A new AB 2 monomer, 5-amino-4-hydroxyisophthalic acid hydrochloride, was synthesized and polymerized in poly(phosphoric acid) (PPA) to afford a carboxylic acid-terminated hyperbranched polybenzoxazole (HPBO). Taking advantage of the large number of peripheral carboxylic acid groups on HPBO, polyarm-star block copolymers, HPBO-b-mPEK and HPBO-b-pPEK, were conveniently prepared in the same reaction medium with additional amounts of phosphorus pentoxide (P 2 O 5 ) via "direct" Friedel-Crafts acylation reaction with 3and 4-phenoxybenzoic acids as AB monomers. All the resulting polymers displayed polyelectrolyte behaviors in solution due to the large number of carboxylic acid termini. The UV-vis absorption intensities, which increased as polymer concentration was increased, showed quasi-linear dependence in all sample solutions. The emission intensity drastically decreased as the concentration of HPBO core polymer was increased, while the block copolymers were not much affected by concentration variation. The emission behaviors of HPBO-b-mPEK and HPBO-b-pPEK should be inherent to the chromophoric inner HPBO cores, which were shielded by the outer linear PEK shells. The morphology study suggested that both proton conductivity and optical behaviors of HPBO might be greatly influenced by the globular core-shell architecture.

Purification of diamond nanopowder (DNP) was conducted in a less-destructive mild polyphosphoric acid (PPA)/phosphorous pentoxide (P 2 O 5 ). The wide-angle X-ray diffraction (XRD) showed that the intensity of the characteristic diamond d-spacing (111) at 2.07 Ǻ from purified DNP (PDNP) was fairly increased compared to pristine DNP, indicating that significant amount of carbonaceous impurities were removed. Chemical modification of pristine DNP and PDNP with 4-ethylbenzoic acid was carried out to afford 4-ethylbenzoyl-functionalized DNP (EBA-g-DNP) and PDNP (EBA-g-PDNP). The morphologies of EBA-g-DNP and EBA-g-PDNP from scanning electron microscopy (SEM) were further affirmed the feasibility of chemical modification. The results suggested that the reaction condition was indeed viable for the one-pot purification and functionalization of DNP. The resultant functionalized DNP could be useful for nanoscale additives. Hence, EBA-g-DNP and EBA-g-PDNP was brominated by using Nbromosuccinimide (NBS). The resultant α-brominated DNP and PDNP could be used as initiator for the atom transfer radical polymerization (ATRP) to introduce many polymers onto the surface of functionalized DNP and PDNP.