Polyester Methacrylate Oligomer. Exhibits excellent adhesion, ultra low warpage, and hydrophobicity. It has high thermal stability, low volatility, and excellent hydrolytic resistance. Possesses superior hydrolytic resistance due to the secondary alcohol ester residues in the backbone. Shows good solubility in both aliphatic and aromatic resins. It is hydrophobic and is used as a base resin or flexibilizer to reduce stress.