Partial specific volumes of methylsuccinates and poly(itaconate)s

2-Methylsuccinates are structural analogues of the repeat unit in poly(itaconate)s. Partial specific volumes (ν₂⁰) of monomethyl and dibenzyl 2-methylsuccinates and the respective poly(itaconate)s have been determined in several solvents. ν̄₂⁰ of the monomethyl species depend on the solvent. Monomethyl 2-methylsuccinate has the same value in dioxane as in bulk. On going from dioxane, to MeOH, to H₂O, ν₂⁰ decreases progressively. Dipolar interactions, hydrogen bonds (estimated as one per molecule), and dissociation of COOH (minimal effect) are discussed. Poly(monomethyl itaconate) (PMMeI) is much denser than the corresponding 2-methylsuccinate. Also, the macromolecule has a much lower ν̄₂ in MeOH than in H₂O. In H₂O PMMeI has practically the same ν₂⁰ as poly(methacrylic acid) (PMA). But hydrophobicity of the α-group (-CH₂-COO•CH₃) seems low, making PMMeI more akin to poly(acrylic acid) than to PMA. Additivity of group contributions to the molar volume are used to calculate ν̄²⁰. This calculation succeeds in predicting the correct order of ν̄₂⁰ in H₂O and MeOH both for the 2-methylsuccinate and for the poly(itaconate) (using French and Criss method, adapted here for its application also to polymers). Dibenzyl 2-methylsuccinate in dioxane or toluene has practically the same ν̄₂⁰ as bulk dimethyl succinate (larger hydrocarbon groups in the molecule have no influence on ν̄₂⁰). Poly(dibenzy itaconate) in dioxane is denser (covalent linking along the chain). Its ν̄₂⁰ is predicted accurately by group contributions from rubbery polymers.