Polycondensation Process Research Articles

A comprehensive review on microbial degradation of plastic waste

Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed. Plastics have become an important part of modern life and are used in different sectors of applications like packaging, building materials, consumer products and much more. Each year about 100 million tons of plastics are produced worldwide. Degradation is defined as reduction in the molecular weight of the polymer. The Degradation types are (a). Chain end degradation/de-polymerization (b).Random degradation/reverse of the poly condensation process. Biodegradation is defined as reduction in the molecular weight by naturally occurring microorganisms such as bacteria, fungi, and actinomycetes. That is involved in the degradation of both natural and synthetic plastics.

Solid‐state polymerization process for the preparation of poly(cyclohexane‐1,4‐dimethylene cyclohexane‐1,4‐dicarboxylate) polymers with high melting temperature and crystallinity

Poly(cyclohexane‐1,4‐dimethylene cyclohexane‐1,4‐dicarboxylate) has been prepared by solid‐state polymerization using 1,4‐cyclohexanedicarboxylic acid or its di‐methylester and 1,4‐cyclohexanedimethanol as monomers. The process consists in a first step in which a prepolymer with high crystallinity is prepared by melt polycondensation and then submitted to solid‐state polymerization (SSP) at a temperature below the melting temperature of the polymer. The use of the solid state process permits to minimize the isomerization from the trans to the cis form in the polymer chain and therefore a polyester with higher crystallinity and melting temperature, compared to those synthesized by the traditional polycondensation routes, can be obtained. For this reason, the SSP process allows to obtain materials with thermo‐mechanical properties that cannot be achieved using the standard polycondensation method. Moreover, the process does not involve a complex multi‐step temperature ramp as in the case of the polycondensation process. POLYM. ENG. SCI., 58:1981–1986, 2018. © 2017 Society of Plastics Engineers

Optical properties of phenylene–thiophene-based polyazomethine thin films

Thin films of new aromatic polyazomethines, containing thiophene rings in their polymer chain structures, were obtained by the chemical vapor deposition method, via a polycondensation process from thiophene-2,5-dicarbaldehyde and one of four different aromatic diamines, as initial monomers. Spectroscopic ellipsometry, attenuated total reflectance mode of Fourier transform infrared spectroscopy, atomic force microscopy, and wide-angle X-ray diffraction techniques have been used to characterize these films. However, the optical transmission and reflectivity measurements, within the wide spectral UV-Vis-NIR range (0.5–6.2 eV), were the basic method of presented investigations. On the basis of optical measurements, the absorption coefficient spectra of these thin films were obtained and the absorption edge parameters, that is, the energy gap ( EG) and Urbach energy ( EU), were calculated in a way typical for amorphous semiconductors. These parameters allowed one to evaluate the length of conjugation and the extension of localized, defect states inside the energy gap, respectively, and to discuss the electronic transitions, being dependent on the chemical structure and conformation of polymer chains. Optical properties of these new phenylene–thiophene-based polyazomethine films were compared with their entirely phenylene counterparts. In general, the energy gaps of investigated films were clearly smaller (about 0.2 eV) than those of their phenylene counterparts, confirming that the presence of thiophene rings in polyazomethine structures improves conjugation.

An eco-friendly approach for toughening of polylactic acid from itaconic acid based elastomer

Sustainable and biocompatible novel lactic acid based bioelastomer (LBPE) was synthesized by polycondensation process which has been confirmed by FTIR and 1H NMR. Owing to the resemblances in the lactate structures of polylactic acid (PLA) and LBPE, the synthesized LBPE bioelastomers can act as an excellent PLA toughener in presence of free radical initiator dicumyl peroxide (DCP). The mechanical, morphological and thermal were investigated. Chemical crosslinks endow the LBPE with relatively high elasticity and environmental stability which ultimately enhances the mechanical properties of PLA matrix.

The degradability and thermal properties of chiral polyamide-imides synthesized from several l-amino acids: Side group effects

A series of chiral optically active monomers were prepared from l-amino acids with different structures. These monomers were polymerized to chiral polyamide-imides (PAIs) via an eco-friendly direct polycondensation process. The glass transition temperature (Tg) values were obtained by differential scanning calorimetry (DSC), and showed that the rigid and bulk effect of the substituents will co-affect the Tg values of the polymers. Their degradability were studied via soil degradation experiments, and the variations of water contact angles, molecular weights, structure and appearance during degradation were characterized by contact angle tester, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) respectively. The results revealed that the damages of polymer chains started with the amide bonds, and then proceed to the imide rings. With degradation, PAI films' hydrophilicity raised, and when introduced amino acids with longer carbon chain or bulky ring into the polymers' backbone, their degradability decreased.

