Polymer Chains Of Poly Research Articles

Enhanced luminescent properties of poly(sodium acrylate)-based composite and its selective interaction towards copper ions

This study investigates the luminescent properties and metal ion interactions of europium when combined with a polymer chain of poly (sodium acrylate) (PSA) and a phenanthroline (Phen) molecule, which acts as an efficient antenna. The study of interactions between lanthanide ions and various compounds in different matrices is crucial, providing valuable insights into the molecular environment, and enabling a deeper understanding of processes affecting their luminescence. In this study, we investigated the luminescent properties of the Eu(PSA)Phen complex and its remarkable capacity for selective interaction with Cu2+ ions in an aqueous solution. From this selective interaction, we conducted a series of detailed studies that provided valuable insights into the mechanisms of luminescence suppression, information about the europium chemical environment, and other related aspects. The luminescence of Eu(PSA)Phen is significantly quenched by Cu2+ ions, driven by both static and dynamic mechanisms. The presence of the PSA polymer chain and Phen molecules within the composite exerts a profound influence on energy transfer processes, enabling selective responses to Cu2+ ions, even in the presence of competing cations. Additionally, we observed a preferential interaction of the PSA molecule in the Eu(PSA)Phen composite with Cu2+ ions over the N groups of phenanthroline. These findings underscore the compound potential as a versatile tool in various fields, ranging from material science to biosensing, where rapid and selective metal ion detection is of paramount importance.

Structural study of two polymer chains of poly(2-methoxyethyl glycidyl ether)-b-poly(2-ethoxyethyl glycidyl ether) thermoresponsive block copolymers using molecular dynamics simulations

Block copolymers are expected to be applied in a wide variety of fields due to the property of self-assembly. Our group has reported that poly(glycidyl ether) block copolymers exhibited complex temperature response in aqueous solution. In this study, we investigated the two chains of the block copolymer structure and configurations at different temperatures by using MD simulation. The results showed that at low temperatures, the polymer structure is linear and can form micelles, but above a certain temperature, the polymer structure changes to a U-shape and the micelle structure would be destroyed, which is responsible for the complex temperature response.

Synergistically Improving the Thermal Conductivity and Mechanical Strength of PEEK/MWCNT Nanocomposites by Functionalizing the Matrix with Fluorene Groups

AbstractNanofiller reinforcement is an effective method to prepare high thermally conductive polymer‐matrix composites. However, the poor dispersion of nanofillers and high interfacial thermal resistance between the filler and matrix seriously affect the thermal conductivity and mechanical properties of composites. To solve this problem, a small amount of conjugated fluorene group is introduced into the polymer chain of poly (ether ether ketone) (PEEK) to afford the fluorene‐functionalized copolymer matrix (FD‐PEEK). In an in situ polymerization procedure, the matrix non‐covalently binds to multi‐walled carbon nanotubes (MWCNT) to allow highly filled PEEK/MWCNT nanocomposites. With the filler dispersion and matrix–filler interfacial bonding improved, the prepared nanocomposites possess both high thermal conductivity and tensile strength. At the optimal ratio of 2 mol% fluorene groups in the polymer chain, the nanocomposite with 10 wt% MWCNT exhibits an excellent thermal conductivity of 2.41 W m−1 K−1, which is 868% higher than pristine PEEK, with tensile strength remaining 104.3 MPa. The PEEK/MWCNT nanocomposites can be further used as matrix resins to build double‐segregated network multi‐component composites, which contributes to an innovative strategy to design high‐performance thermally conductive materials.

Flame-retardation of thermoplastic polyesters via cyclotetramerization from phthalonitrile to phthalocyanine: Pyrolysis processes and fire behaviour

