## 2 Experiment
### The Blending and Curing of BADPE with BAFDCy/BADCy/BEDCy  
In a three-necked round-bottomed flask with mechanical stirring, after adding 175 mL of tetrahydrofuran solution, 0.5 mol each of bisphenol A dipropargyl ether prepolymer and cyanate ester were added in an equimolar ratio for stirring, and then a quantitative amount of catalyst was added, and stirring continued. Finally, the resin was transferred to a round-bottomed flask and the solvent was removed via vacuum evaporation to obtain the bisphenol A dipropargyl ether/cyanate blend resin. The curing method was in accordance with the curing gradient, holding at 433 K for 2 h, warming up to 453 K for 4 h, and warming up to 473 K for 12 h, i.e., the curing process 433 K/2 h + 453 K/4 h + 473 K/12 h, and finally the cured products were naturally cooled to room temperature. The cyanate group (--OCN) undergoes a trimeric cyclisation under heat treatment (shown in Figure 4a) and the alkynyl ether group (--O--CH\({}_{2}\)--C\(\equiv\)CH) undergoes a Claisen rearrangement reaction under heat treatment to form a 1-chromene ring, which in turn undergoes a radical photopolymerization of the chromeno (as shown in Figure 4b) [14]. The chromene ring formed by the rearrangement of the alkynyl ether in the blended resin undergoes a thermal rearrangement in which the lone pair of electrons on the oxygen atom binds to the electrophilic carbon atom in the cyanate root, ionizing --O--CN on the cyanate ester molecule, which then improves the carbon atoms in the cyanate root until trimeric cyclisation and elimination of the alkynyl ether occurs to form a triazine ring (shown in Figure 4c). The difference in the curing reaction mechanism of bisphenol A dipropargyl ether and cyanate ester makes the bisphenol A diynyl ether/cyanate blend resin form an interpenetrating network structure, which is conducive to the improvement of the mechanical properties of the blended resin. Figure 3: Infrared and hydrogen NMR spectra of bisphenol A dipropargyl ether resin prepolymerization. (a, b, c, d represent the peaks of hydrogen atoms at the corresponding positions in the molecular structure). Catalytic curing of BAFDCy with different amounts of Cu(acac)\({}_{2}\)  
The addition of different mass fractions of Cu(acac)\({}_{2}\) catalyzed the curing reaction of BAFDCy. The effect was analyzed via DSC, as shown in Figure 6, and the results are analyzed in Table 2. From the results, it can be seen that the curing temperature of BAFDCy showed a decreasing trend with the increase of the mass fraction of Cu(acac)\({}_{2}\) catalyst added, and the end temperature of BAFDCy curing was lower than 463 K with the addition of a mass fraction of 0.3%. From the results, it can be seen that there was no exothermic peak of the cured BAFDCy, which indicated that it had been cured completely [30]. Figure 5: DSC plots of the BAFDCy curing reaction catalyzed by the addition of 0.1% of different catalysts. Figure 6: DSC plots of BAFDCy catalyzed by different mass fractions of copper acetylacetonate. The 0.3% Cu(acac)\({}_{2}\)-catalyzed curing of BADCy/BEDCy  
Similarly, the curing reactions of the cyanate esters BADCy and BEDCy were catalyzed with 0.3% mass fraction of Cu(acac)\({}_{2}\), and the results are shown in Table 3. It can be seen that Cu(acac)\({}_{2}\) also catalyzed the curing reactions of the two cyanate esters, BADCy and BEDCy, resulting in a significant decrease in their curing temperatures.