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

Amphiphilic diblock copolymers were prepared by anionic copolymerizati on of t.-butylmethacrylate (TBMA) with methylmethacrylate (MMA) and n- butylmethacrylate (NBMA) respectively, followed by polymer analogous c onversion of the TBMA-into methacrylic acid- (MAA) blocks. These mater ials are highly efficient dispersants for oxide and nitride ceramic po wders. A series of samples with M(n) ranging from 4.000 to 135.000, an d with block length ratios from 0.5 to 14 (MMA/MAA) with polydispersit ies close to 1.0 were obtained. The influence of total molecular weigh t and block length distribution of the copolymers and quality of the s olvent system on their interaction with alpha-Al2O3 were studied by se dimentation, adsorption experiments and surface plasmon resonance (SPR ). The acrylic diblock copolymers are adsorbed irreversibly at the alu mina surface. The conformation of the adsorbed macromolecules depends on the ''quality'' of the solvent. With respect to powder dispersing e fficiency, an optimum is found when the polymers consist of short anch oring and stabilizing blocks.