Cyclic polylactides via simultaneous ring‐opening polymerization and polycondensation catalyzed by dibutyltin mercaptides

ABSTRACTl‐Lactide is polymerized in bulk at 160 °C either with dibutyltin bis(benzylmercaptide) (SnSBzl), dibutyltin bis(benzothiazole 2‐mercaptide) (SnMBT), or with dibutyltin bis(pentafluorothiophenolate) (SnSPF) as catalysts. SnSBzl yields linear polylactides having benzylthio‐ester end groups in addition to cyclic polylactides, whereas SnMBT and SnSPF mainly or exclusively yield cyclic polylactides. This finding, together with model reactions, indicates that the SnS catalysts promote a combined ring‐opening polymerization and polycondensation process including end‐to‐end cyclization. SnMBT caused slight racemization (3%–5%), when used at 160 °C. With SnSPF optically pure cyclic poly(l‐lactide)s with high‐molecular weights can be prepared at 160 °C. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3767–3775

Green solvent-based sol–gel synthesis of monticellite nanoparticles: a rapid and efficient approach

In this research, high-pure monticellite ceramic (CaMgSiO4) nanoparticles were synthesized via a novel sol–gel method using ethanol and chloride ions for the acceleration of polycondensation process. The gel obtained from metal alkoxide and metal salts precursors dried at 100°C; then, the dried-gel calcined at different temperatures to monitor the structural development of the final samples. The effect of various heat-treatment temperatures on the x-ray diffraction patterns, followed by the calculations from scherrer’s equation, showed that the grain size of the synthesized samples at 1200°C was around 28 nm. Based on dynamic light scattering spectroscopy, the size of most of the particles was ~85 nm. Williamson–Hall formula was also used to calculate the lattice strain of the samples. According to the results, by changing the heat-treatment temperature, lattice strain/stress, lattice parameters and grain size have meaningfully changed. The proposed synthesis method showed superior advantages in comparison with the other conventional techniques presented in the literature, which is relatively faster at lower temperatures. The synthesized high-pure monticellite nanoparticles could be applied in different biomedical engineering applications in which the purity and structural properties are of importance, such as dental, bone tissue engineering, coatings on biomedical implants, surgery hemostasis and inducing osteogenesis in vivo applications.

Group IVB Metallocene Polyesters Containing Camphoric Acid and Preliminary Cancer Cell Activity

Polyesters were formed from the reaction of the salt of camphoric acid and Group IVB metallocene dichlorides employing the interfacial polycondensation process. The polyesters were formed in good yields with moderate chain lengths. FTIR shows bands characteristic of the presence of both reactants with new bands characteristic of the formation of the M-O and M-O(CO) linkage present. The polymers largely exist in a bridging geometry of the carbonyl-groups about the metal atom. NMR shows the presence of bands derived from both reactants. MALDI MS shows ion fragments to three units for the polymers with isotopic abundances characteristic of the presence of metal atoms in the ion fragment clusters. All of the polymers exhibit good ability to inhibit all of the tested cancer cell lines but the zironocene and hafnocene polymers exhibit especially good inhibition of the tested cancer cell lines that included two pancreatic cancer cell lines. They represent a potential new group of anticancer drugs.Polyesters were formed from camphoric acid and Group IVB metallocene dichlorides employing the interfacial polycondensation process. IR, NMR and MLADI MS results are consistent with the proposed structure. Polymers exhibit outstanding ability to inhibit the tested cancer cell lines including two pancreatic cancer cell lines. They represent a potential new group of anticancer drugs.

Synthesis and optoelectronic properties of new polyarylates with 2-naphthyldiphenylamine units

Herein, five kinds of soluble electrochromic polyarylates were synthesized from the reaction of N,N'-bis(4-carboxyphenyl)-N,N'-di-2-naphthyl-1,4-phenylenediamine with five bisphenols via direct polycondensation process, respectively. These new materials showed no significant decomposition below 400°C in nitrogen atmosphere. The maximum UV–vis absorption bands of these polyarylates located at 328–348nm and 327–353nm for solid films and DMSO solution, respectively. The polyarylate 6a, as an example, exhibited not only aggregation-induced emission (AIE) effect in different fraction tetrahydrofuran/water solution, but also solvatochromism in various polar solvents, markedly. Two reversible pairs of distinct redox peaks were associated with noticeable color changed from original colorless to yellowish orange and green for polymeric film could be observed in the cyclic voltammetry (CV) test. New absorption peaks emerged in near–infrared (NIR) region with increasing voltage in the UV–vis spectra, which indicates these polyarylates can be used as NIR electrochromic materials. These polyarylates performed high contrast of optical transmittance change around 42–53% with the highest coloration efficiency up to 236cm2C−1.

