Condensation Polymerization Process Research Articles

Construction of Amino‐Functionalized Molecularly Imprinted Silica Particles for (±)‐Ofloxacin Chiral Separation

AbstractTo enantioselectively separate a (±)‐ofloxacin (OFX) racemic mixture, we describe the production and successful use of an S‐ofloxacin (S‐OFX) enantio‐selective sorbent with amino functional groups. An amide derivative was first synthesized by reacting the S‐OFX enantiomer with 3‐aminopropyltriethoxysilane (S‐OFX‐Si‐NH2). The generated S‐OFX‐Si‐NH2 derivative was then mixed with tetraethoxysilane (TEOS) and put through a base‐catalyzed sol‐gel condensation polymerization process to insert the S‐OFX enantiomeric species into the cross‐linked material. To facilitate recombination involving S‐OFX, an enantioselective gap is created by alkaline hydrolysis followed by acidification, freeing the S‐OFX from the crosslinked matrix and filling the resulting gaps with cationic ions compatible with the S‐OFX. Our chemical transformations of the monomeric precursor and the ensuing S‐OFX molecularly imprinted material (S‐OFX‐Sil) were confirmed by elemental analysis, nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (FTIR). In addition, scanning electron microscopy images of the sorbent surface were employed to comprehend the morphological adjustments. Both the first loading run (60 % ee of R‐OFX) and the second elution run (83 % ee of S‐OFX) using the manufactured adsorbent particles showed promising separation results.

Molecular alignment induced high thermal conductivity in amorphous/ low crystalline polyimide fibers

It is of considerable scientific and technological importance to enhance the thermal conductivity (k) of polymers for the application in thermal management. In this work, we study the thermal transport in amorphous/low-crystalized polyimide (PI) composite fibers (crystallinity lower than 2%-10%) by using the transient electro-thermal (TET) technique and the steady-state electro-thermal (SET) technique from 320 K to 7 K. It is found that the amorphous/low-crystalized PI fibers can achieve a high k (2.13 W/m K) due to oriented chain alignment and inter-chain hydrogen bonds from the condensation polymerization, wet-spinning and low-ratio thermal drawing process. By using the thermal reffusivity (Θ) model, the phonon propagation in PI fibers is investigated. The structural domain size (SDZ) of the amorphous/low-crystalized PI fibers is determined based on the residual Θ at 0 K limit, which is calculated to be 3.85 nm and 9 nm for the undrawn and post-drawn PI fiber, respectively. The SDZ value is close to the radius of gyration (Rg) instead of the atomic scale characteristic length of PI. This result indicates that for amorphous/low crystalized PI fibers with hydrogen bonds, the Rg could have played a more important role in determining k.

Construction of CL‐20 Surface Layer with Different Wetting Properties and its Effect on Slurry Rheological Behavior and Mechanical Sensitivities

AbstractTo have a deep understanding of the effects of surface wettability on the mechanical sensitivity and rheological characteristics of PBX slurry, CL‐20 particles with hydrophilic property was prepared through a polymerization process of dopamine, and CL‐20 particles with hydrophobic property were prepared through a condensation polymerization process of hexadecyltrimethoxylsilane. The morphology, surface element content and surface wettability of CL‐20 crystals before and after modification were characterized by scanning electronic microscope (SEM), X‐ray photoelectron spectroscopy (XPS), and contact angle test. The rheological characteristics of CL‐20 based PBX slurry showed that the interaction between explosive particles and binder was changed with different surface wettability of CL‐20. The weaker interaction between CL‐20@hydrophobic and binder lead to weaker solid‐liquid friction, resulted in lower apparent viscosities of CL‐20@hydrophobic based PBX slurry at high shear rate. The mechanical sensitivity of wax coated CL‐20 with different surface wettability was tested. CL‐20@hydrophobic‐wax exhibited better mechanical stability compared to CL‐20‐wax and CL‐20@hydrophilic‐wax, probably owning to the weaker interaction between CL‐20@hydrophobic surface and wax.