Flame retardancy is a way to enhance the fire safety performance of polymers, which can slow down the flame spread and reduce the severity of fire events. Phthalocyanines (Pcs) skeletons have unleashed high flame-retardant efficiency in thermosetting resins. However, limited by the high stability and bulky structure of Pcs, how to make this classic macrocyclic structure play its flame retardant advantages in thermoplastic polymers is still a significant challenge. We synthesized flame-retardant copolyesters (CxPET) via chemically incorporating the phenoxyphthalonitrile structures into the polymer chains of poly(ethylene terephthalate) (PET) by melt polymerization. PY-GC–MS tests at 400, 500, and 700 °C are performed to detailedly investigate the pyrolysis processes. The TGA, LOI, and UL-94 tests are carried out to reveal the burning behavior. The LOI, vertical UL-94, and cone calorimeter tests, are used to characterize the flame-retardant properties and the fire behavior. The copolyesters, containing phenoxyphthalonitrile structures, exhibit good flame retardance (LOI 30.0, UL-94V-0 level with no dripping producing). The peak heat release rate (337 ± 32 kW m−2) and TSR (1377 ± 74 m2 m−2) are also reduced by 55.4% and 20.2%, compared with PET. Combining the pyrolysis processes and fire behavior results, the phthalonitrile structures can be quickly transformed into phthalocyanine structures at high temperatures. Further, the formed phthalocyanines play a flame-retardant role via promoting the charring of copolyesters. Therefore, this work supplies an available way to play the flame retardant advantages of phthalocyanine macrocyclic in thermoplastic polymers, and provides key guidance for the design of safer polymers.

Structure of the polymer chain of poly(1,3-pentadiene) synthesized using a stereospecific catalytic system

Structure of the polymer chain of poly(1,3-pentadiene) synthesized using a stereospecific catalytic system

Effect of uniaxial compression on traps of excitons and charge carriers in poly(9-vinylcarbazole) films

The effect of uniaxial pressure (1 × 108 Pa) on the photoluminescence spectra and thermally stimulated luminescence curves of poly(9-vinylcarbazole) has been investigated in the temperature range of 5–295 K. The thermally stimulated luminescence curve of crystalline carbazole has been measured for comparison. The high-temperature wings of the thermally stimulated luminescence curves are approximated by a Gaussian function, the half-width of which characterizes the disorder of energy states of deep structural traps. It is concluded that the pressure inhibits conformational changes of polymer chains of poly(9-vinylcarbazole), which leads to the formation of sandwich-like excimers as well as to an ordering of the spatial arrangement of the side carbazolyl groups. As a result, the concentration of “excimer-forming” centers increases, whereas the degree of disorder of energy states of deep structural traps of charge carriers is reduced by almost half and remains unchanged after the depressurization.

Interpenetrating polymer networks based on polyurethane and organic-inorganic copolymer

The investigation of the features of the formation of interpenetrating polymer networks (IPNs) based on cross-linked polyurethane and organic-inorganic copolymer (OIC) based on hydroxyethyl methacrylate (HEMA) and titanium isopropoxide (Ti(OPri)4) was carried out using the IR spectroscopy method. It has been demonstrated that during the synthesis of organic-inorganic IPNs (OI IPNs), three-dimensional cross-linked structures with the inclusion of (-TiO2-) fragments in the polymer chain of poly(hydroxyethyl methacrylate) are formed. The examinations of the viscoelastic properties and thermal stability of organic-inorganic IPNs by dynamic mechanical (DMA) and thermogravimetric analysis (TGA) showed that the value of Mc decreases with an increase in the content of (-TiO2-) fragments in OI IPN; in addition, the thermal stability of the obtained hybrid OI IPNs increases significantly compared to the parent systems.

High Strength of Physical Hydrogels Based on Poly(acrylic acid)-g-poly(ethylene glycol) Methyl Ether: Role of Chain Architecture on Hydrogel Properties

This investigation was to study the connections between polymer branch architecture of physical hydrogels and their properties. The bottle-brush-like polymer chains of poly(acrylic acid)-g-poly(ethylene glycol) methyl ether (PAA-g-mPEG) with PAA as backbones and mPEG as branch architecture were synthesized and in situ grafted from silica nanoparticles (SNs) to construct hydrogels cross-linked networks in aqueous solutions. The structural variables to be discussed included molecular weight and molar ratio of branch chains, and new aspects of the formation mechanism of physical hydrogels with branch structure in the absence of organic cross-links were present. The results indicated that the differences of polymer chain architecture could be distinguished via their different interactions that are present by gelation process and mature gel properties, such as gel strength and swelling ratio. The gelation occurred at the critical polymer concentration and molecular weight, respectively, and the inorganic/organic (SNs/PAA-g-mPEG) nanoparticles began to entangle and construct the cross-linking networks afterward. The gel-to-sol transition temperature (T(g-s)) and radii of SNs that were encapsulated by polymer chains as a function of time for chains' disentanglement were monitored according to the observation of the dissolution process, and the molecular weight between two consecutive entanglements (M(e)) was calculated thereafter. This study showed that the introduction of branch chain onto the linear backbone significantly promoted the chain interactions and increased entanglement density, which contributed to the hydrogels' network integrity and rigidity, thus illustrating greater elongation at break and tensile strength than the hydrogels formulated with linear polymer chains.

