacuum oven at 80 \({}^{\circ}\)C overnight. The resulted films were washed with water for 24 h to remove the residual DMSO, dried to the constant weight, and separated from the surface. The films with average thickness of 20-50 \(\upmu\)m were cut into pieces 20 \(\times\) 20 mm and analyzed. The average molecular weights and dispersity (D\({}_{\text{M}}\) = M\({}_{\text{w}}\)/M\({}_{\text{n}}\)) were determined by the size exclusion chromatography (SEC). The SEC measurements were performed in DMF containing 0.1 wt% of LiBr at 50 \({}^{\circ}\)C with a flow rate of 1.0 mL/min using a chromatograph GPC-120 PolymerLabs (Santa Clara, CA, USA) equipped with refractive index and with two columns PLgel 5 \(\upmu\)m MIXED B for MW range 5 \(\times\) 10\({}^{2}\)-1 \(\times\) 10\({}^{7}\). The SEC system was calibrated using narrow dispersed linear poly(methyl methacrylate) standards \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Initial Monomer Feed, mol. \%**} & \multicolumn{2}{c}{**Total \(f_{\text{AAM}}\) Loaded in**} & \multirow{2}{*}{**Process**} & \multirow{2}{*}{**Addition**} \\ \cline{2-2} \cline{5-6}  & \(f_{\text{AN}}\) & \(f_{\text{AAM}}\) & & & **Reaction, mol. \%** & **of AAM** \\ \hline
1 \({}^{*}\) & 98 & 2 & 2 & Batch & Together with AN \\ \hline
2 \({}^{*}\) & 95 & 5 & 5 & Batch & Together with AN \\ \hline
3 \({}^{*}\) & 93 & 7 & 7 & Batch & Together with AN \\ \hline
4 \({}^{**}\) & 93 & 7 & 7 & Batch & Together with AN \\ \hline
5 \({}^{**}\) & 100 & — & 15.2 & Continuous &
\begin{tabular}{c} AAM/DMSO mixture (1/1 wt) \\ was introduced with the rate of 4 mL/h during 2 h from the reaction onset \\ \end{tabular} \\ \hline
6 \({}^{**}\) & 100 & — & 10 & Continuous &
\begin{tabular}{c} AAM/DMSO mixture (1/1 wt) \\ was introduced with the rate of 2 mL/h during 2.5 h from the reaction onset \\ \end{tabular} \\ \hline
7 \({}^{**}\) & 100 & — & 10 &
\begin{tabular}{c} AAM/DMSO mixture (1/1 wt) \\ was introduced after 0.5 h from the reaction onset with the rate of 2 mL/h during 2.5 h \\ \end{tabular} \\ \hline  & & & & \\ \end{tabular}
\end{table} 
Table 1: Formulations of the RAFT copolymerization of AN and AAM. with MW ranging from 800 to 2 \(\times\) 10\({}^{6}\) g mol\({}^{-1}\). A second-order polynomial was used to fit the log\({}_{10}\)\(M\) versus retention time dependence.