1：Experimental Design and Method Selection:

The study employed intrachain FRET to monitor conformational changes in polystyrene (PS) chains in cis-decalin solutions. Two labeling strategies were used: random labeling for high molecular weight PS (Mn = 200,000 Da) and chain-end labeling for low molecular weight PS (Mn = 13,000 and 9,700 Da). The FRET efficiency was measured by the ratio of acceptor to donor fluorescence intensities (IA/IC). Viscosity measurements were also conducted to determine the critical overlap concentration C* for comparison.

2：Sample Selection and Data Sources:

PS samples with specified molecular weights were synthesized or obtained from Polymer Source Inc. Solutions were prepared in cis-decalin, with concentrations varied by adding blank PS to maintain constant dye-labeled polymer amount.

3：List of Experimental Equipment and Materials:

Equipment included a PL-GPC 120 system for molecular weight measurement, a MAPADA UV-1800 spectrophotometer for labeling ratio determination, a PTI spectrofluorometer for fluorescence spectra, and a Bruker DRX-400 spectrometer for NMR. Materials included PS, styrene, various chemicals for synthesis (e.g., CuBr, DCC, PMEDTA), and solvents like DMF and THF.

4：Experimental Procedures and Operational Workflow:

Synthesis involved chloromethylation and labeling reactions for random labeling, and ATRP with click chemistry for chain-end labeling. Fluorescence spectra were recorded with excitation at 294 nm, and viscosity was measured using reduced viscosity vs. concentration plots. Data were analyzed to find break points in IA/IC and C* from viscosity.

5：Data Analysis Methods:

The IA/IC ratio was plotted against concentration to identify conformational transition points. Viscosity data were used to calculate intrinsic viscosity and C* as its inverse. Statistical analysis involved comparing fluorescence and viscosity results.