THE INTERACTION OF ACRYLIC DIBLOCK-COPOLYMERS WITH ALUMINUM-OXIDE SURFACES AND THEIR APPLICATION FOR CERAMIC POWDER PROCESSING

Amphiphilic diblock copolymers were prepared by anionic copolymerization of t.-butylmethacrylate (TBMA) with methylmethacrylate (MMA) and n-butylmethacrylate (NBMA) respectively, followed by polymer analogous conversion of the TBMA-into methacrylic acid- (MAA) blocks. These materials are highly efficient dispersants for oxide and nitride ceramic powders. A series of samples with M(n) ranging from 4.000 to 135.000, and with block length ratios from 0.5 to 14 (MMA/MAA) with polydispersities close to 1.0 were obtained. The influence of total molecular weight and block length distribution of the copolymers and quality of the solvent system on their interaction with alpha-Al2O3 were studied by sedimentation, adsorption experiments and surface plasmon resonance (SPR). The acrylic diblock copolymers are adsorbed irreversibly at the alumina surface. The conformation of the adsorbed macromolecules depends on the ''quality'' of the solvent. With respect to powder dispersing efficiency, an optimum is found when the polymers consist of short anchoring and stabilizing blocks.