A novel type of waterborne fluorescent nanofiber membranes with effectively suppressed ACQ phenomenon: Fabrication,properties, and applications

In this research, a novel type of waterborne fluorescent nanofiber membranes (WNFM) based on fluorescent acrylic latex (FAL) has been developed by electrospinning method using environment-friendly water as the spinning solvent. FALs are synthesized by doping Rhodamine B (Rh B) into acrylate monomers through emulsion polymerization, and then polyvinyl alcohol (PVA) is added to fabricate a series of WNFM via electrospinning process. As the hydrophilic emulsifier sodium dodecyl sulfate enriches on the surface of the latex, a portion of Rh B can be adsorbed onto the surface of FAL and form an electrical double layer to prevent its aggregation, which accounts for the enhancement in fluorescence of FALs. The relationships between the preparation conditions, morphology and properties of WNFM have been studied with a combination of techniques including fluorometry and microscopies. The developed waterborne fluorescent nanofiber membranes demonstrate a good water-resistant property with a linear response of photoluminescence intensity to temperature for many cycles. The study points a new direction to develop the nanofiber membrane using environment-friendly water as a spinning solvent in electrospinning and realize its fluorescent functionalization.     

Fabrication of imprinted photonic films via predesigned multiple UV-polymerizations and their ability to detect solvents and metal ions in aqueous solution

To synthesize photonic films without a chiral dopant, a predesigned multiple photopolymerization process was carried out. The photonic films were prepared by the photopolymerization of a mixture of chiral nematic liquid crystals. After polymerization, the chiral dopant, CB15, was removed and recycled. The imprinted photonic polymer films showed Bragg reflection without the presence of the chiral dopant. Upon the sensing of solvents in aqueous solution, significant color changes and peak shifts were observed by the naked eye and ultraviolet–visible spectroscopy, respectively. A linear calibration curve between the central wavelength of the reflection band of the fabricated imprinting film and the volume ratio of 1,4-dioxane in water was observed. Furthermore, the sensing of chloroform content in methanol, ethanol, and acetone via the imprinted film were also investigated. The results suggest that the synthesized imprinted photonic films can detect different kinds of mixed solvents. The sensing properties of the photonic films were further improved by copolymerization with a rhodamine-derived monomer. The synthesized modified photonic films can detect heavy metal ions in aqueous solution. This study reports a novel, recyclable, and easy approach to detect organic solvents and copper ions in aqueous solution.     

3D printing of shape memory polymers

Shape memory polymers (SMPs) are polymers which ''remember'' their original shape and can return to it after deformation, if an external stimulus—often an increased temperature – is applied. Some SMPs can be 3D printed, typically by fused deposition modeling (FDM). The most well-known SMP is poly(lactic acid), which belongs to the most often used materials in FDM 3D printing. There are; however, many more SMPs which can be 3D printed to combine the possibilities to prepare new, sophisticated shapes with the opportunity to restore these shapes after undesirable or intentional deformation. This review gives an overview of several 3D printable SMPs, their mechanical characteristics and their possible applications.     

Polythiophene based fluorescent probe for copper ions with high sensitivity

Two new conjugated polymers poly{3‐({4‐[(2‐hydrazino‐2‐oxoethyl)(methyl)amino]cyclohexylidene}methyl)thiophene}( P1 ) and poly{3‐({4‐[(3‐hydrazino‐3‐oxopropyl)(methyl)amino]cyclohexylidene}methyl)thiophene}( P2 ) were synthesized, and their optical properties were investigated. P1 exhibited excellent selectivity toward Cu²⁺ ions in 50% water solution, the fluorescence color of P1 changed distinctly from greenyellow to colorless in the presence of Cu²⁺ under UV‐light, while introduction of other metal ions could not induce such significant variation. Moreover, highly sensitive detection of Cu²⁺ ions was demonstrated in 90% water solution. Its high metal‐chelating capability allowed Cu²⁺ recognition with a detection limit of 3.2 × 10^?10 M. These results indicated that this kind of nonionic polymer containing multidentate ligand could be used as a highly selective and sensitive chemosensor for Cu²⁺ detection. The proposed binding mode of P1 with Cu²⁺ was supported by DFT calculation using Gaussian 03. Unlike P1 , P2 showed no obvious fluorescent change in the presence of various metal ions due to its space steric hindrance resulted from N/O distribution on the side chain of P2 . © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42440.     

