Synthesis and properties of new polyamides based on a hydroxyethyl cinnamide extended from 3,5‐diaminobenzoic acid

A series of new aromatic polyamides containing cinnamide pendent units were prepared from 2′‐(cinnamide)ethyl‐3,5‐diaminobenzoate and various aromatic dicarboxylic acids by the direct polycondensation reaction, with triphenyl phosphite and pyridine as condensing agents. The polyamides were characterized by ¹H NMR, IR, and UV spectroscopy, and gel permeation chromatography. Their thermal stability was studied by thermogravimetric analysis in air, and differential scanning calorimetry. These polymers were readily soluble in polar aprotic solvents and can be cast from their solutions in flexible and tough films. Glass transition temperatures (T_gs) of these polyamides were observed in the range of 225–245°C. Their inherent viscosities varied from 0.77 to 1.12 dL/g that corresponded to weight–average and number–average molecular weights of 39,000–72,700 and 18,800–29,000, respectively. These polymers can be photochemically crosslinked. The photochemical aspects were revealed by means of UV–vis and IR analyses onto thin films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2013–2020, 2007     

Microfluidic device for continuous magnetophoretic separation of white blood cells

This paper presents a microfluidic device for magnetophoretic separation of red blood cells from blood under continuous flow. The separation method consists of continuous flow of a blood sample (diluted in PBS) through a microfluidic channel which presents on the bottom “dots” of ferromagnetic layer. By applying a magnetic field perpendicular on the flowing direction, the ferromagnetic “dots” generate a gradient of magnetic field which amplifies the magnetic force. As a result, the red blood cells are captured on the bottom of the microfluidic channel while the rest of the blood is collected at the outlet. Experimental results show that an average of 95% of red blood cells is trapped in the device.     

Novel chalcone-based aromatic polyamides: synthesis,characterization, and properties

Two novel diacid-based monomers have been synthesized by anchoring a benzylideneacetophenone (chalcone) moiety through an amide or ester bridge at the fifth position of the isophthalic acid ring. Two series of new polyamides bearing chalcone side chains were prepared by direct polycondensation reaction of the aforementioned dicarboxylic acids and various aromatic diamines in N-methyl-2-pyrrolidinone, using triphenyl phosphite and pyridine as condensing agents. Their molecular structure and the basic properties were investigated by nuclear magnetic resonance, Fourier-transform IR and UV–vis spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction. The inherent viscosity, molecular weights measurements (by gel permeation chromatography), water uptake, and solubility tests completed the research study. Introduction of the rigid and bulky chalcone units into the polymer side chains improved remarkably the solubility of the aromatic polyamides, endowed them with an amorphous nature, good thermal stability, and photosensitivity. The resulting polymers were obtained in good yields, inherent viscosities varied between 0.49 and 0.86 dL/g, and their relative high molecular weights conferred them film-forming properties. They were soluble in amide-type polar solvents, such as N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. These polyamides had glass transition temperatures between 219 and 264 °C, and 10% weight loss temperatures in the range of 394–436 °C and around 50% residue at 700 °C in nitrogen atmosphere. The polyamides underwent a [2 + 2] photocycloaddition reaction upon UV light irradiation both in solution and film state in the absence of a photoinitiator or photosensitizer. The polymer films became insoluble in solvents as a result of the crosslinking .     

The Effect of Small Additions of Fe and Heavy Deformation on the Precipitation in an Al–1.1Mg–0.5Cu–0.3Si At. Pct Alloy

Metallurgical and Materials Transactions A - The effect of 0.03 and 0.08 at. pct Fe additions on the formation of secondary phases in an Al–1.1Mg–0.5Cu–0.3Si at. pct alloy was...     

Synthesis and characterization of some polyamides incorporating modified isophthalic acid units

Some polyamides with side chains were prepared using a direct polycondensation reaction between carboxyl groups from O‐cinnamoyl‐5‐hydroxyisophthalic acid and N‐cinnamoyl‐5‐aminoisophthalic acid and various diisocyanates in the presence of 4‐dimethylaminopyridine, as catalyst, without use of condensing agents. The polymers were characterized by elemental analysis, viscosimetry, spectroscopic and thermal measurements. © 2002 Society of Chemical Industry     

Polymeric N‐allyl vinylpyridinium salts as addition–fragmentation type initiators for cationic polymerization

Polymeric allyl pyridinium salts were synthesized from styrene and 4‐vinyl pyridine copolymers by quaternization and counteranion exchange reactions. The initiation capability of these copolymers, in conjunction with a photochemical free radical source such as benzoin, via an addition –fragmentation mechanism in the cationic polymerization of cyclohexene oxide is investigated. © 2001 Society of Chemical Industry     

Clustering and Vacancy Behavior in High- and Low-Solute Al-Mg-Si Alloys

The precipitate microstructure and vacancy distribution in Al-Mg-Si alloys with different amounts of solute and different heat treatments were investigated by transmission electron microscopy and muon spin relaxation measurements. A high amount of vacancies is normally present in Al-Mg-Si alloys as these bind to atomic clusters. We observe these vacancies to leave the material not before over-aging at very high temperatures such as 623 K (350 °C), meaning that vacancies do not bind to incoherent over-aged precipitates. For samples only stored at room temperature after solution heat treatment, a reduction of muon trapping was found at a temperature of 140 K (?133 °C) when reducing the amount of solute in the alloy. This might be connected to a lower number density of Cluster (1), which contrary to Cluster (2) do not nucleate precipitates upon further aging of the material.     

Pyrene functionalized side chain alanine and histidine containing copolyacrylates prepared by free radical copolymerization

An optically active copolyacrylate, poly(N‐acryloyl‐L‐alanine‐co‐N‐acryloyl‐L‐histidine), is prepared by classical radical copolymerization of N‐acryloyl‐L‐alanine and N‐acryloyl‐L‐histidine, and further chemically modified with 1‐pyrene‐methanol. The structures of the synthesized compounds are confirmed by spectral analysis (FTIR, ¹H/¹³C‐NMR, UV, fluorescence spectroscopy), thermal methods, and molecular weight measurements. Also, their optical activity is studied using circular dichroism (CD) spectroscopy and optical rotation measurements. The specific rotation values reveal that the direction of rotation of the parent copolymer is dictated by the monomer containing L‐alanine. CD data suggest negative and positive Cotton effects regarding the monomers with amino acids. In the case of the unmodified copolymer it is noted the changes of ellipticity values with increasing pH while the random‐coil conformation is preserved, which makes it suitable as a pH‐responsive system. Photochemical and photophysical investigations reveal that the pyrene‐functionalized chiroptical copolyacrylate can be used as a fluorescent chemosensor for the detection of nitro‐derivatives in organic media. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44457.