Design and synthesis of supramolecular functional benzoxazines

Dendritic macromolecules containing benzoxazine moieties are designed and synthesized using the Frechet type of ester dendritic building block via a convergent approach. Before proceeding with dendritic building synthesis, the compatibility of benzoxazine chemistry with four different types of 2,4-, 2,5-, 2,6-, and 3,5-dihydroxy benzoicacid isomers is evaluated using Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). Among isomers, 3,5-dihydroxybenzoic acid is the most compatible with benzoxazine chemistry and yields completely closed-ring benzoxazine monomer structure. Unlike 3,5-dihydroxybenzoic acid, the other three isomers show only partial ring closure or incompatibility with benzoxazine chemistry due to the existence of intramolecular hydrogen bonding between OH–O species. After finishing the model isomer study, dendritic macromolecules containing benzoxazine moieties are newly synthesized using various combinations of amine derivatives.; Benzoxazine dendrimers show much lower maximum polymerization exotherm temperatures as the generation is increased as compared to ordinary benzoxazine monomers. Especially, it is revealed that the dendritic effect on benzoxazine curing temperature is more effective for the aromatic amine based benzoxazine dendrimer than for the aliphatic amine based system. By characterizing benzoxazine dendrimers, their self-catalyzed ring opening ability is elucidated and suggests their use as a curing initiator with other benzoxazine monomers.; The dendritic multiplication effect on benzoxazine curing behavior and dynamic viscosity is further investigated using a combination of 6-[1-methyl-1-(3-phenyl(2H,4H-benzo[3,4-e]1,3-oxazaperhydroin-6-yl))ethyl]-3-phenyl-2H,4H-benzo[e]1,3-oxazine (abbreviated as BA-a) monomer with various phenolic derivatives. Another possibility is found for improving processibility by decreasing the polymerization temperature of ordinary benzoxazine monomer with control of the number of phenolic functionalities.; Benzoxazine monomers and polymers containing phenyl phosphine oxide are also synthesized and characterized to generate a novel class of functional polymers which have high char yield. Three different kinds of phosphorus containing phenolic derivatives, bis(4-hydroxyphenyl)phenyl phosphine oxide (BHPPO), bis(4-hydroxyphenoxyphenyl)phenyl phosphine oxide (BPPPO), and bis(4-hydroxyphenoxy)phenyl phosphine oxide (BPHPPO) are designed to elucidate structure-property relationships. The monomers are thermally initiated and polymerized via ring-opening polymerization. Thermogravimetric analysis indicates that phosphorylation has profound effect on increasing char yield.