Polystyrene-block-polybutadiene-block-poly[(methyl methacrylate)-stat-(methacrylic acid)] (SB(MA)) block copolymers incorporating acid-reactive functionalities in the last block have been synthesized and studied as modifiers for epoxy thermosets based on the diglycidyl ether of bisphenol A (DGEBA). Different techniques including differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) have been used to demonstrate the effectiveness of the reaction-induced modification compared to that with the nonreactive or slowly reacting polystyrene-block-polybutadiene-block-poly[(methyl methacrylate)-stat-(tert-butyl methacrylate)] SB(MT) triblock copolymer. Morphological characteristics revealed by TEM indicate that SB(MT) and SB(MA) are both miscible with the epoxy prepolymer. The kinetics of grafting, network formation, and possibly phase separation were quantified from FT-IR, DSC, and cloud point investigations of DGEBA/ DDS (4,4′-diaminodiphenyl sulfone) as an epoxy-thermoset model system in the presence of poly[(methyl methacrylate)-stat-(methacrylic acid)] (HT121) or the block copolymers. The cure of the thermoset/block copolymer system has been explored using six different curing processes: 2-phenylimidazole (2-PI), alone or in the presence of methyltetrahydrophthalic anhydride (MTHPA) as comonomer, accelerated dicyandiamide (DICY), and three different diamines as comonomers without accelerator: 4,4′-methylenebis(3chloro-2,6-diethylaniline) (MCDEA), 4,4′-methylenedianiline (MDA), and DDS. The use of reactive block copolymers instead of nonreactive ones permits a better control of morphology. The materials' performances are analyzed in terms of transparency, glass transition temperature, T g, and linear elastic mechanics at break (critical intensity factor, KIC).

Polystyrene-block-polybutadiene-block-poly(glycidyl methacrylate) (SBG) and polystyreneblock-polybutadiene-block-poly(methyl methacrylate)-block-poly(glycidyl methacrylate) copolymers (SBMG) were synthesized by sequential living anionic polymerization in tetrahydrofuran (THF). SBMG copolymers were used as modifiers for epoxy thermosets based on the diglycidyl ether of bisphenol A (DGEBA). Different techniques including differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and optical cloud point measurements have been used to demonstrate the advantage of having a reactive copolymer to finely tune and control the morphology of nanostructured materials. The FT-IR and DSC studies were used to follow both the kinetics of reaction of the reactive block G with the epoxy-amine system and of cross-linking of the epoxy-amine system. They give an interesting insight into the problem of factors governing the expulsion of the methacrylic block out of the epoxy-amine phase during network formation. Morphological characteristics revealed by TEM appear to be closely related to the optical properties of these composites.