Absorption Of Polymers Research Articles

High voltage insulation and gas absorption of polymers in high pressure argon and xenon gases

High pressure gas time projection chambers (HPGTPCs) are made with a variety of materials, many of which still await proper characterization in high pressure noble gas environments. As HPGTPCs increase in size toward ton-scale detectors, assemblies become larger and more complex, creating a need for detailed understanding of how structural supports and high voltage insulators behave. This includes identification of materials with predictable mechanical properties and without surface charge accumulation that may lead to field deformation or sparking. This paper explores the mechanical and electrical effects of high pressure gas environments on insulating polymers PTFE, HDPE, PEEK, POM and UHMW in argon and xenon, including studying gas absorption, swelling and high voltage insulation strength.

Proof of concept for a model of light reflectance of plastics floating on natural waters

Remote sensing of plastic littering natural waters is an emerging field of science with the potential to provide observations on local to global scales. We present the verification of a theoretical reflectance model of sunlight interacting with a water surface littered with buoyant plastic objects. We measured a few common litter items of different polymers as well as shapes, transparencies, and surface roughnesses. Spectral reflectance measurements in the field were backed up with measurements in the laboratory of coefficients of total and diffuse reflectance, transmittance and absorption. We evaluated a single-band algorithm for 850 nm wavelength and a dual-band algorithm using a second wavelength at a polymer absorption band between 1660 and 1730 nm. Both algorithms were plastic litter type specific. Our findings show that for interpreting spectral remote sensing of floating plastic, physical properties that control geometrical optics should complement information about the absorption spectra of the polymer.

TCT-666 Safety Evaluation of the Biodegradable Polymer-Based Sirolimus-Eluting Stent with Faster Drug Eluting Rate and Polymer Absorption Kinetics in Complex Patient and Lesion Subgroup of the PANDA III Trial

Previous reports from the PANDA III trial had proven that the BuMA (SinoMed, Tianjin, China) biodegradable polymer (BP) sirolimus-eluting stents (SES), with faster drug eluting rate and polymer absorption kinetics, was non-inferior to the Excel (JW Medical, Weihai, China) SES in an all-comer

All organic near ultraviolet photodetectors based on bulk hetero-junction of P3HT and DH6T

The effect of oligomer concentration on the performance of polymer and oligomer blended system based photo-detectors was investigated. Improvement in dark rectification ratio and photoresponse of diode were observed in the blended system photodetectors compared to pristine polymer based photodetectors. The photodetectors fabricated with poly(3-hexylthiophene) (P3HT) and α, ω-di-hexyl-sexithiophene (DH6T) were tuned to two different wavelengths namely 525 nm and 400 nm respectively, corresponding to the maximum of the absorption of polymer and oligomer materials respectively. It was observed that the effective conjugation length and disorder in the polymer chains critically affect the photoresponse of organic optoelectronic devices. In this study, improvement in effective conjugation length and disorder were observed as the concentration of DH6T in the blend was increased; leading to the enhancement in the photoresponse of the fabricated device with these blends. Herein, with the increase of DH6Tconcentartion in the blended thin films, the photoresponsivity of fabricated photodetectors towards near UV at ∼400 nm wavelength in addition to the 525 nm wavelength was found to be increased. Comparable photosensitivity (∼1.6 × 103) and responsivity (∼18 A W−1) were achieved for both the wavelengths separately, in the blended photodetectors fabricated with a DH6T concentration of 40%. Such devices tuned to dual wavelength may also find their application in the field of optically switched logic gates.

P5525A meta-analysis of randomised controlled trials to compare safety and efficacy of everolimus/sirolimus bioabsorbable polymer with second-generation durable-polymer drug eluting stents

