Ferulic acid-based reactive core–shell latex by seeded emulsion polymerization

A recently revisited biobased styrenic monomer, acetyl-protected 4-vinylguaiacol (AC4VG), was used for the synthesis of partially biobased, functional core–shell polymers. P(S-co-BA)@PAC4VG and PBA@PAC4VG latex particles with a PAC4VG shell were prepared using a two-step seeded radical emulsion polymerization process. The P(S-co-BA) and PBA seed particles were synthesized first, and the AC4VG monomer was subsequently added as a pre-emulsion over time. The aqueous emulsion polymerizations were carried out at 10 wt% solids at 80 °C using ammonium persulfate as a radical initiator and sodium dodecyl sulfate as a surfactant. These polymerizations resulted in colloidally stable latexes with high monomer conversions (>95%). The resulting particles were 80–90 nm in diameter (intensity-average) and TEM observations revealed core–shell and partially encapsulated particle morphologies. Up to 70% of the acetoxy groups of PAC4VG in the P(S-co-BA)@PAC4VG latex were deprotected under mild basic conditions over 18 hours to produce core–shell polymers decorated with phenolic functions on their surface. This deprotection procedure did not adversely affect the particle size or colloidal stability of the latex. Finally, partially biobased phenolic networks (phenolic resins) were produced from these functional core–shell particles by crosslinking with glyoxal, a naturally-sourced dialdehyde.