Ana zincirde benzoksazin blok kopolimeri

Polybenzoxazine has gained increasing interest as one of the valuable high performance polymeric material. They present features such as near-zero volumetric change upon curing, low water absorption, for some polybenzoxazine based materials Tg is much higher than cure temperature, high char yield, release of no toxic by-product, and no strong acid catalysts required. However, polybenzoxazines synthesized from the monomer precursors suffer from some shortcomings incluiding brittleness, need of quite high temperature for curing process and poor film forming. To solve this problems, researchers study on two subjects; blending polybenzoxazines with other polymeric materials and modifying monomers with additional functionalities. In this study, to modify benzoxazines, polyetheramine derivatives were used. In general polyetheramines are used in the process of epoxy curing and they also serve stiff, impact-modified coatings, castings, and adhesives. A new method for the preparation of block copolymers of polymeric benzoxazine precursors with polyetheramines by one-pot two-step or stepwise pathways is described. The method pertains to the use of simple chemicals such as 4-hydroxyaniline, formaldehyde and polyetheramines. The structure and molecular weights of polymers were characterized by FTIR, 1H NMR and GPC. Block copolymer formation was evidenced by the clear shift of the molecular weight of the block copolymer to the higher molecular weight region. Thermal properties of the polymers were also investigated by using DSC and TGA. Block copolymers were shown to undergo thermally activated curing by the ring opening polymerization of benzoxazine block. The thermal stability of the cured product drastically increased compared to the precursor polyetheramine.