Biosorption of Chromium from Textile Wastewater Using Mimosa pudica Tannin Gel

<p>The heavy metal content is very dangerous because it can pollute the environment. One of the heavy metals waste commonly found in the textile industry is chromium (Cr). <em>Mimosa pudica</em> is a weed plant and its availability is very abundant. However, it also contains tannin which can be developed into tannin gel biosorbent to adsorption heavy metal content in the wastewater. The purpose of this research is to study <em>Mimosa pudica</em> tannin as a Cr biosorbent from textile wastewater. There are two steps to synthesis tannin gel biosorbent. They are the tannin extraction and the condensation polymerization process. Tannin is easily soluble in water so the condensation polymerization process is needed to make it insoluble in water. The extraction of <em>Mimosa pudica </em>tannin was done using water solvent. The condensation polymerization process was done by the reaction of tannin extract and formaldehyde. The Cr content of textile industry wastewater in the Pasar Kliwon, Surakarta was 4 ppm. The results of the biosorption of Cr heavy metal using <em>Mimosa pudica</em> tannin gel showed that the remaining Cr heavy metal was 0.7098 ppm. It was already below the threshold which was 1 ppm.</p><p> </p><p><strong>Keywords:</strong> biosorption, condensation polymerization, extraction, <em>Mimosa pudica</em>, tannin gel</p>

Synthesis, characterization, thermal stability and kinetics of thermal degradation of novel polymers based-s-triazine Schiff base

The present work represents the synthesis of five new s-triazine based Schiff base polymers via condensation polymerization process between bishydrazino-s-triazine derivatives and terephtaldehyde. The prepared polymers were characterized by different techniques (FTIR, UV-Vis, TGA, XRD and DSC). The new polymers showed good thermal properties and good values for the Limited Oxygen Indexed (LOI) 22.74, 27.36, 30.52, 24.38, 21.39 for polymers 5a-e; TP-DHBT, TP-DHMBT, TP-DHMT, TP-DHPT, and TP-DHMeT, respectively. Accordingly, these types of polymers could be classified as flame-retardant and self-extinguishing polymers. The Tg values of the polymers 5a-e varied in the range from 191.4 to 241.1. The effect of substituent in the triazine ring has great impact on the properties of the polymers 5a-e as observed from the DSC and XRD results. Moreover, the thermal degradation kinetics of two selected polymers with higher thermal stability (5b and 5c) from the prepared series was studied using the method of Friedman. The behavior of activation energy is found to be highly dependent on the polymer molecular structure.

Quantum Dots as Promising Theranostic Tools Against Amyloidosis: A Review.

Amyloids are highly ordered beta sheet rich stable protein aggregates, which have been found to play a significant role in the onset of several degenerative diseases such as Alzheimer's disease, Huntington's disease, Parkinson's disease, Type II diabetes mellitus and so on. Aggregation of proteins leading to amyloid fibril formation via intermediate(s), is thought to be a nucleated condensation polymerization process associated with many pathological conditions. There has been extensive research to identify inhibitors of these disease oriented aggregation processes. In recent times, quantum dots, with their unique physico-chemical properties have grabbed the attention of scientific community due to its applications in medical sciences. Quantum dots are nano-particles usually made of semiconductor materials which emit fluorescence upon radiation. The wavelength of fluorescence emission varies with changes in size of quantum dots. Several studies have reported significant inhibitory effects of these quantum dots towards amyloidogenesis, thereby presenting themselves as promising candidates against amyloidosis. Further, studies have also revealed amyloid detection capacity of quantum dots with sensitivity and specificity better than conventional probes. In the current review, we will discuss the various effects of quantum dots on protein aggregation pathways, their mechanism of actions and their potentials as effective therapeutics against amyloidosis.

Concentration Insensitive Supramolecular Polymerization Enabled by Kinetically Interlocking Multiple-Units Strategy

Concentration Insensitive Supramolecular Polymerization Enabled by Kinetically Interlocking Multiple-Units Strategy

Review on Evaluation of properties of carbon phenolic composite structure using gas chromatography for analysis of thermal performance

Carbon-phenolic composites are meant for heat protection of the aerospace structures like aircraft skins, nozzles and heat shields during the aerodynamics loading conditions. Phenolic resin matrix composites are used as ablative liners to resist thermal and erosive environment. The manufacturing process of Carbon phenolic composite structure require curing. During the curing of phenolic matrix components, methylol-phenol and water are evolved as by-products due to condensation polymerization process either in the presence of heat/hardeners. In order to obtain void free component, it is required to remove the by-products by curing the component simultaneously under heat, vacuum and pressure. Therefore autoclave-curing process is the most suitable process for curing of the phenolic resin.In this review paper, On-line cure monitoring of Carbon-Phenolic Composite Structures by Gas chromatography for wet lay ups and prepreg based components has been studied. Heat of reaction and the volume of chemical species evolved under aerodynamic heating are measured by Pyrolysis gas chromatography (Py-GC) and thermo gravimetry (TG), which will be used as inputs for thermal evaluation of the structure. Properties of carbon Phenolic is estimated through this study. USIM software used to visualize properties of surrounding air and carbon phenolic structure.

