A new and one-pot protocol for mass-producable synthesis of the poly(ethylene oxide propylphosphonamidate) (PEOPPA) hydrogel bearing multi-amine and multi-amino groups with excellent swellability and flexibility has been described. The structural characterization of the formed gel was well analyzed by infrared, solid state 31 P-NMR and X-ray photoelectron spectroscopies, and scanning electron microscopy. Rheological properties and swellability are carefully measured and discussed as well. The PEOPPA hydrogels have been used as a template and reducing agent for the synthesis of a series of noble metal nanoparticles (MNPs) (Au, Ag, Pd, Pt and Ru NPs) in the absence of any other reducing agents and stabilizers. In situ formed MNPs were uniformly impregnated inside the hydrogel without secession, efficiently avoiding aggregation-induced loss of catalytic activity. The MNP-impregnated hydrogels were employed for the reduction of various nitroaromatics in the presence of sodium borohydride in aqueous media, showing very high catalytic activity. These systems exhibit excellent recyclability in an easy way. The catalytic activity in enhancing the conversion rate increases in accordance with a series: PEOPPA hydrogel supported (HS) Ru NP , HS Ag NP , HS Au NP , HS Pt NP , HS Pd NP. The reaction rate constants at 10, 30 and 50 uC and the activation energies with other activation parameters were estimated. The activation energies for the reduction of 2,6-dinitrophenol, 2,4-dinitrophenol, 4-nitrophenol and 2,4,6-trinitrophenol catalyzed by the HS Au NP are 35.13, 29.08, 22.03 and 32.01 kJ mol 21 , respectively.
This paper reviews the recent research and development of hyperbranched polymers (HPs) and dendrimers, and their use as templates for organic-inorganic hybrid nanomaterials. Hyperbranched polymers (HPs) are highly branched macromolecules with three-dimensional globular structures featuring unique properties such as low viscosity, high solubility, and a large number of terminal functional groups compared to their linear analogs. They are easily prepared by (1) condensation polymerization, (2) self-condensing vinyl copolymerization (SCVCP), and (3) ring-opening multibranch polymerization methods. Organic-inorganic hybrid nanomaterials are synthesized by a template approach using HPs/dendrimers. Monometallic, bimetallic (alloy and core/shell), semiconductor, and metal oxide nanoparticles have been prepared by this route. The dendrimer component of these composites serves not only as a template for preparing the nanoparticles but also as a stabilizer for the nanoparticles.
A series of degradable, water-swellable PEGs are prepared using crosslinking between primary amines of N,N',N″-tris(2-aminoethyl)phosphoric triamide (TAEPT) and diglycidyl ether of epichlorohydrin-modified PEGs (EMPs). In the crosslinking process, the glycidyl ether is mainly consumed by the -NH2 of TAEPT and the hydroxyl generated from the opened glycidyl ethers (C-OH), producing degradable phosphonyl-amide frameworks as crosslinked points, and ether bonds as short branches, respectively. Studies on anticancer drug entrapment, chemoimmunotherapy agent delivery, degradation, and biological cytotoxicity in vitro suggest that the generated hydrogels have great potential as biomaterials in biomedical applications.
A series of oleamide derivatives, (C(18)H(34)NO)(2)(CH(2))(n) [n = 2 (1a), 3 (1b), 4 (1c), or 6 (1d); C(18)H(34)NO = oleic amide fragment] and (C(18)H(34)NO)(CH(2))(6)NH(2) (2), have been synthesized and their self-assembly is investigated in ethanol/water media. Self-assembly of 1a and 1b in ethanol/water (1/0.1 v/v) solution (5 mg mL(-1)) yields microspheres (MSs) with the average diameter ∼10 μm via a gradual temperature reduction and solvent volatilization process. Under the same self-assembly conditions, microrods (average diameter ∼6 μm and several tens of micrometers in length), micronecklace-like, and shape-irregular microparticles are formed from the self-assembly of 1c, 1d, and 2, respectively. The kinetics of evolution for their self-assemblies by dynamic light scattering technique and in situ observation by optical microscopy reveals that the microstructures formation is from a well-behaved aggregation of nanoscale micelles induced by solvent volatilization. The FT-IR and temperature-dependent (1)H-NMR spectra demonstrate the hydrogen bonding force and π-π stacking, which drove the self-assembly of all oleamide derivatives in ethanol/water. Among the fabricated microstructures, the MSs from 1a exhibit the best dispersity, which thus have been used as a scaffold for the in vitro release of doxorubicin. The results demonstrate a pH-sensitive release process, enhanced release specifically at low pH 5.2.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.