Background: Progress in the platforms for DES is aimed at improving safety and outcomes. Second-generation DESs have a biocompatible durable polymer (DP), in addition to bioabsorbable polymers (BP). The benefit of BP is to remove the polymer-triggered inflammatory stimulation associated with DP. There is evidence to suggest BP-DESs are non-inferior to the current generation DES at 12 months. The time course for polymer absorption varies between stents and may take from 4 to 15 months. Hence the potential benefits of BP-DES over DP-DES can only be tested over a longer period, to overcome the time taken for polymer absorption. Purpose: The purpose of the meta-analysis was to compare the safety and efficacy outcomes of BP-DES over a long-term follow-up. Methods: A thorough computer-based search using Ovid MEDLINE, EMBASE, Google Scholar, and PubMed databases was conducted up to 11 November 2017. We only included randomised studies (RCT) comparing clinical outcomes between the BP-DESs and DP-DESs. Only studies where data were available for a minimum of 5 years were included. Safety (Stent thrombosis (ST) and reinfarction) and efficacy (target lesion revascularization (TLR), cardiac mortality) were analysed. Results: The literature search yielded 445 citations. After going through the abstracts and full-texts of the articles we included 5 RCTs where 5-year follow-up data was available. The information about the included studies, stent platform, drug and type of polymer is provided in Table 1.There was no difference in the ST (OR 0.71, 95% CI 0.47 –1.09, I2 = 31%, P=0.12), reinfarction (OR 1.01, 95% CI 0.85 –1.21, I2 = 0%, P=0.89), cardiac mortality (OR 1.00, 95% CI 0.81 –1.23, I2 = 0%, P=0.98), all cause mortality (OR 0.95, 95% CI 0.80 –1.14, I2 = 21%, P=0.61) and TLR (OR 0.80, 95% CI 0.58–1.11, I2 = 68%, P=0.18). Furthermore, there was no difference in the very late ST (OR 0.49, 95% CI 0.19 –1.30, I2 = 56%, P=0.15).

A meta-analysis of randomized controlled trials to compare long-term clinical outcomes of bioabsorbable polymer and durable polymer drug-eluting stents.

The durable polymer (DP) of a drug-eluting stent (DES) serves no function once drug elution is complete. To ascertain the benefits of bioabsorbable polymer (BP) over DP-DESs requires a longer follow-up period, to overcome the time taken for polymer absorption. The primary aim of this meta-analysis was to compare the safety and efficacy of BP-DES with the DP-DES over mid (2 years) to long-term (3-5 years) follow-up. A thorough computer-based search was performed using Ovid MEDLINE, EMBASE, Google Scholar, and PubMed databases. We only included randomized controlled studies comparing clinical outcomes between BP-DESs and DP-DESs. Only studies where data were available for a minimum of 2 years were included. A separate analysis of 2-year outcomes and 3- to 5-year outcomes were conducted. Data from 6 and 8 studies were included in 3- to 5-year and 2-year follow-up, respectively. There were no differences between stent groups in cardiac mortality, stent thrombosis (ST), target lesion revascularization, target vessel failure, and reinfarction rates for either 2-year or 3- to 5-year follow-up. Subgroup analysis according to strut thickness (<100 µm, >100 µm) of BP-DES demonstrated similar results. The analyses of ST and very late ST favoured BP-DESs but did not reach statistically significant level. There were no differences in clinical outcomes between BP-DESs and DP-DESs over mid- and long-term follow-up.

On the role of hydrogen bonding on water absorption in polymers

A kinetic model is proposed for the absorption of water in polymers. The process of bonding-debonding water molecules is described by two opposite reactions with different rate constants, and the key role of the concentration of traps by hydrogen bonding in the polymer matrix is highlighted. These three parameters are combined such that an equation is obtained that generalizes the model proposed by Carter and Kibler, with an additional, crossed, term. Numerical application is performed for the diffusion-absorption of water in a plane polymer sheet, and the parameter ranges where a quasi-Fickian water uptake curve is obtained are defined. The associated apparent diffusivity is shown to obey a hyperbolic variation with equilibrium water uptake for homologous series of polymers, which is in agreement with previous experimental observations.

Mechanochemical changes in absorption and fluorescence of DDM-containing epoxies

Mechanochemical changes in absorption or fluorescence in solid polymers are important for the development of new methods of damage sensing, and must be demonstrated in structural polymers such as epoxies for widespread use. With this in mind, we have observed that diamine-cured epoxies containing 4,4′-diaminodiphenyl methane (DDM) framework display mechanochemical changes in both absorption and fluorescence. Samples change from original “blue” to mechanochemically activated “red” fluorescence in response to uniaxial compressive deformation beginning in the early stages of strain hardening. Accompanying the “red” fluorescence is an increase in radical concentration; both are impermanent in time, suggesting the reactive intermediate as the fluorophore. Orange and green chromophores are generated by compression as well; the orange chromophore is the red-emitting fluorophore while the green chromophore is non-fluorescent at ambient conditions. Our work indicates that the DDM structure is the origin of the mechanochromic responses, and stoichiometric variation and degree of cure are strong determinants for whether orange or green chromophores will form. Based on these results the red-emitting orange chromophore is proposed as a reactive radical intermediate of core DDM structure, generated by bond scission reactions on the epoxy network. The green chromophore is a quinoidal methine resulting from the intermediates.

