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The synthesis of a series of u-hydroxyfatty acid (u-OHFA) monomers and their methyl ester derivatives (Me-u-OHFA) from mono-unsaturated fatty acids and alcohols via ozonolysis-reduction/crossmetathesis reactions is described. Melt polycondensation of the monomers yielded thermoplastic poly(u-hydroxyfatty acid)s [-(CH 2 ) n -COO-] x with medium (n ¼ 8 and 12) and long (n ¼ 17) repeating monomer units. The u-OHFAs and Me-u-OHFAs were all obtained in good yield ($80%) and purity ($97%) as established by 1 H NMR, Fourier Transform infra-red spectroscopy (FT-IR), mass spectroscopy (ESI-MS) and high performance liquid chromatography (HPLC) analyses. The average molecular size (M n ) and distribution (PDI) of the poly(u-hydroxyfatty acid)s (P(u-OHFA)s) and poly(u-hydroxyfatty ester)s (P(Me-u-OHFA)s) as determined by GPC varied with organo-metallic Ti(IV) isopropoxide [Ti(OiPr) 4 ] polycondensation catalyst amount, reaction time and temperature. An optimization of the polymerization process provided P(u-OHFA)s and P(Me-u-OHFA)s with M n and PDI values desirable for high end applications. Co-polymerization of the long chain (n ¼ 12) and medium chain (n ¼ 8) Me-u-OHFAs by melt polycondensation yielded poly(u-hydroxy tridecanoate/u-hydroxy nonanoate) random co-polyesters (M n ¼ 11 000-18 500 g mol À1 ) with varying molar compositions.

The volume shrinkage during polymerization of a thermoplastic modified epoxy resin undergoing a simultaneous viscoelastic phase separation was investigated for the first time by means of pressure-volume-temperature (PVT) analysis. Varying amounts (0-20%) of poly(styrene-co-acrylonitrile) (SAN) have been incorporated into a high-temperature epoxy-diamine system, diglycidyl ether of bisphenol A (DGEBA)-4,4'-diaminodiphenyl sulfone (DDS) mixture, and subsequently polymerized isothermally at a constant pressure of 10 MPa. Volume shrinkage is highest for the double-phased network-like bicontinuous morphology in the SAN-15% system. Investigation of the epoxy reaction kinetics based on the conversions derived from PVT data established a phase-separation effect on the volume shrinkage behavior in these blends. From subsequent thermal transition studies of various epoxy-DDS/SAN systems, it has been suggested that the behavior of the highly intermixed thermoplastic SAN-rich phase is the key for in situ shrinkage control. Various microscopic characterizations including scanning electron microscopy, atomic force microscopy, and optical microscopy are combined to confirm that the shrinkage behavior is manipulated by a volume shrinkage of the thermoplastic SAN-rich phase undergoing a viscoelastic phase separation during cure. Consequently, a new mechanism for volume shrinkage has been visualized for the in situ polymerization of a thermoplastic-modified epoxy resin.

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