## 2 Experimental Section
### Procedures of Typical AT-SCVP  
A general polymerization is described: St, VBC, EBiB, Bpy, and A (e.g., St/VBC/EBiB/Bpy = 160/80/5/2; [St]\({}_{0}\) = 3.5 M) were added to a Schlenk flask. The mixture was deoxygenated through three freeze-pump-thaw cycles and then the flask was backfilled with N\({}_{2}\). CuBr was added to the frozen solution. The flask was closed, evacuated, and deoxygenated through two additional freeze-pump-thaw cycles. An initial sample was removed via syringe and then the flask was immersed in thermostatted oil bath. Aliquots were withdrawn at intervals during the polymerization process to allow monitoring of the monomer conversion through GC with A as an internal standard. The polymerization was stopped by placing the flask in an ice bath and exposing the contents to air. The resulting mixture was diluted with THF. The mixture was precipitated into cold MeOH, collected, and dried under vacuum (\(M_{\text{n}}\) = 1500; \(D\) (_i.e._, \(M_{\text{w}}\)/\(M_{\text{n}}\)) = 1.35; conversion = 46.7%; yield = 32%). \({}^{1}\)H NMR (600 MHz, CDCl\({}_{3}\), ppm from TMS): 7.4-6.4 (br, aromatic), 5.69 and 5.19 (br, initial moiety of double bond), 4.5 (s, Ph-\(CH_{2}\)-Cl), 2.85 (s, Ph-\(CH_{2}\)-alkyl), 2.50-1.45 (br, alkyl).  
Procedures of Catalyst Phase Switching Atom Transfer Radical Self-Condensing Vinyl Copolymerization in One-Pot  
A typical polymerization, through temperature control, is described. St, VBC, EBiB, Bpy, and T (e.g., St/VBC/EBiB/Bpy = 160/80/5/2; [St]\({}_{0}\) = 3.5 M) were added to a Schlenk flask. Procedures similar to those described above were performed, except that the starting temperature was fixed at 70 \({}^{\circ}\)C. After performing the reaction for a desired period of time, the reaction mixture was transferred to a thermostatted oil bath at 110 \({}^{\circ}\)C. The polymerization was stopped by placing the flask in an ice bath and exposing the contents to air. The resulting mixture was diluted with THF and precipitated into cold MeOH; the precipitate was collected and dried under vacuum (\(M_{\mathrm{n}}=2100\); \(D=1.39\); conversion \(=42.5\%\); yield \(=31\%\)).  
A typical polymerization, through solvent polarity control, is also described. Procedures similar to those described above were performed, except that DMF (\(N\),\(N\)-dimethylformamide) was used as an internal standard. After performing the reaction for a desired period of time at 70 \({}^{\circ}\)C, degassed A was charged into the reaction mixture rapidly. After an additional few hours, the polymerization was stopped by placing the flask in an ice bath and exposing the contents to air. The resulting mixture was diluted with THF and precipitated into cold MeOH; the precipitate was collected and dried under vacuum (\(M_{\mathrm{n}}=2200\); \(D=1.42\); conversion \(=47.6\%\); yield \(=31\%\)). The fraction of branching (FB), from NMR spectroscopic analysis, and the branching index (BI), from GPC-RI and GPC-LS measurements, were estimated using Equations (1) [19] and (2) [61], respectively:  
\[FB=\frac{\textit{Number of branched unit}}{\textit{Number of branched unit}+\textit{Number of terminal unit}} \tag{1}\]  
\[BI=M_{\mathrm{n,GPC-RI}}/M_{\mathrm{n,GPC-LS}}\ \mathrm{(for\ linear\ polymer:BI=1.0;\ for\ branched\ polymers:BI<1.0)} \tag{2}\]