Facile fabrication of hydrolysis resistant phosphite antioxidants for high-performance optical PET films via in situ incorporation

Phosphite antioxidants are extensively used in polyester industry due to extraordinary antioxidative and chromaticity protection capabilities. Unfortunately, they are highly susceptible to hydrolysis leading to reduced antioxidative activity, which remains unsatisfactorily addressed so far. In this work, we have demonstrated the fabrication of hydrolysis resistant hybridized phosphite antioxidants (PSLDH) by physically melt-blending with layered double hydroxides (LDH) based on the hydrolysis mechanism. X-ray diffraction measurements indicate that basically phosphite antioxidants are physically hybridized with the LDH. Accelerated hydrolysis results show that as-fabricated hybridized phosphite antioxidants show much superior anti-hydrolysis capability to the unmodified counterpart because the basic LDH can neutralize the phosphoric acid created during hydrolysis, thus effectively prohibiting the self-catalytic effect. High performance optical poly(ethylene terephthalate) (PET) materials are then synthesized by in situ adding PSLDH in the polycondensation process. Only adding 0.05wt% of the PSLDH containing 10wt% of LDH can remarkably improve the anti-oxidative and chromaticity performances of the resultant PET. This work provides an innovative methodology for developing high-performance value-added chemical additives via facile physical hybridization.

Investigating the influence of conduit residues on polyurethane plates

Converting waste into a product similar to the original one or into another useful product is to save energy, protect natural resources, and bring back to the production cycle what was discarded. In that direction, new polyurethane-based composites have been developed by incorporating 5%, 10%, 15%, and 20% PVC conduit discarded by the construction industry. The objective of this study was to investigate the interaction between the phases of waste incorporation and the effect upon the new material properties. The samples were produced by the polycondensation process. Microstructural analysis revealed a reduction in pore size across the polymer matrix. However, there were no changes in thermal insulation, water absorption, compressive strength, and burning rate tests and in the thermogravimetric analysis and differential scanning calorimetry. The results from this study showed that the replacement of raw material by waste did not affect its properties.

Effects of Poly(cyclohexanedimethylene terephthalate) on Microstructures, Crystallization Behavior and Properties of the Poly(ester ether) Elastomers.

To understand the role of molecular structure on the crystallization behavior of copolyester in thermoplastic poly(ether ester) elastomers (TPEEs), series of poly(butylene-co-1,4-cyclohexanedimethylene terephthalate) (P(BT-co-CT))-b-poly(tetramethylene glycol) (PTMG) are synthesized through molten polycondensation process. The effects of poly(cyclohexanedimethylene terephthalate) (PCT) content on the copolymer are investigated by Fourier transform infrared spectroscopy (FT-IR), 1H and 13C nuclear magnetic resonance (NMR), gel permeation chromatographs (GPC), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical, and visible light transmittance tests. FT-IR and NMR results confirm the incorporation of PCT onto the copolymer. WAXD and DSC indicate that the crystalline structure of the copolymers changed from α-PBT lattice to trans-PCT lattice when the molar fraction of PCT (MPCT) is above 30%, while both crystallization and melting temperatures reach the minima. An increase in MPCT led to an increase in the number sequence length of PCT, the thermal stability and the visible light transmittance of the copolymer, but to a slight decrease in tensile strength and elastic modulus.

Graphene-like carbon nitride nanosheet as a novel sensing platform for electrochemical determination of tryptophan

In this paper, a new and facile strategy has been demonstrated for the electrochemical determination of tryptophan (Trp), based on graphite-like carbon nitride (g-C3N4) nanosheets modified glassy carbon (CNNS/GC) electrode. The g-C3N4 nanosheets were obtained via exfoliating bulk graphitic carbon nitride (bg-C3N4), which was synthesized using a thermal poly-condensation process. The obtained g-C3N4 nanosheets were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM). The results confirmed graphite-like structure with thickness of about 6–8nm. The as-synthesized g-C3N4 nanosheets were closely attached to the surface of GC electrode to construct electrochemical sensor without needing any film-forming agents. The CNNS/GC electrode exhibited good electrocatalytic activity towards Trp, and hereby some parameters, including scan rate and pH effect on Trp determination were investigated. Under the optimum experimental conditions, the oxidation peak currents had good linear relationship with Trp concentrations in the range of 0.1–110μM and a detection limit of 0.024μM (S/N=3) was achieved. In addition, the obtained sensor showed good sensitivity, favorable repeatability, and long-term stability. Finally, the proposed electrochemical sensor has been successfully applied for the determination of Trp concentration in real samples with satisfactory results.

