RESUMO
Units of 2-ureido-4-pyrimidone that dimerize strongly in a self-complementary array of four cooperative hydrogen bonds were used as the associating end group in reversible self-assembling polymer systems. The unidirectional design of the binding sites prevents uncontrolled multidirectional association or gelation. Linear polymers and reversible networks were formed from monomers with two and three binding sites, respectively. The thermal and environmental control over lifetime and bond strength makes many properties, such as viscosity, chain length, and composition, tunable in a way not accessible to traditional polymers. Hence, polymer networks with thermodynamically controlled architectures can be formed, for use in, for example, coatings and hot melts, where a reversible, strongly temperature-dependent rheology is highly advantageous.
Assuntos
Polímeros/química , Pirimidinonas/química , Dimerização , Ligação de Hidrogênio , Termodinâmica , ViscosidadeRESUMO
A 81-year-old man presented with bilateral adrenal masses found pathologically to be a large cell, non-follicular center, non-Hodgkin's lymphoma. His clinical course was remarkable for the lack of macroscopic extra-adrenal tumor and for adrenal insufficiency in response to stress and cosyntropin stimulation. This is believed to be the first reported case of a non-Hodgkin's lymphoma limited to the adrenal glands with associated adrenal insufficiency.
