Among the FTIR bands, the hydroxyl content and hydroxymethyl bands were among the interest as an indication of crosslinking. As can be seen from Figure , in both HL60NP and HL85NP the intensity of the bands in the hydroxyl region at 3350 cm -1 decreased compared to the corresponding uncured samples. It is also clear that as a result of hydrothermal curing of HL85NP the shoulder at 1290 cm -1 disappeared. These results unequivocally indicate that reactions consuming the hydroxymethyl groups occurred during the hydrothermal treatment. To study the stability of cured HLNPs against dissolution in aqueous alkali, the basicity of samples was adjusted up to pH 13 by adding 1 M NaOH to the colloidal dispersions. Samples were stored at room temperature for 20 days and thereafter photographed and measured for particle diameter by DLS (Figure ). With increasing pH, the color tone of the colloids became darker due to the ionization of the phenolic hydroxyl groups. However, the systems remained colloidal as indicated by minor changes in their particle sizes (Figure ). In addition, particles could be separated by centrifugation even from the highly alkaline dispersions (Figure ). Interestingly, after conditioning at pH 13, there was a slight increase in the particle diameters of both HLNP60 and HLNP85, indicating their swelling (Figure ). We chose to investigate the particles conditioned at pH 12 by SEM as the particle sizes remained unchanged and many base-catalyzed reactions can occur in this pH. As can be seen from the SEM images (Figure and), the exposure to alkaline conditions did not visibly affect the shape and size of HLNPs. In addition to the alkaline stability of the crosslinked HLNPs, these particles showed stability in organic solvents such as ethanol, acetone, THF, and DMF (Figure ), which presents opportunities for reactions in anhydrous organic solvents.