Outstanding performance of parylene polymers as electrets for energy harvesting and high-temperature applications

Parylene C is used in many applications due to its high properties but it remains a material with moderate performance as long as it is intended for use as an electret. Hence, the generally accepted idea, rightly so, in the scientific and industrial community not to necessarily select parylene (i.e., parylene C) for applications where the endurance of the electret is a strong criterion. Our study provided a new perspective on the performance of parylenes as electret. In this case, we will talk about fluorinated Parylenes of the VT-4 type and especially AF-4 variant. Their thermal stability is outstanding and a charge stability is almost total up to 100 °C. A 50% reduction in the charge is recorded at a temperature as high as of 220 °C (9 μm thick Parylene AF-4), making it one of the most efficient polymer electrets to date. Negatively and positively charged Parylene AF-4 electrets presented similar performance over long durations, which is out of ordinary for the commonly employed polymeric electrets. Finally, these fluorinated polymers are therefore particularly promising new candidates for applications in electret-based converters for energy harvesting. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48790.     

Optical sensor based on fluorescent PMMA/PFO electrospun nanofibers for monitoring volatile organic compounds

The development of polymeric materials with superior electrical and/or optical properties is highly demanded for designing optical gas sensors, where conjugated polymers play an important role due to their π‐electron conjugation. However, usually the low processability and high cost of these materials hinder technological applications. Here we report on a simple route to develop highly fluorescent electrospun nanofibers of poly(methyl methacrylate) (PMMA) containing low contents of polyfluorene (PFO). The PMMA_PFO nanofibers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, while the luminescence properties changes were evaluated by exposing the PMMA_PFO nanofibers to distinct volatile organic compounds (VOCs) including ethanol, toluene, tetrahydrofuran, acetone, dichloromethane, and chloroform. The changes in luminescence properties, specifically fluorescence quenching, of PMMA_PFO nanofibers were analyzed in terms of conformational changes from glassy‐phase to β‐phase of PFO when the nanofibers were exposed to the VOCs. The developed nanostructured platform showed a suitable response to detect chloroform, with linear responses in the concentration range from 10 to 300 ppm and from 350 to 500 ppm and limits of detection of 47.9 and 15.4 ppm, respectively. The results suggest the PMMA_PFO electrospun nanofibers are highly potential materials for optical gas sensor applications based on luminescence quenching. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46128.     

Opal photonic crystal double-network hydrogel for visual detection through structural color and fluorescent responsiveness

Photonic crystal hydrogels are widely used in the field of visual detection, based on the response of the structural color to external stimulus, such as pH, temperature, near-infrared light, and so on. Here, we develop an opal photonic crystal hydrogel by combining polystyrene (PS) photonic crystals with a fluorescent double-network hydrogel and focus on both its visual detection function and mechanical property. The opal hydrogel is composed of nanocomposite hydrogel as the first network and ionic crosslinked hydrogel as the second network. The introduction of PS photonic crystals and terbium ions endows the opal hydrogel distinctive structural colors and fluorescence, respectively. Because of volume changes, the structural color of the opal hydrogel selectively responses to metal ions and organic solvents. Attributing to the ion exchange interaction, the opal hydrogel exhibits fluorescent responses to various metal ions. Combining the responsiveness of structural color and fluorescence, a visual dual-detection mode is set up, with better detection sensitivity and selectivity. Moreover, the characteristics of nanocomposite and double-network crosslinking ensure the opal hydrogel enough mechanical properties to undergo cycle visual detection. Consequently, the fabricated opal hydrogel is promising for use in visual detection to multiple substances in single- or dual-detection mode.     

Triglycine sulphate and its deuterated analog in polyurethane matrix for thermal/infrared detection: A comparison

Composites comprising of polycrystalline triglycine sulphate (TGS) or its deuterated analog (DTGS) in powder form dispersed in polyurethane (PU) are synthesized for pyroelectric sensor applications. TGS and DTGS have high pyroelectric coefficients, but are susceptible to humidity, and PU is inherently electroactive. So composites made of TGS or DTGS dispersed in PU can be expected to have high pyroelectric coefficient as well as immunity to humidity. Composites with inclusion volume fraction between 0 and 0.25 are prepared, and their dielectric, pyroelectric, and thermal properties measured. In general, deuteration leads to decrease in dielectric constant and specific heat, but increase in thermal conductivity. The pyroelectric coefficient and figures of merit get enhanced significantly with deuteration as well as inclusion volume fraction. Comparison with similar composites shows that these samples have the highest values for figures of merit, indicating their potential use as thermal/infrared detectors that are immune to humidity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42250.     