Swelling behavior and chemical stability of chitosan/nanocellulose biocomposites

We investigated the chemical stability and swelling behaviour of synthesized biocomposites with varying concentrations of oil palm frond (OPF) nanocellulose and chitosan (Cs) for biomedical applications. Nanocellulose were extracted via acid hydrolysis method from OPFs and commercialized (COM) cellulose for comparative analysis. Condensation polymerization process was implemented to incorporate the nanocellulose and N, N’‐Methylenebisacrylamide (MBA) crosslinker into the Cs. Flory‐Huggin model was used to test their swelling behavior. Biocomposites in wet condition was observed through a variable pressure scanning electron microscopy (VP‐SEM). Results showed that increasing the amount of nanocellulose on the biocomposites can reduce the swelling of the Cs, and it is significantly reduced (up to 420% at pH 4, up to 576% at pH 7, up to 305% at pH 10) with the use of OPF nanocellulose. Moreover, adding OPF nanocellulose to Cs has improved its stability in acidic medium, basic medium, aprotic solvent, polar solvent, non‐polar solvent up to 90, 23, 23, 18, 22%, respectively. The swelling resistance and chemical stability of Cs biocomposites with OPF nanocellulose were better than using COM nanocellulose. POLYM. COMPOS., 39:E561–E572, 2018. © 2018 Society of Plastics Engineers

Effects of environmental aging on physical properties of aromatic thermosetting copolyester matrix neat and nanocomposite foams

This paper focuses on the effects of cyclic water immersion and salt spray aging tests on the physical properties of aromatic thermosetting copolyester (ATSP) matrix. Neat and graphene nanoplatelet (GNP) incorporated nanocomposite ATSP foam morphologies are employed to have enhanced surface areas exposed to the surrounding aqueous media, via porous configurations, which deliberately aggravate the extent of the aging on the matrix. The ATSP foams are fabricated through a thermal condensation polymerization process. Upon exposures to the periodic aging conditions, ATSP demonstrates an adsorption-regulated mass uptake mechanism. Contact angle measurements reveal GNP-neutral and hydrophobic characteristics for the ATSP matrix. Microstructural imaging exhibits no substantial physical degeneration in the matrix caused by the accelerated aging conditions. Glass transition temperatures of both neat and nanofiller incorporated ATSP forms display only marginal decreases stemmed from small volumes in the matrix occupied through the hygroscopic swelling. Thermal degradation stability of the ATSP morphology is effectively preserved following the aging processes. Compressive mechanical strengths of the foams lie within the regime of their virgin (not exposed to the aging conditions) counterparts yet show slight reductions. The ATSP matrix demonstrates an outstanding aging resistance to the subjected environments which can potentially address high-performance requirements in cutting-edge industrial applications.

Fragmentable Polycationic Materials Based on Anchimeric Assistance

A new family of modular, fragmentable oligo- and polycations has been developed based on the reactions of 9-thiabicyclo[3.3.1]dichloride and related compounds with substituted dipyridyl nucleophiles by an anchimeric assistance mechanism. Each bond-forming event in this condensation polymerization process generates a positive charge in the main chain. Product lengths were found to be dependent on the reactivity of the electrophile, which was tunable by changing the nature of the leaving group β to sulfur. The monomers were easily synthesized, and the resulting readily available polymers were found to be highly efficient binders of nucleic acid. They exhibited properties of cytotoxicity and DNA transfection expected of such polycationic materials, but with interesting structure–activity differences that remain to be explored. The polycations decomposed by hydrolysis at rates dependent on the leaving group ability of the pyridyl unit, which correlated roughly with the pKa of its conjugate acid. Polymer decom...

Polypyrrole–vinyl aniline modified cyclohexanone formaldehyde resin copolymers: a comparative study of the resin preparation

