Progress in synthesis and application of segmented polymers

Abstract

Dedicated to Prof. Dr. H. Sinn on the occasion of his 6Sh birthday SUMMARY: Tailor-made segmented polymers play a key role in the development of novel polymeric materials exhibiting unsual bulk and surface properties. As a function of molecular architectures of segmented polymers, it is possible to control polymer morphologies and to achieve property synergisms. Selected examples are presented to illustrate basic concepts and recent developments. Segmented reactive liquid rubbers, containing an immiscible silicone segment flanked by two miscible oligo(capro1actone) segments, are efficient epoxy toughening agents. In such nano-phase-separated siliconemodiied IPNs impact strength is improved without sacrlfcing dimensional stability. Compatibilized blends of segmented phenolic polyurethane and nitrile liquid rubbers produce rubber blend microphases dispersed in epoxy prepregs which are used to bond aluminum sheets in strudural laminates. Reactive blending technologies are developed to produce segmented polymers as blend compatibilizers during melt processing, e.g., of polypropylendpolyamide 6 blends. Incorporation of oligo(tetrafluoroethene) segments into various condensation polymers modifies thermal and mechanical properties as well as surface tension and gas penneabilities.

Síntese e caracterização de poliuretanos segmentados contendo blocos de peso molecular controlado. Parte 2: correlações entre morfologia e comportamentos térmico e mecânico

“…O primeiro bloco, denominado segmento flexível, normalmente possui temperatura de transição vítrea muito baixa, o que confere propriedades elastoméricas ao material na temperatura de trabalho. Nas mesmas condições, o segundo bloco, denominado de segmento rígido, normalmente possui temperatura de transição vítrea elevada e um grau acentuado de cristalinidade, o que confere resistência mecânica ao material [1] .…”