Copolymerization with Polyether Segments Improves the Mechanical Properties of Biodegradable Polyesters.

To improve the properties of poly(butylene succinate) (PBS), a series of poly[(butylene succinate)-co-poly(tetramethylene glycol)]s (PBSTMGs) with different poly(tetramethylene glycol) (PTMG) contents were successfully prepared by the catalyzed melt polycondensation process. The effect of introducing flexible PTMG segments on the properties was investigated, and they were compared to those of PBS. The differential scanning calorimetry results indicated that the melting temperature, crystallization temperature, and crystallinity of PBSTMG copolymers were slightly lower than those of PBS. Furthermore, these thermal parameters decreased gradually with the increase of PTMG content. Dynamic mechanical analysis showed that there was a significant decline of storage modulus (E′) in the overall temperature range of copolymers compared to that of PBS. The incorporation of PTMG did not modify the crystal lattice of PBS according to the wide-angle X-ray diffraction analysis. Because of copolymerization, the size of the spherulites was reduced at high PTMG contents. The soft domain in the copolymers might contribute to the enhanced tear strength of PBSTMG. The elongation at break and impact strength of PBSTMG copolymers were greatly improved as a result of the phase separation structure and lower degree of crystallinity. Especially, when the PTMG content was 10 mol %, the impact strength of the copolymer reached up to 4.5 times that of PBS. In addition, with more soft segments introduced, the biodegradability of the copolymers became much better than that of PBS.

Ionic‐liquid‐assisted three‐dimensional caged silica ablative nanocomposites

ABSTRACTIn this study, we demonstrated a novel three‐dimensional network of thermally stable fumed silica (FS)–resorcinol formaldehyde (RF) nanocomposites via an ionic‐liquid (IL)‐assisted in situ polycondensation process. The study involved subjecting the tailored nanocomposites to thermogravimetric analysis and oxyacetylene flame environment as per ASTM test standards for thermal ablative performance. X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, Raman spectroscopy, and wettability studies were undertaken to underline the improvement correlation in the microstructure and material properties. Significant reductions in the linear ablation rate (66%) and mass ablation rate (26.6%), along with lower back‐face temperature profiles, marked enhanced ablative properties. The increased char yield (33.3%) and higher temperatures for weight losses evinced the improved thermal stability of the modified RF resin. The uniformly dispersed fused nanosilica with a glassy coating morphology on the ablative surface acted as barrier to oxidation. The results signify that the IL‐assisted modification of the RF resin with FS significantly enhanced ablative performance. A viable replacement to the conventional phenolic nanocomposites for thermal ablative applications to buy critical time for the containment and suppression of thermal‐heat‐flux threats is of paramount importance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45328.

Novel electrochromic triphenylamine-based polyamides containing quinolin-8-yloxy group as probes for metal ions

A new series of soluble electrochromic polyamides (PAs) were synthesized from the reaction of 4,4’-diamino-4”-(quinolin-8-yloxy) triphenylamine (DAQTPA) with five dicarboxylic acid via direct polycondensation process, respectively. These amorphous materials showed the decomposition temperature at 5% weight loss was over 400°C in N2 atmosphere. The influence of aliphatic structure for spectroscopic properties of PA was measured by UV–vis and fluorescent (PL) spectroscopies and explained by the theory of the frontier molecular orbitals. It can be easily determined that DAQTPA performs the most strongly responsive to Cu2+ with obvious enhancement in UV–vis and quenching in PL profiles, which are completely different from the response of other metal ions. PAs also showed the exclusively selective response for Cu2+ in UV–vis spectra. A pair of obvious redox peaks was observed in the cyclic voltammetry (CV) test of PAs accompanied with the distinct color changed from original yellowish to green or blue. The PA bearing the pendent quinolin-8-yloxy performed as an electron-donating group was more stable in the electrochemical process.

Mechanical behavior of short bagasse fiber reinforced cardanol-formaldehyde composites

Synthesize of a thermosetting resin based cardanol from cashew nut shell liquid (CSNL) using poly condensation process as composite matrix was carried out. Locally collected sugarcane bagasse fiber was dried in an oven to remove the moisture content. These fibers were then cut into specific average length of 10 mm and 20 mm and made into two different sets of cardanol based bio-composites of varying concentration of 0, 5, 10, 15 and 20 % by compression moulding process. The mechanical properties were evaluated by means of tensile, flexural and impact in addition to water absorption test. Results had shown the enhancement of the mechanical properties with increase in range of bagasse fiber upto 15 weight % in both the sets. Of the two sets, 20 mm length fiber possesses more strength comparatively.

