Anhydrous toluene

DHA particles were surface-modified using trimethoxy(propyl)silane
(TMPS) (Sigma-Aldrich). For this, the particles (100 mg) were kept
in a vacuum chamber at 60 °C for 24 h before being ultrasonically
dispersed in 5.0 mL of anhydrous toluene (Merck) for 30 min. The resultant
solution/dispersion was refluxed at 110 °C for 24 h while being
vigorously stirred after the addition of TMPS (4.0 mL). Following
the grafting procedure, the modified DHA (dubbed MDHA) was separated
from the dispersing solvent by centrifugation at 3900 rpm for 10 min,
thoroughly rinsed with ether to remove the physically attached silane
molecules, and dried at 60 °C for 16 h. To chemically confirm
the surface modification, we carried out FTIR analysis. Moreover,
grafting density of TMPS to particles was determined according to
the method described in the literature.^{31 (link)} The colloidal stability of unmodified and surface modified particles
was also investigated by using sedimentation experiments. The powder
was dispersed in chloroform (Fluka) at a particle loading of 1 mg/mL
using a water bath sonicator, and the suspensions were allowed to
stand for 48 h, while the particle sedimentation behavior was recorded
at various time intervals.

Cardanol-based epoxy (GX-2551, Figure 1), termed EC, was
provided by Cardolite Corporation (USA). EC was characterized by a
viscosity at 25 °C of 102 cP, while the epoxy equivalent weight
was 170 g/g equiv epoxy. Pripol 1006, dimer acid hydrogenated was
provided by Croda Coatings & Polymers (acid value 196 mg KOH/g).
Benzene-1,4-diboronic acid, 1-thioglycerol (97%), ethanol (EtOH, 96%),
and anhydrous toluene (99.8%) were purchased from Merck and used as
received unless otherwise stated. The cross-linker, namely, [2,2′-(1,4-phenylene)-bis[4-mercaptan-1,3,2-dioxaborolane]
(DBEDT), was prepared by following the procedure previously reported.^{31 (link)}