Non-Isothermal Degradation Kinetics of Hybrid Copolymers Containing Thermosensitive and Polypeptide Blocks

Novel, self-associating hybrid copolymers were synthesized via controlled ring-opening polymerization of N-carboxyanhydride of Z-L-lysine (Z-L-Lys-NCA), initiated by amino-functional macroinitiators. A poly(N-isopropylacry-lamide) (PNIPAm)-based macroinitiator containing 10 mol% of polyoxyethylene grafts and a terminal primary amine group in the form of ammonium hydrochloride (PNIPAm-g-PEО) was synthesized and used to initiate the ammonium- mediated ring-opening polymerization of NCA described by Dimitrov and Schlaad [1]. Thus, hybrid copolymers ((PNIPAm-g-PEO)-b-PLys) with controlled molar-mass characteristics and functionality were obtained. The potential applications of PNIPAm-based copolymers in the systems for controlled drug release, immobilization of enzymes and protein purification have aroused great interest in the studies of their properties and behaviour. The thermal stability and thermodynamic properties of the copolymers obtained were studied. The differential thermal analysis of polyfunctional hybrid copolymers (PNIPAm-g-PEO)-b-PLys) showed that thermooxidative destruction occurs in two stages: primary, of the unstable fragments (grafted chains of PEO); and secondary, of the main polymer chains of poly(N-isopropylacry-lamide) and poly(L-lysine). The kinetics of thermal degradation was evaluated and the values of the activation energy of the degradation process, changes of Gibbs free energy, enthalpy and entropy for the formation of the activated complex were also calculated.

Gel Formation and Interpolymer Alkyl Chain Interactions with Poly(9,9-dioctylfluorene-2,7-diyl) (PFO) in Toluene Solution: Results from NMR, SANS, DFT, and Semiempirical Calculations and Their Implications for PFO β-Phase Formation

Interactions between polymer chains of poly(9,9-dioctylfluorene-2,7-diyl) (PF8) have been studied in toluene solution over a wide concentration range using multinuclear NMR spectral and relaxation measurements with both the fully protonated and alkyl chain deuterated polymers, small angle neutron scattering (SANS), together with theoretical calculations using DFT and semiempirical methodologies. Full assignment of the 1H and 13C chemical shifts in the NMR spectra of isolated chains of PF8 has been made using DFT, and are in good agreement with spectra in chloroform and in toluene solutions. Somewhat different behavior is seen in toluene solution, where, upon increasing polymer concentration, broadening of the alkyl chain resonances is seen, consistent with interactions between the side chains. Similar behavior is seen with the 2H resonance of PF8-d34. In both cases, line-narrowing and restoration of the structured alkyl chain resonances is seen upon studying the spectra of concentrated solutions using the...

Dithioester functionalization of poly(cyclohexene oxide) and its application to obtain block copolymers

A new method of introducing dithioester groups into the polymer chain of poly(cyclohexene oxide) is reported. It includes the use of diaryliodonium salt and an aromatic dithioacid as a redox couple to initiate the cationic polymerization of cyclohexene oxide. It was found that the dithioacid by itself cannot start the polymerization of cationic polymerizable monomers; however, in combination with a diaryliodonium salt, an exothermic reaction was produced, yielding a thiocarbonylthio-functionalized polyether. Thermal profiles of the redox polymerizations were determined by means of optical pyrometry. A preliminary study showed that when the poly(cyclohexene oxide) functionalized with dithioester groups was introduced into the radical polymerization of styrene, the polystyryl growing radicals reacted with the dithioester-functionalized polyether to form a block polymer. The amount of polyether actually incorporated into the block copolymer was calculated to be 70% of the initial amount of poly(cyclohexene oxide)/dithiobenzoic acid charged into the reactor. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Poly(ethylene terephthalate) copolymers that contain 5‐tert‐butylisophthalic acid and 1‐3/1‐4‐cyclohexanedimethanol: Synthesis, characterization, and properties