Effect of catalyst type on recyclability and decomposition mechanism of poly(ethylene furanoate) biobased polyester

In the present work, poly(ethylene furanoate) (PEF) was synthesized via two-stage melt polycondensation process, using four different catalysts, namely tetrabutyl titanate (TBT), titanium(IV) isopropoxide (TIS), tin(II) 2-ethylhexanoate (TEH) and dibutyltin(IV) oxide (DBTO). In all reactions, 2,5-dimethylfuran-dicarboxylate (DMFD), ethylene glycol (EG) (1:2 molar ratio) and 400ppm of catalyst were used. The effect of these catalysts on the remelting and decomposition mechanism of PEF was studied. All polyesters were remelted up to three times, and for every melting cycle the intrinsic viscosity (IV) values and the carboxyl end group content were measured. It was found that after every melting, the IV was reduced while the COOH number was increased. Also, all samples have been studied with Fourier Transformed-Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. It was found that the molecular weight reduction also affects the thermal properties of the polyesters. The decomposition mechanism of the prepared polyesters was studied using pyrolysis-gas chromatography/mass spectroscopy (Py-GC/MS).

Eco-Friendly Polythiophene(keto-amine)s Based on Cyclopentanone Moiety for Environmental Remediation

Eco-friendly polythiophene(keto-amine)s 4 a–e containing thiophene-arylidene-thiophene tri-blocks moieties in polymers backbones have been synthesized and characterized for environmental remediation. The synthetic method has been carried out by the interaction of the monomer 2 with different aromatic, cyclic and aliphatic diamines. The polymerization had occurred using polycondensation process in dry benzene as solvent. A new monomer namely, 2,5-bis[4-choloro-acetyl(thiophen-2-ylmethylene)]cyclopentanone 2 was firstly synthesized using the normal condition of Friedel–Crafts reaction by the reaction of 2,5-bis(thiophen-2-ylmethylene)cyclopentanone 1 with chloroacetyl chloride in the presence of aluminum chloride anhydrous. The structure of the new monomer as well as polymers was confirmed by elemental and spectral analyses. Furthermore, solubility, viscometry, SEM and thermal characteristics for the new polymers were tested. All the polymers were freely soluble in formic acid as good example for polar protic solvents. PDTmax and FDT for all the polymers were detected and were in the range 434–467 and 487–533 °C respectively. On the other hand, the analytical competition of the newly synthesized PTKA polymers 4 a and 4 c was also evaluated for a selective extraction of metal ions prior to their determination by inductively coupled plasma-optical emission spectrometry mainly for environmental remediation. The selectivity of PTKA 4a and PTKA 4c towards different metal ions, including Cd(II), Co(II), Cu(II), Cr(III), Fe(III), Ni(II) and Zn(II), was studied. Results of the selectivity study demonstrated that 4 a and 4 c polymers was the most selective towards Cr(III) and Co(II). Adsorption capacity of 4a for Cr(III) was improved by 38.37% in comparison to that of 4 c for Co(II) after only 1 h contact time. Moreover, adsorption isotherm data provided that the adsorption process was mainly monolayer on homogeneous adsorbent surfaces of both PTKA 4 a and PTKA 4 c.

Synthesis of isosorbide-based polycarbonates via melt polycondensation catalyzed by quaternary ammonium ionic liquids

A series of quaternary ammonium ionic liquids (ILs) were synthesized and employed as catalysts for the production of poly(isosorbide carbonate) (PIC) from diphenyl carbonate and isosorbide via a melt polycondensation process. The relationship between the anions of the ILs and the catalytic activities was investigated, and the readily-prepared IL tetraethylammonium imidazolate (TEAI) was found to exhibit the highest catalytic activity. After optimizing the reaction conditions, a PIC with a weight-average molecular weight (Mw) of 25600 g/mol was obtained, in conjunction with an isosorbide conversion of 92%. As a means of modifying the molecular flexibility and thermal properties of the PIC, poly(aliphatic diol-co-isosorbide carbonate)s (PAIC)s were successfully synthesized, again using TEAI, and polymers with Mw values ranging from 29000 to 112000 g/mol were obtained. 13C NMR analyses determined that the PAIC specimens had random microstructures, while differential scanning calorimetry demonstrated that each of the PAICs were amorphous and had glass transition temperatures ranging from 50 to 115 °C. Thermogravimetric analyses found Td-5% values ranging from 316 to 332 °C for these polymers. Based on these data, it is evident that the incorporation of linear or cyclohexane-based diol repeating units changed the thermal properties of the PIC.