ABSTRACTIn this study, the synthesis of polypyrrole‐b‐vinyl aniline modified cyclohexanone formaldehyde resin (PPy‐b‐CFVAnR) block copolymers by a combination of condensation polymerization and chemical oxidative polymerization processes was examined. First, a cyclohexanone formaldehyde resin containing vinyl aniline units [4‐ vinyl aniline modified cyclşohexanone formaldehyde resin (CFVAnR)] was prepared by a direct condensation reaction of 4‐vinyl aniline and cyclohexanone with formaldehyde in an in situ modification reaction. CFVAnR and pyrrole (Py) were then used with a conventional method of in situ chemical oxidative polymerization. The reactions were carried out with heat‐activated potassium persulfate salt in the presence of p‐toluene sulfonic acid in a dimethyl sulfoxide–water binary solvent system; this led to the formation of desired block copolymers. The effects of the oxidant–monomer molar ratio, dopant existence, addition order of the reactants, and reaction temperature on the yield, conductivity, and morphology of the resulting products were investigated. PPy‐b‐CFVAnR copolymers prepared with a resin‐to‐Py molar ratio of 1:40 showed conductivity in the range 3.7 × 10−1 to 3.8 × 10−2 S/cm. Oxidant‐to‐Py molar ratios of 0.5 and 1.0 were proposed to be the optimum stoichiometries for higher conductivity and yield, respectively, of the copolymer. The morphology of the copolymer (PPy‐b‐CFVAnR) was investigated with environmental scanning electron microscopy analyses. The results indicate that the surface of the copolymer was composed of well‐distributed nanospheres with average particle diameters of 60–85 nm. Also, the synthesized PPy‐b‐CFVAnR had a higher thermal stability than the pure CFVAnR. The chemical composition and structure of the PPy‐b‐CFVAnR copolymers were characterized by Fourier transform infrared spectroscopy and measurement. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42841.

Synthesis and Luminescent Properties of Tetrafluorophenyl Containing Poly(p-phenylenevinylene) Derivatives

To investigate the effect of fluoro groups substitution on poly(p-phenylenevinylene) derivatives, poly(2,3,5,6- tetrafluoro-p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCTF-PPV, and poly[2,3,5,6-tetrafluoro-p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], PMTF-PPV, were synthesized by the well-known Wittig condensation polymerization process. To compare the influences of fluoro groups, no fluoro groups containing model polymers, poly(p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCPPPV and poly[p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], p-PMEH-PPV, were also synthesized. The resulting polymers were completely soluble in common organic solvents and exhibited good thermal stability up to 300℃. The polymers showed UV-visible absorbance and photoluminescence (PL) in the ranges of 259~452 nm and 500~580 nm, respectively. The tetrafluorophenyl containing PCTF-PPV and PMTF-PPV showed relatively red-shifted PL peaks at 521 nm and 580 nm, respectively, compared to that of non-fluoro groups containing polymers (PCP-PPV: 500 nm and p-PMEH-PPV: 539 nm). The single-layer light-emitting diode was fabricated in a configuration of ITO/polymer/Al. Electroluminescene (EL) emissions of PCP-PPV, PCTF-PPV, p-PMEH-PPV and PMTF-PPV were shown at 507, 524, 556, and 616 nm, respectively.

Effect of molecular structure of aniline–formaldehyde copolymers on corrosion inhibition of mild steel in hydrochloric acid solution

Aniline–formaldehyde copolymers with different molecular structures have been prepared and investigated for the purpose of corrosion control of mild steel in hydrochloric acid. The copolymers were synthesized by a condensation polymerization process with different ratios of aniline to formaldehyde in acidic precursor solutions. The corrosion inhibition efficiency of as-synthesized copolymers for Q235 mild steel was investigated in 1.0molL−1 hydrochloric acid solution by weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy, respectively. All the results demonstrate that as-prepared aniline–formaldehyde copolymers are efficient mixed-type corrosion inhibitors for mild steels in hydrochloric acid. The corrosion inhibition mechanism is discussed in terms of the role of molecular structure on adsorption of the copolymers onto the steel surface in acid solution.

Supramolecular Chemistry in the Formation of Self-Assembled Nanostructures from a High-Molecular-Weight Rod-Coil Block Copolymer.

The self-assembled nanostructures of a high-molecular-weight rod-coil block copolymer, poly(styrene-block-(2,5-bis[4-methoxyphenyl]oxycarbonyl)styrene) (PS-b-PMPCS), in p-xylene are studied. The cylindrical micelles, long segmental cylindrical micelle associates, spherical micelles, and spherical micelle associates are observed with increased copolymer concentration. The high molecular weight of PS leads to the entanglement between PS chains from different micelles, which is the force for supramolecular interactions. Short cylindrical micelles are connected end-to-end via this supramolecular chemistry to form long segmental cylindrical micelle associates, analogue to the condensation polymerization process, with direction and saturation. On the other hand, spherical micelles assemble via supramolecular chemistry to form spherical micelle associates, yet without any direction due to their isotropic properties.

