Dispersant Chemistry for Photo-Curable Resins, Oligomers and Monomers in 2D, 2.5D and 3D Photopolymerisation

High-solids photopolymer formulations require simultaneous control of wetting, particle-particle attraction, suspension rheology, sedimentation, optical transport and photopolymerisation. Historically, dispersant chemistry progressed from low-molecular-weight amphiphiles to oligomeric hydroxy-fatty-acid structures, polymeric anchoring agents, and increasingly defined block, grafted, branched and comb-like architectures. Public patent literature from the 1970s onward documents an important route based on ricinoleic acid and 12-hydroxystearic-acid polyesters, including polyester-polyamine and polyester-polyethyleneimine structures. Later approaches used polylactone, polyester or polyether solvating chains attached to multi-amine backbones, while controlled radical polymerisation enabled systematic AB, ABA and comb architectures. For VPP, these structural changes matter because dispersant adsorption changes agglomerate size, effective solids fraction, viscosity, yield stress, sedimentation, refractive-index contrast and absorption/scattering, thereby shifting exposure latitude, cure depth and feature fidelity. The review proposes an architecture-surface-resin-process framework for selecting and qualifying dispersants without reliance on commercial product identities. Bio-derived content is treated as an orthogonal design dimension: castor-oil-derived ricinoleate and 12-hydroxystearate chemistry provides a historically important renewable route, but renewable origin alone does not predict dispersion or printing performance.