Infrared spectral analysis of low concentration magnetoactive polymers

This work concerns an area of magnetoactive polymer (MAP) research seldom considered. Traditionally only MAP with high concentrations of magnetic filler (typically between 10 and 90 wt%) have been investigated. This article deals with a hitherto neglected aspect of research, namely MAP containing lower magnetic filler concentrations (1 to 3 wt%). This article utilizes a range of spectroscopic analysis methods (Raman and FTIR) and their applicability to MAP characterization at wavelengths ranging from 2.5 to 25 μm. Particular attention is paid to low carbonyl iron particle (CIP) concentrations in MAP for which the emergence of capillary doublets at a critical 2 wt% concentration is revealed. This results in measurable magnetic field-dependent changes in IR absorption at a wavelength of 4.255 μm together with a detectable CO₂ susceptibility. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals Inc. J. Appl. Polym. Sci. 2020 , 137, 48366.     

Conformational and hydrodynamic parameters of hyperbranched pyridylphenylene polymers

Hydrodynamic and optical methods were applied to study conformational and physical properties of hyperbranched pyridylphenylene polymers in dilute solutions. The samples were synthesized using Diels–Alder polycyclocondensation. It was demonstrated that hydrodynamic properties of the studied macromolecules were typical for compact non‐percolated spheres. Optical and electro‐optical methods revealed information regarding the shape and asymmetry of the macromolecules (p ≈ 1.4). The contributions of optical shape effect to the observed flow birefringence of polypyridylphenylene solutions and intrinsic anisotropy of polarizability were evaluated and analysed. It was shown that varying the polymer composition (i.e. the degree of branching) caused considerable changes in the anisotropy of optical polarizability of the polymers. Dramatic difference of the electro‐optical properties in non‐polar (toluene) and polar (tetrachloroethane) solvents was found; this difference was related to the orientational correlation of polar solvent molecules with respect to the macromolecules. Dynamic properties were studied by non‐equilibrium electric birefringence which had a reasonable agreement with the dimensions estimated from hydrodynamic data. © 2016 Society of Chemical Industry     

Synthesis,characterization, and Pb2+ ion sensing application of hexa‐armed dansyl end‐capped poly(ε‐caprolactone) star polymer with phosphazene core

Novel hexa‐armed dansyl end‐capped poly(ε‐caprolactone) (PCL) star polymer with phosphazene core ( P2 ) was prepared via ring opening polymerization (ROP) and esterification reactions. P2 showed dual fluorescence emission when excited at 328 nm in acetonitrile : water (6 : 4) due to twisted intramolecular charge transfer (TICT) between dimethylamino and naphthalene units in the dansyl moiety. TICT emission band (A band) in the emission spectra red‐shifted with increasing solvent polarity. P2 responded to the addition of Pb²⁺, Hg²⁺, Co²⁺, Cd²⁺, Mn²⁺, and Zn²⁺ metal ions by decreasing TICT emission band with slight bathochromic shifts. The highest quenching efficiency was observed for Pb²⁺ ion with Stern–Volmer constant of 324.74M^?1. The Stern–Volmer plot for Pb²⁺ was rather linear with the increasing concentration of the quencher, indicating a dynamic (collisional) quenching mechanism. Stern–Volmer constants for Hg²⁺, Co²⁺, Cd²⁺, Mn²⁺, and Zn²⁺ ions were found to be 212.33, 189.21, 36.24, 20.84, and 20.69, respectively. Besides, the highest quenching efficiency (94.24%) was attained in the presence of Pb²⁺, suggesting that P2 could be employed as a potential Pb²⁺ chemical probe. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42380.     