AbstractThe effects of incorporating 5‐tert‐butylisophthalic acid (tBI) and 1‐3/1‐4 cyclohexanedimethanol (CHDM) in the polymer chain of poly(ethylene terephthalate) (PET) on the crystallization behavior and thermal, optical and tensile properties of this polyester (PETGB) were evaluated. These random copolyesters that contained between 0 and 20 mol % of CHDM and between 0 and 10 mol % of tBI units were prepared by esterification followed by melt copolycondensation. The compositions and molecular weights of the copolyesters were determined by 1H‐NMR spectroscopy and viscometry, respectively. The composition of the polyester was consistent with the composition of the feed. The intrinsic viscosities of the copolymers ranged between 0.62 and 0.74 dL/g. The thermal behaviors were investigated over the entire range of copolymer compositions, using DSC under the heating and cooling rate of 20°C/min and TGA. The copolyesters with tBI and CHDM of < 20 mol % were crystallizable, whereas the copolyesters with tBI and CHDM of ≥ 20 mol % were amorphous. They appeared to be stable up to 395°C. The optical transmissions of the amorphous polyesters were more than 88% in the visible region. The mechanical behavior was investigated by performing a tensile test. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 279–285, 2007

Crystallization and properties of poly(ethylene terephthalate) copolymers containing 5- tert-butyl isophthalic units

The influence of incorporating 5- tert-butyl isophthalic units ( t BI) in the polymer chain of poly(ethylene terephthalate) (PET) on the crystallization behavior, crystal structure, and tensile and gas transport properties of this polyester was evaluated. Random poly(ethylene terephthalate- co-5- tert-butyl isophthalate) copolyesters (PET t BI) containing between 5 and 40 mol% of t BI units were examined. Isothermal crystallization studies were performed on amorphous glassy films at 120 °C and on molten samples at 200 °C by means of differential scanning calorimetry. Furthermore, the non-isothermal crystallization behavior of the copolyesters was investigated. It was observed that both crystallinity and crystallization rate of the PET t BI copolyesters tend to decrease largely with the comonomeric content, except for the copolymer containing 5 mol% of t BI units, which crystallized faster than PET. Fiber X-ray diffraction patterns of the semicrystalline PET t BI copolyesters proved that they adopt the same triclinic crystal structure as PET with the comonomeric units being excluded from the crystalline phase. Although PET t BI copolyesters became brittle for higher contents in t BI, the tensile modulus and strength of PET were barely affected by copolymerization. The incorporation of t BI units slightly increased the permeability of PET, but copolymers containing up to 20 mol% of the comonomeric units were still able to present barrier properties.

On the intermolecular crosslinking of PVA chains in an aqueous solution by γ-ray irradiation

We studied how the polymer chains of poly(vinyl alcohol)(PVA) are crosslinked in its O2-free aqueous solution by γ-rays. The static–dynamic laser light scattering method was employed for determining the molecular weight (Mw), hydrodynamic radius (Rh) and radius of gyration (Rg) for the original PVA (Mw=1.0×105) and its radiation products. The γ-ray irradiation from Co60 to the PVA solutions with different concentrations was performed at different dose levels. It was found that both molar mass and size (i.e., Rg and Rh) of the radiation products increased with a dose increase. The magnitude of these increases was enhanced by decreasing the polymer concentration (Cp). In particular, at Cp< the critical polymer concentration leading to microgel formation, very rapid increases in mass and size were observed even at a low dose level. In order to obtain more detailed information about the irradiation-induced crosslinking of PVA, we studied the dose dependence of the molar concentration of intermolecular crosslinks in the system as a function of Cp using the dose curves of Mw. It became apparent that, regardless of Cp, the intermolecular crosslinking reactions were dominant in the initial stage of irradiation. The radiation yield of intermolecular crosslinking was found to increase linearly when increasing Cp, and at Cp> the overlap concentration it asymptotically approached a limiting value estimated from the dimerization of pentane-2,4-diol as a model compound of PVA.