Newest models and calculation schemes for quantitative analysis of physical properties of polymers

New models and calculation schemes have been developed for the quantitative analysis of a number of physical properties of polymers — glass transition temperature, flow temperature of polymer nanocomposites, thermal conductivity, boiling point of polymer solutions, water absorption and water permeability of polymers and nanocomposites, strength, viscosity, storage and losses moduli, refractive index and dielectric constant. All calculation schemes are based on the structure of linear and cross-linked polymers; their degree of crystallinity, free volume, the effect of temperature, the composition of copolymers and homogeneous mixtures of polymers, the concentration of nanoparticles, their shape, size distribution, orientation angles, the structure of polar groups grafted to the surface of nanoparticles, the energy of intermolecular interactions are taken into account. All computational schemes are computerized and allow calculations to be carried out automatically after the introduction of the structure of a repeating unit of polymer unit into the computer, as well as the shape and size of nanofillers.

A Five-Year Follow-Up of Randomised Studies Comparing Outcomes Between Bioabsorbable-Polymer and Durable-Polymer Drug-Eluting Stents: Systematic Review and Meta-Analysis

Background: Bioabsorbable polymer drug-eluting stents (BP-DES) are non-inferior to current generation DES and bare metal stents (BMS) outcomes at 12 months [ 1 Natsuaki M. et al. JACC. 2013; 62: 181-190 Crossref Scopus (186) Google Scholar , 2 Smits P.C. et al. Lancet (London. England). 2013; 381: 651-660 Google Scholar , 3 Raber L. et al. JAMA. 2012; 308: 777-787 Crossref PubMed Scopus (252) Google Scholar ]. The assumed benefit of BP-DES is to remove the polymer-triggered inflammatory stimulation associated with durable-polymer DES (DP-DES). However, potential benefits of BP-DES may require a longer follow-up period, to overcome the time taken for polymer absorption. The purpose of this meta-analysis was to compare the safety and efficacy outcomes of BP-DES over a long-term follow-up.

N-Benzoyl dithieno[3,2-b:2\u2032,3\u2032-d]pyrrole-based hyperbranched polymers by direct arylation polymerization

BackgroundAlthough poly(N-acyl dithieno[3,2-b:2′,3′-d]pyrrole)s have attracted great attention as a new class of conducting polymers with highly stabilized energy levels, hyperbranched polymers based on this monomer type have not yet been studied. Thus, this work aims at the synthesis of novel hyperbranched polymers containing N-benzoyl dithieno[3,23,2-b:2′,3′-d]pyrrole acceptor unit and 3-hexylthiophene donor moiety via the direct arylation polymerization method. Their structures, molecular weights and thermal properties were characterized via 1H NMR and FTIR spectroscopies, GPC, TGA, DSC and XRD measurements, and the optical properties were investigated by UV–vis and fluorescence spectroscopies.ResultsHyperbranched conjugated polymers containing N-benzoyl dithieno[3,23,2-b:2′,3′-d]pyrrole acceptor unit and 3-hexylthiophene donor moiety, linked with either triphenylamine or triphenylbenzene as branching unit, were obtained via direct arylation polymerization of the N-benzoyl dithieno[3,23,2-b:2′,3′-d]pyrrole, 2,5-dibromo 3-hexylthiophene and tris(4-bromophenyl)amine (or 1,3,5-tris(4-bromophenyl)benzene) monomers. Organic solvent-soluble polymers with number-average molecular weights of around 18,000 g mol−1 were obtained in 80–92% yields. The DSC and XRD results suggested that the branching structure hindered the stacking of polymer chains, leading to crystalline domains with less ordered packing in comparison with the linear analogous polymers. The results revealed that the hyperbranched polymer with triphenylbenzene as the branching unit exhibited a strong red-shift of the maximum absorption wavelength, attributed to a higher polymer stacking order as a result of the planar structure of triphenylbenzene.ConclusionBoth hyperbranched polymers with triphenylamine/triphenylbenzene as branching moieties exhibited high structural order in thin films, which can be promising for organic solar cell applications. The UV–vis absorption of the hyperbranched polymer containing triphenylbenzene as branching unit was red-shifted as compared with the triphenylamine-containing polymer, as a result of a higher chain packing degree.