Spray coating thin polymeric sensor films for Au3+

A novel polymeric sensor of the poly(sodium-4-styrenesulfonate) (PSS)-modified rhodamine B derivative (Rho) was synthesized using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N,N′-dimethylpyridin-4-amine (DMAP) as coupling reagents to obtain PSS-Rho4 in 21% yield. The characterization and “Off–On” sensing phenomena were established through UV–Vis, fluorescence, NMR, and FTIR techniques. The PSS-Rho4 showed high selectivity and sensitivity for Au³⁺ over other metal ions. Upon the addition of Au³⁺, significant color change and “Off–On” fluorescence were observed due to a cation Au³⁺ induced spirolactam ring-opening process with detection limit down to micromolar values (1.2 μM). In addition, spray coating thin polymeric sensor films were produced onto the surface of material (PSS-Rho4-ITO and PSS-Rho4-filtered paper) providing a fast, portable, and easy-to-use molecular device for the detection of Au³⁺ in the real system. Reversibility was evaluated by rinsing with EDTA solution under basic condition. We believe that, this approach provides a sensitive and accurate method for the detection of Au³⁺ in environmental and biological applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48273.     

Pyrene‐functional star polymers as fluorescent probes for nitrophenolic compounds

Novel tetra‐armed star‐shaped styrenic copolymers with pyrene side groups [ (S1‐S3)‐Pyr ] were prepared and employed as fluorescence sensing probe for fast and sensitive determination of nitroaromatic compounds. (S1‐S3)‐Pyr depicted characteristic pyrene monomer emission signals as well as broad excimer bands in their fluorescence emission spectra due to close proximity of the pyrene groups on the polymer chains and the ratio of monomer to excimer emission intensities gradually decreased as the pyrene content of the star polymers were increased from S1‐Pyr to S3‐Pyr . The highest quenching efficiency in the presence of 25 equivalent nitroaromatics was observed for 2,4,6‐trinitrophenol/picric acid (99.4%) followed by 2,4‐dinitrophenol (84.2%), 4‐nitrophenol (82.6%), 2,4,6‐trinitrotoluene (44.0%), 2,4‐dinitrotolunene (32.6%), and 4‐nitrotoluene (28.8%). Superior quenching efficiencies of nitrophenolic compounds were ascribed to their strong binding affinity for (S1‐S3)‐Pyr due to the acidity of phenolic hydroxyl units. Besides, quenching ratios of S1‐Pyr , S2‐Pyr , and S3‐Pyr were measured to be very close to each other. Thus, (S1‐S3)‐Pyr are considered to be highly selective and sensitive fluorescence probes for phenolic nitroaromatic compounds. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46310.     

Cu2+ sensing via noncovalent complexes of fluorescent whitening agents and imidazole-based polymeric dye transfer inhibitors

Fluorescent whitening agents (FWAs) and polymeric dye transfer inhibitors (DTIs) are widely used in detergent formulations to combat garment yellowing, fading, and discoloration. We report a new application for these inexpensive, mass-produced, laundry additives as sensitive fluorescence “turn-off” sensors for Cu²⁺. We show that Cu²⁺-sensitive FWA–DTI complexes form spontaneously when aqueous solutions of FWA and imidazole-based DTI are mixed. We also show that the imidazole groups present in the resulting fluorescent FWA–DTI complex selectively bind Cu²⁺, a potent fluorescence quencher, to form nonfluorescent FWA–DTI-Cu²⁺ complexes. Our Cu²⁺-sensing FWA–DTI complexes are completely water-soluble and have a Cu²⁺ detection limit of ~ 0.14 μM in water. Our simple approach not only converts the Cu²⁺-insensitive FWAs into sensitive fluorescent probes for the metal ion but also significantly enhances the brightness of triazinylaminostilbene FWAs. The present study provides a facile, synthesis-free strategy for producing inexpensive fluorescent sensors for Cu²⁺. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48915.     

Determination of moisture content of polyamide 66 directly from combination region near‐infrared spectra

The hygroscopic nature of polyamide (PA) polymers motivates the development of analysis tools for use in assessing their moisture content. Among possible analysis techniques, near‐infrared (near‐IR) spectroscopy is non‐destructive, requires little or no sample preparation, and is compatible with sample thicknesses on the order of mm. The work reported here makes use of transmission near‐IR spectroscopy in the combination region (5000–4000 cm^?1) to develop a protocol for assessing the moisture content of PA 66 samples directly from their spectral intensities after preprocessing with the standard normal variate transform and partial least‐squares. The method is compatible with online or continuous monitoring applications and can be calibrated without the use of destructive reference measurements such as thermogravimetric analysis. The long‐term calibration performance of the technique is evaluated, and on a scale of 0–100% moisture uptake, the standard error of prediction is found to average 1.4% over 6 months. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40645.     