Synthesize Multiblock Copolymers via Complex Formations between β-Cyclodextrin and Adamantane Groups Terminated at Diblock Copolymer Ends: A Brownian Dynamics Simulation Study

Coarse-grained models for β-cyclodextrin (β-CD) and adamantane (ADA) are proposed by fitting to their experimental host-guest complex equilibrium constant in solution. By using Brownian dynamics simulations, we suggest a simple supramolecular route for synthesizing multiblock copolymers (MBCs) via forming complexes between β-CD and ADA groups terminated at the chain ends of diblock copolymers (DBCs). The chain length distribution of the resulted MBC is found to follow the statistics of Flory formula for typical linear condensation polymerization process. Therefore, the proposed supramolecular route can be viewed as a novel linear condensation polymerization process with DBCs as reactive monomers. Due to the complex formations between head and tail (β-CD and ADA), ring-shaped MBCs are also observed in our simulations, which will reduce the yield of the MBC. Because we are using a generic model for DBC, the proposed route of building MBCs are applicable for all synthetic DBCs with two ends terminated by either β-CD or ADA groups.

Self-repairing vanadium–zirconium composite conversion coating for aluminum alloys

In this paper, new self-repairing vanadium–zirconium composite conversion coating was prepared and investigated by Electrochemical impedance spectra (EIS), Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. EIS results showed that V–Zr conversion coating with hydrogen peroxide modified (VZO) revealed an increasing corrosion resistance in corrosive media which meant a certain self-repairing effect. SEM comparison photos also disclosed that VZO treated with scratches was gradually ameliorated from the initial cracked configuration to fewer cracks and more fillers through an immersion of 3.5% NaCl solution. XPS results demonstrated that the content of vanadium on VZO increased and zirconium declined when immersed in the corrosive solution. This explained further that the self-repairing ability could be related to vanadium. From the above results, we inferred possible structures of VZO and proposed that self-repairing effect was achieved through a hydrolysis condensation polymerization process of vanadate in the localized corrosion area.

Exploring suitable oligoamines for phantom ring-closing condensation polymerization with guanidine hydrochloride

Different model compounds were applied in step-growth condensation reactions with guanidine hydrochloride in order to explore the scope of tri- and oligoamine applicability for phantom ring-closing condensation polymerization processes. The selective formation of five-membered rings was proven by APCI mass spectrometry, different one- and two-dimensional homo- and heteronuclear coupling NMR techniques and investigated via quantum chemical calculations. Furthermore the possibility of ring-closing reactions among guanidine hydrochloride and merely secondary amines was precluded. The obtained oligomers were exposed to antibacterial tests and exhibited a moderate activity towards Escherichia coli.

Photochemically prepared polysulfone/poly(ethylene glycol) amphiphilic networks and their biomolecule adsorption properties

Polysulfone/poly(ethylene glycol) amphiphilic networks were prepared via in situ photo-induced free radical crosslinking polymerization. First, the hydrophobic polysulfone diacrylate (PSU-DA) oligomer was synthesized by condensation polymerization and subsequent esterification processes. Then, the obtained oligomer was co-crosslinked with the hydrophilic poly(ethylene glycol) diacrylate (PEG-DA) or poly(ethylene glycol) methyl ether acrylate (PEG-MA) at different feed ratios. In the case of PEG-MA, the resulting network possessed dangling pendant hydrophilic chains on the crosslinked surface. The structure and the morphology of the membranes were characterized by attenuated total reflection infrared spectroscopy (ATR-IR) and scanning electron microscopy (SEM). The enhancement of surface hydrophilicity was investigated by water contact angle measurements. The biomolecule adsorption properties of these networks were also studied. The biomolecules easily adsorbed on the surface of the hydrophobic polysulfone networks whereas dangling hydrophilic chains on the surface prevented the adsorption of the biomolecules.

Study on the Chemical Modification of Titanium-Doped Silicone Using Hydroxyl-Terminated Saturated Polyester

In this paper, a kind of titanium-doped silicone prepolymer(TDS) was modified by hydroxyl-terminated saturated polyester (HTSP) by condensation polymerization. By Fourier Transform Infrared Spectroscopy (FTIR) the reaction of ethoxy groups of the TDS prepolymer with hydroxyl groups of the HTSP during condensation polymerization process was confirmed. The resins were cured with blocked polymeric isocyanate. The influence of the HTSP content on the properties of the modified resins such as thermal stability, corrosion resistance, as well as mechanical and other properties, were discussed in detail. The results showed that the properties of the resins were improved greatly after modification, and the optimal mass ratio of TDS to HTSP in the modified resins was 1:1. Thermogravimetry analysis (TGA) studies indicated that the weight loss of this sample（wTDS : wHTSP =1:1） was not obviously below 400°Cand the impedance value of this coating was significantly higher than that of the others.