Manipulating the antioxidative capacity of melanin-like nanoparticles by involving condensation polymerization

Melanin is ubiquitous in nature and plays important roles in physiological activities especially in keeping the oxidative balance.Both natural and synthetic melanin were synthesized via the free radical polymerization of 5,6-dihydroxyindole(DHI)monomer,which may lead to the inherent compactπ-conjugation stacking microstructures and finally results in limited antioxidative capacities.To address this issue,we have strived to involve condensation polymerization during the melanin synthetic process,aiming to disrupt the compact stacking microstructures and improve the total antioxidative performance.The resulting melaninlike nanoparticles(NPs)indeed possessed less compact stackingπ-conjugation structures and decreased density,which further demonstrated enhanced antioxidative abilities compared with conventional melanin-like polymers such as poly-5,6-dihydroxyindole(Poly-DHI)and polydopamine(PDA).Their excellent free radical scavenging capability was further confirmed by the intracellular cell protection effects against reactive oxygen species(ROS)as well as in vivo therapy for acute diseases including acute kidney injury and acute liver injury.This work would promote future work toward new types of melanin-inspired nanomaterials with tunable and improved functions beyond nature.

STUDY ON THE CARDANOL-ALDEHYDE CONDENSATION POLYMER CONTAINING BORON-NITROGEN COORDINATE BOND

Cardanol-aldehyde condensation polymer containing boron-nitrogen coordinate bond (CFBN) has been synthesized and characterized by IR, XPS, HPLC and DTA-TG. Its properties were also investigated. The results show that the coating film of CFBN has excellent physico-mechanical properties, good anticorrosive properties and stable at high temperature. (Author abstract) 8 Refs.

Synthesis and Characterization of Poly (ether imide)s Containing Phthalazinone and Isopropyl Moieties

A novel poly(ether imide)s containing phthalazinone and isopropyl moieties derived from 2-(4-aminophenyl)-4-[4-(4-aminophenoxy)phenyl]-phthalazin-1-one and bisphenol-A diphthalic anhydride was synthesized by one-step solution condensation polymerization in nr-cresol. The polymer was characterized by FTIR, NMR, molecular weights, glass transition temperature, thermal degradation temperature and WAXD.

CROSSLINKED ORGANOSILOXANE HYBRID MATERIALS PREPARED BY CONDENSATION OF SILANOL AND MODIFIED SILICA: SYNTHESIS AND CHARACTERIZATION

Hybrid materials based on polymethylphenylsiloxane （PMPS） and organic functionalized silica were synthesized via condensation reaction between silanol and alkoxysilyl groups in the presence of quaternary ammonium hydroxide. The structure of prepared materials was investigated by FTIR and NMR, which indicate that the products have incorporated modified silica into the polymer matrix. The prepared hybrid materials show a satisfactory thermal resistance because the initial decomposition of typical product occurred at nearly 100 K higher than that of the pure polymer according to the thermogravimetric analysis （TGA） results. Differential thermogravimetric analysis （DTGA） data confirm that the thermal degradation of prepared hybrid materials comprises of two steps, of which the first one could be controlled by adjusting the content of silica particles and the ratio of surface groups on the particles. The coating films obtained from hybrid products exhibit good thermal mechanical properties. Therefore, the materials are hoped to be used for the application in thermal resistant coating.

SYNTHESIS AND CHARACTERIZATION OF NOVEL OPTICALLY ACTIVE POLY(AMIDE-IMIDE)S AND POLY(ESTER-IMIDE)S CONTAINING CALIX[4]ARENE AND AMINO ACID UNITS WITH BINDING ABILITY TOWARDS ALKALI METAL AND TOXIC HEAVY METAL CATIONS

A novel calix[4]arene derivative 2 with amino functional groups at the lower rim was first prepared via introduction of nitro functional groups and amination of the dinitro derivative of calix[4]arene. The optically active monomers were synthesized by dehydration of L-leucine （and L-isoleucine） and 3,3＇,4,4＇-benzophenonetetracarboxylic- 3,3＇,4,4＇-dianhydride （3） followed by reaction with thionyl chloride to form 5a and 5b. Two methods, polymerization under microwave irradiation and solution polymerization in CH2Cl2/TEA, were then employed to carry out the condensation polymerization of 2 with the optically active monomers 5a and 5b, respectively. The polymerization conditions affected the kind of resulting polymers, poly（amide-imide）s （PAIs） 6a and 6b and poly（ester-imide）s （PEIs） 6a＇ and 6b＇ were obtained selectively in good yields and moderate inherent viscosities. Sorption-extraction experiments were carried out using cram picrate extraction method and verified good binding ability of the resulting calixarene-based polymers towards silver, alkali metal and toxic heavy metal cations. Also thermogravimetric analysis indicated that the resulting PAIs and PEIs were thermally stable.