Thermomechanical effects in the torsional actuation of twisted nylon 6 fiber

Thermally induced torsional and tensile actuators based on twisted polymeric fibers have opened new opportunities for the application of artificial muscles. These newly developed actuators show significant torsional deformations when subjected to temperature changes, and this torsional actuation is the defining mechanism for tensile actuation of twisted and coiled fibers. To date it has been found that these actuators require multiple heat/cool cycles (referred to as “training” cycles) prior to obtaining a fully reversible actuation response. Herein, the effect of annealing conditions applied to twisted nylon 6 monofilament is investigated and it is shown that annealing at 200 °C eliminates the need for the training cycles. Furthermore, the effect of an applied external torque on the torsional actuation is also investigated and torsional creep is shown to be affected by the temperature and load. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45529.     

A versatile radiochromic dosimeter for low‐medium gamma radiation and its application to food irradiation

This article presents a novel radiochromic film for selective detection of low‐medium (0–10 kGy) gamma radiation (⁶⁰Co) doses. This dosimeter is based on a printed fluorescent multilayer structure comprising a paper substrate having layers of copper phthalocyanine (DY220) (a green emitter material) on the bottom, and layers of poly[2‐methoxy‐5(2′‐ethylhexyloxy)‐p‐phenylenevinylene] (MEH‐PPV) (a green‐light absorber, red emitter, and radiation sensitive polymer) on the top. The effect of gamma radiation on the optical properties of DY220/MEH‐PPV was described: it was observed as a strong correlation between radiation dose and fluorescent, color coordinates for CIE (1931) chromatic diagram, and Pantone color reference of the dosimeter. The rate of these changes can be altered by manipulation of top–bottom layers to represent easily the radiation dose to be determined in a wide range. This versatile dosimeter has many uses in the field of food radiation for monitoring, quality assurance, and control of the gamma radiation process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45729.     

Synthesis and characterization of novel aromatic condensation polymers containing rigid benzoxazole pendent groups

A new aromatic diamine monomer containing benzoxazole substituents was prepared by a multistep synthesis starting from 1,4‐dibromo‐2,5‐difluorobenzene. The diamine was polymerized with commercial aromatic dianhydride or dicarboxylic acid chloride monomers to provide several different poly(amic acid)s and polyamides with their inherent viscosities in the range of 0.24–0.46 dL/g. Thermal properties of these polymers including thermal imidization of poly(amic acid)s into polyimides were investigated by using FTIR, DSC, and TGA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 178–185, 2004     

Synthesis and characterization of novel dihydrobenzoxazine resins

Three dihydrobenzoxazines are synthesized from bisphenol A (BPA), 4,4′‐biphenol (BIP), and dicyclopentadiene phenol adduct (DCPD). Polydihydrobenzoxazine containing 4,4′‐biphenol (BIPDB) had the most rigid structure of the three and was found to possess the best mechanical and thermal properties. The glass transition temperature of BIPDB was 206°C, and that of BPA‐type polydihydrobenzoxazine (BPADB) and dicyclopentadiene type polydihydrobenzoxazine (DCPDDB) were 184 and 183°C, respectively. DCPDDB, with a rigid hydrophobic cycloaliphatic structure, was found to possess excellent properties such as low moisture absorption, low dielectric constant, low polarization. The resulted polymer from DCPDDB had a dielectric constant of 2.94U, which was better than that of polymers derived from BPA (3.31U), BIP (3.45U), and traditional phenolic resin (3.9–4.0U). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 342–347, 2006     

Poly(N‐isopropylacrylamide) microgel‐based etalons for determining the concentration of ethanol in gasoline

A device composed of a poly (N‐isopropylacrylamide)‐based microgel layer sandwiched between two thin gold layers was used as a platform for determining the amount of ethanol in gasoline (octane number of 87). This device, also known as an etalon, has unique optical properties, which depend on the diameter of the microgels that make up the device. We show that the optical properties of the device depend on the concentration of the ethanol in gasoline samples. Specifically, as the reflectance peaks shift to higher wavelength, the visual color of the device changes from green to red up to 12% (v/v) ethanol. We show that the response was consistent from sample to sample and that the devices are reusable at least three times. We went on to show that the response did not depend on the source of the gasoline, and that the etalon's response is specific to ethanol compared to other common solvents found in gasoline. The performance of these devices make them potentially useful for detecting ethanol in gasoline at the time of gasoline purchase, to determine if the gas being purchased has been adulterated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42106.