Effect of nanofiller geometry on the energy absorption capability of coiled carbon nanotube composite material

Experimental evidence shows that coiled carbon nanotube (CCNT) simultaneously improves stiffness, fracture toughness, impact energy absorption and vibration damping properties of polymers. This makes a multifunctional composite, which is a good candidate for automobile or airplane structures. In this paper, a multi-scale model has been developed to study the damage initiation in polyethylene reinforced by CNTs and CCNTs. The cohesive zone model has been utilized to model the fiber-matrix debonding. The cohesive zone parameters have been obtained from atomistic simulation. Representative volume element (RVE) is constructed to obtain stress-strain curve. The effects of bonding strength, volume fraction (VF), CNT direction and effective geometric parameters of CCNTs and CNTs on mechanical properties and stress-strain curves of designed nanocomposites has been investigated using finite element method. Results show nanocomposites reinforced by CCNT have higher toughness than nanocomposites reinforced by CNT. We can relate this properties improvement to the shape of the coiled carbon nanotube which induces mechanical interlocking when the composites are subjected to loading. In fact, the coiled configuration of the nanotubes enhance the fracture toughness as well as mechanical strength of the composites even there is no direct chemical bonding between the nanotubes and matrix.

Hydrodynamic fluorescence emission behavior of molecular rotor-based vinyl polymers used as viscosity sensors

A molecular rotor compound containing an allyl group (aMR) was synthesized and copolymerized with the vinyl monomers methyl methacrylate (MMA), styrene (St), and 2-hydroxyethyl methacrylate (HEMA). The absorption and fluorescence (FL) emission maxima of the solution of aMR in THF were observed at 445 and 485 nm, respectively. The FL quantum yield (FLQY) of aMR in THF was quite low (0.21%). However, it was found that the FL intensity significantly increased as the viscosity of the fluid increased. This change was expressed using the Förster-Hoffmann equation, log I = C + x log η, where I and η are the FL intensity of the probe and the viscosity of the fluid, respectively. The value of x was determined to be 0.66 and 0.53 for the methanol/ethylene glycol mixtures and alcohols, respectively. The absorption and FL emission spectra of the aMR-incorporated vinyl polymers were almost similar to those of aMR. The FLQYs of P(MMA-co-aMR), P(St-co-aMR), P(HEMA-co-MMA-co-aMR) films were 4.9, 4.3, and 5.1%, respectively. These FLQYs are ∼10 times of the values obtained with their solutions. As soon as the polymer film came into contact with the fluids, its FL emission started to decrease and reached an equilibrium state after a few minutes. It was found that the equilibrium FL emission became weaker as the viscosity of fluid decreased. The FL intensity ratio was also expressed using the modified Förster-Hoffmann equation. The x values of P(MMA-co-aMR) for alcohols and methanol/ethylene glycol mixtures, P(St-co-aMR) for hydrocarbons, and P(HEMA-co-MMA-co-aMR) for the methanol/ethylene glycol mixtures were 0.26, 0.24, 0.29, and 0.53 respectively.

Charge transfer induced unexpected red-shift absorption of Zn and Cu porous coordination polymers based on electron-withdrawing ligand

