Coniferyl alcohol (G monomer) and a mixture of coniferyl alcohol/sinapyl alcohol (GS monomers, 1/1 ratio) were polymerized to dehydrogenation polymers (DHPs) in presence of two structurally related heteroxylans (HX) differing only in their phenolic substitution patterns. One (HX-40) was enriched in ferulate (FA) while the other (HX-90) was almost devoid of FA. The morphology of the resulting nanoparticles was studied by transmission electron microscopy whereas formation of particles was followed by size exclusion chromatography with online multiangle laser light scattering. HX-40-DHP-G- and HX-40-DHP-GS-derived particles display complex morphological patterns whereas HX-90-DHP-G and HX-90-DHP-GS present rather spherical shapes. The determination of particle sizes and molar masses showed that HX-90 samples formed denser particles than HX-40 ones. These differences are discussed in relation to the ferulate substitution level.