2.4. Curing and thermal performance of HBPSi-R/EP
To investigate the influence of
HBPSi-R with varying terminal groups on the curing performance of epoxy
resin, the pre-polymer resin compounds were initially characterized
using isothermal differential scanning calorimetry (DSC, SeeFigure 2b ). Upon the incorporation of HBPSi-R, the DSC
thermograms exhibited a single exothermic peak resembling that of the
native EP, indicating excellent compatibility of the three types of
HBPSi-R with the epoxy/anhydride matrix. It is noteworthy that the peak
temperature slightly decreased from 165°C to 155°C, suggesting that the
inclusion of HBPSi-R does not compromise the processability of the epoxy
resin. To determine the real chemical bonding of HBPSi-R within epoxy
resin, Fourier-transform infrared (FT-IR) spectra of the cured resin
samples were performed (Figure 2d ). Obviously, a wider
stretching vibration of Si-O at 1080 cm-1 is
recognized in spectra of HBPSi-NH2/EP, HBPSi-EP/EP and
HBPSi-V/EP, meanwhile, the peak intensity of hydroxyl group is
significantly lower than that of the native EP, indicating the
consummation of residual hydroxyl groups and confirming the
participation of HBPSi-R in the copolymerization and crosslinking with
the epoxy network. X-ray diffraction (XRD, Figure S3 ) profiles
revealed that the branching structures did not influence the molecular
arrangement, thereby maintaining the amorphous crosslinked structure of
the epoxy resin.
Thermogravimetric analysis (TGA) was conducted to assess the impact of
HBPSi-R on the thermal properties of materials. Given in Figure
2c , overall, the addition of hyperbranched polysiloxanes primarily
enhanced the residual char of the materials while exerting minimal
influence on the initial decomposition and main decomposition behavior
(as indicated by the derivative thermogravimetry, DTG, shown inFigure S7 ). This improvement can be attributed to the
introduction of the inert silicon-containing component. Notably,
compared to neat EP, HBPSi-EP/EP exhibited the most substantial increase
in char residue, rising from 6.0% to 11.7%, whereas the amino and
vinyl variants showed a char residue of 9.5%. This can be attributed to
the superior uniform dispersion of HBPSi-EP within the resin matrix
compared to the other variants. The detailed curing and thermal
parameters are supplied in Table S3 .