Direct detection of hole transfer processes along the polymer chain by means of picosecond transient absorption and dichroism measurements: poly(vinylnapthalene) systems in 1,2-dichloroethane solution

Picosecond transient absorption spectroscopy and transient dichroism measurements were applied to the direct detection of hole migration processes along the polymer chains of poly(1-vinylnaphthalene) and poly(2-vinylnaphthalene) in 1,2-dichloroethane solution. Electron transfer dynamics in these polymers in the solution was well described by the simple scheme that the cation radical continuously migrates along pendant naphthyl moieties in polymer chain with the charge recombination at the initial position of the charge separation. Hole transfer rate constant of poly(1-vinylnaphthalene) was about twice larger than that of poly(2-vinylnaphthalene). By integrating the present results with the previous investigation on poly(N-vinylcarbazole) system, the factors regulating the rapid hole transfer process were discussed from the viewpoint of electron transfer reactions in condensed phase.

The Effects of Solution Application on Some Mechanical and Physical Properties of Thermoplastic Amorphous Polymers Used in Conservation: Poly(vinyl acetate)s

The tensile properties of solution-cast poly(vinyl acetate) (PVAC) films are determined by the thermodynamic quality of the solvents. Higher strength and lower elongation are evident in polymer films of poly(vinyl acetate) AYAT (Union Carbide) cast from a solution of acetone or an acetone/ ethanol/water mixture, while lower strength and greater elongation are evident in films cast from a solution of chloroform or toluene after drying for 180 days. Films of PVAC-AYAT cast from a toluene solution retained a significant amount (>4%) of solvent, while films cast from the other three solvents retained little solvent (>0.3%). For all polymer films, the glass transition temperature (Tg) was elevated greater than 18°C above the Tg of the bulk polymer. The differences in the tensile properties of the films with little retained solvent is explained on the basis of the thermodynamic quality of the solvents, 1.e., the physical properties of the solution-cast polymer film in the dry state may be affected by the conformation of the polymer chain in the solvent. The polymer chain of poly(vinyl acetate) is relatively extended in the “good” solvent chloroform but is more contracted in the “poorer” and more polar solvent, acetone. The effect of solvent quality on the polymer morphology in the dried film was also demonstrated with Fourier transform infrared spectroscopy (FTIR). Changes in spectral band intensity in the FTIR spectra within a series of poly(Vinyl acetate)s differing in molecular weights can be discerned when these are deposited on KBr from a chloroform solution but not when deposited from an acetone solution.

The Effects of Solution Application on Some Mechanical and Physical Properties of Thermoplastic Amorphous Polymers Used in Conservation: Poly(vinyl acetate)s

The tensile properties of solution-cast poly(vinyl acetate) (PVAC) films are determined by the thermodynamic quality of the solvents. Higher strength and lower elongation are evident in polymer films of poly(vinyl acetate) AYAT (Union Carbide) cast from a solution of acetone or an acetone/ ethanol/water mixture, while lower strength and greater elongation are evident in films cast from a solution of chloroform or toluene after drying for 180 days. Films of PVAC-AYAT cast from a toluene solution retained a significant amount (>4%) of solvent, while films cast from the other three solvents retained little solvent (>0.3%). For all polymer films, the glass transition temperature (Tg) was elevated greater than 18°C above the Tg of the bulk polymer. The differences in the tensile properties of the films with little retained solvent is explained on the basis of the thermodynamic quality of the solvents, 1.e., the physical properties of the solution-cast polymer film in the dry state may be affected by the conformation of the polymer chain in the solvent. The polymer chain of poly(vinyl acetate) is relatively extended in the “good” solvent chloroform but is more contracted in the “poorer” and more polar solvent, acetone. The effect of solvent quality on the polymer morphology in the dried film was also demonstrated with Fourier transform infrared spectroscopy (FTIR). Changes in spectral band intensity in the FTIR spectra within a series of poly(Vinyl acetate)s differing in molecular weights can be discerned when these are deposited on KBr from a chloroform solution but not when deposited from an acetone solution.

Twisted intramolecular charge-transfer phenomenon as a fluorescence probe of microenvironment, effect of polymer concentration on local viscosity and microscopic polarity around a polymer chain of poly(methyl methacrylate)

Fixation du groupe (N,N-dimethylamino)-4 benzoate sur la chaine laterale du polymere. Fluorescence dans l'acetate d'ethyle