In the research of wide-range light-absorbing coordination polymers, to enhance intermolecular or intramolecular charge transfer (CT) and decrease the electron transition excitation energy, a dedicatedly designed novel pyridine diketopyrrolopyrrole (DPP) ligand with strong electron-withdrawing unit were introduced into the Zn, Cu and 1,4-benzenedicarboxylic acid (BDC) based coordination frameworks and porous coordination polymers DPP-Zn(BDC) and DPP-Cu(BDC) were obtained, respectively. By comparing study with physically-mixed samples DPP + Zn(BDC) and DPP + Cu(BDC), a fresh light-absorbing peak around 720 nm is observed and makes the samples exhibit a wide-range absorption in the range of 200–1400 nm and gives another experimental evidence for the research of charge transfer effect in naphthalenediimide-based metal-organic framework Zn2(NDC)2(DPNI) (J. Phys. Chem. Lett. 2013, 4, 453–458). The tremendous red-shift of absorbing onset wavelength could be ascribed to the enhanced intermolecular or intramolecular CT due to electron-withdrawing DPP ligands. At the mean time slow-photon effect is also discussed. The materials have been also characterized through powder XRD, FT-IR, SEM, XPS, solution-state spectra techniques and etc. This study underscores the importance of analyzing the extended structure for interpreting photophysical data based on the potential factors: CT, slow photon, or J-coupling. Moreover the research work might inspire the construction of light-responsive coordination polymers or metal-organic frameworks (MOFs) for charge or electron transfer.

Effect of acid gases on kinetic hydrate inhibitors

While kinetic hydrate inhibitors (KHIs) have seen increasing use in the hydrocarbon production industry as a cost effective hydrate mitigation strategy, there is still a lack of understanding concerning inhibition mechanisms and the underlying factors, which influence this. For example, little is known about the effect of gas composition even though this plays a major role, with lean acid gases presenting a particular challenge to KHIs. In this study, a Crystal Growth Inhibition (CGI) method previously developed in-house has been used to examine the effect of acidic gases on KHI performance. Using poly-n-vinylcaprolactam (PVCap) as the KHI, the effect of CO2 and H2S on different gas mixtures has been measured in detail for pressures up to ∼14.0 MPa. In addition, the effect of a low pH resulting from hydrochloric, acetic and citric acids on PVCap methane hydrate inhibition has been investigated for comparison. Based on experimental results and thermodynamic modelling, it is concluded that hydrate growth from dissolved gas – a significant factor for water miscible H2S and CO2 – does not appear to play a major role in KHI performance. Likewise, a pH reduction itself does not seem to have a notable influence. Instead, results point to changes in cage occupancy patterns/guest gas composition a function of pressure as having the greatest effect on KHI inhibition, potentially by changing the strength of polymer absorption on different hydrate crystal faces.

Designing 1,5‐Naphthyridine‐2,6‐dione‐Based Conjugated Polymers for Higher Crystallinity and Enhanced Light Absorption to Achieve 9.63% Efficiency Polymer Solar Cells

AbstractHighly crystalline conjugated polymers represent a key material for producing high‐performance thick‐active‐layer polymer solar cells (PSCs). However, despite their potential, a limited number of crystalline polymers are used in PSCs because of the lack of highly coplanar acceptor building blocks and insufficient light absorptivity (α &lt; 105) of most donor (D)–acceptor (A)‐type polymers. This study reports a series of novel 3,7‐di(thiophen‐2‐yl)‐1,5‐naphthyridine‐2,6‐dione (NTDT) acceptor‐based conjugated polymers, PNTDT‐2T, PNTDT‐TT, and PNTDT‐2F2T, synthesized with 2,2′‐bithiophene (2T), thieno[3,2‐b]thiophene (TT), and 3,3′‐difluoro‐2,2′‐bithiophene (2F2T) donor units, respectively. PNTDT‐2F2T exhibits superior polymer crystallinity and a much higher absorption coefficient than those of PNTDT‐2T or PNTDT‐TT because of adequate matching between highly coplanar A (NTDT) and D (2F2T) building blocks. A bulk heterojunction solar cell based on PNTDT‐2F2T exhibits a power conversion efficiency of up to 9.63%, with a high short circuit current of 18.80 mA cm−2 and fill factor of 0.70, when a thick active layer (&gt;200 nm) is used, without postfabrication hot processing. The findings demonstrate that the polymer crystallinity and absorption coefficient can be effectively controlled by selecting appropriate D and A building blocks, and that NTDT is a novel and versatile A building block for highly efficient thick‐active‐layer PSCs.

Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

Abstract In this paper, we investigate sulfur chemistry in laboratory analogs of Jupiter Trojans and Kuiper Belt Objects (KBOs). Electron irradiation experiments of CH3OH–NH3–H2O and H2S–CH3OH–NH3–H2O ices were conducted to better understand the chemical differences between primordial planetesimals inside and outside the sublimation line of H2S. The main goal of this work is to test the chemical plausibility of the hypothesis correlating the color bimodality in Jupiter Trojans with sulfur chemistry in the incipient solar system. Temperature programmed desorption (TPD) of the irradiated mixtures allows the detection of small sulfur allotropes (S3 and S4) after the irradiation of H2S containing ice mixtures. These small, red polymers are metastable and could polymerize further under thermal processing and irradiation, producing larger sulfur polymers (mainly S8) that are spectroscopically neutral at wavelengths above 500 nm. This transformation may affect the spectral reflectance of Jupiter Trojans in a different way compared to KBOs, thereby providing a useful framework for possibly differentiating and determining the formation and history of small bodies. Along with allotropes, we report the production of organo-sulfur molecules. Sulfur molecules produced in our experiment have been recently detected by Rosetta in the coma of 67P/Churyumov–Gerasimenko. The very weak absorption of sulfur polymers in the infrared range hampers their identification on Trojans and KBOs, but these allotropes strongly absorb light at UV and Visible wavelengths. This suggests that high signal-to-noise ratio UV–Vis spectra of these objects could provide new constraints on their presence.

Investigation of Optical Properties of Solochrome Dark Blue Dye Doped Polymer Films

The optical properties of the pure poly(methylmethcrylate) (PMMA) polymer film and PMMA polymer films doped with Solochrome Dark Blue dye at different concentrations were investigated. The films were prepared using the casting technique. The optical absorption and transmission spectra of these films were recorded in the wavelength range 300 - 900 nm for different concentrations using UV-Vis double - beam spectrophotometer. The optical parameters of the Solochrome Dark Blue dye - doped polymer films, reflectance (R), absorption coefficient (α), extinction coefficient (κ), refractive index (n), optical and electrical conductivities (σopt and σelect), and optical energy band gap (Eg), were calculated. The effect of the dye concentration on these parameters was studied. The obtained results show that the Solochrome Dark Blue dye is a promising material for applications in photonic and optoelectronic devices.

Highly absorbing multispectral near-infrared polymer nanoparticles from one conjugated backbone for photoacoustic imaging and photothermal therapy.

Semiconducting polymers with specific absorption are useful in various applications, including organic optoelectronics, optical imaging, and nanomedicine. However, the optical absorption of a semiconducting polymer with a determined structure is hardly tunable when compared with that of inorganic semiconductors. In this work, we show that the optical absorption of polymer nanoparticles from one conjugated backbone can be effectively tuned through judicious design of the particle morphology and the persistence length of polymers. Highly absorbing near-infrared (NIR) polymers based on diketopyrrolopyrrole-dithiophene (DPP-DT) are synthesized to have different molecular weights (MWs). The DPP-DT polymer with a large molecular weight and high persistence length exhibited remarkably high optical absorption with a peak mass extinction coefficient of 81.7Lg-1cm-1, which is one of the highest value among various photothermal agents reported to date. Particularly, the polymer nanoparticles with different sizes exhibit broadly tunable NIR absorption peaks from 630 to 811nm. The PEGylated small polymer dots (Pdots) show good NIR light-harvesting efficiency and high non-radiative decay rates, resulting in a relatively high photothermal conversion efficiency in excess of 50%. Thus, this Pdot-based platform can serve as promising photothermal agents and photoacoustic probes for cancer theranostics.

Multi-scale modelling of heat transfer in polyurethane foams

The influence of morphology and cell gas composition on heat insulation properties of polyurethane (PU) foams was investigated using a multi-scale mathematical model. The polymer absorption coefficient was determined from quantum chemical computations. Reverse non-equilibrium molecular dynamics was used to calculate the thermal conductivity of polymer and gas mixtures relevant to PU foams. The equivalent foam conductivity was calculated using homogeneous phase approach. The individual models were coupled together using suitable surrogate models within MoDeNa framework. To validate the proposed model 9 foam samples were prepared using different recipes, their morphology was characterized and their thermal conductivity was measured. The difference between experimental and predicted values was comparable to experimental error. Developed multi-scale model was used to identify the most suitable relation for the calculation of thermal conductivity of gas mixtures in PU foams and to quantify the influence of foam density, cell size, and strut content on heat insulation properties of PU foams.