pinecone/core-2020-05-10-deduplication huggingface dataset:
Transformation of sulfur to organic-inorganic hybrids employed by networks and their application for the modulation of refractive indices

In this manuscript, we present the hybrid materials with sulfur as an inorganic element. Initially, the network polymers with the polysulfide-bridged polyhedral oligomeric silsesquioxane were synthesized and mixed with polystyrene and poly(methyl methacrylate). The resulting polymer blends showed higher thermal degradation temperatures than that of the polymer matrix similarly as typical hybrids. Next, it was found that the sulfur-bridging networks can increase refractive indices of the polymer matrices. Moreover, it was revealed that the loss of Abbe numbers was hardly observed by blending to conventional polymers
The pH-induced vesicle-to-micelle morphology transition of a THP-protected polymer

This is the peer reviewed version of the following article: DONCOM, K., WILLCOCK, H. and O'REILLY, K., 2014. The pH-induced vesicle-to-micelle morphology transition of a THP-protected polymer. Journal of Polymer Science. Part A, Polymer Chemistry, 52 (21), pp.3026-3031, which has been published in final form at: http://dx.doi.org/10.1002/pola.27348. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.A diblock copolymer consisting of tetrahydropyranyl acrylate (THPA) as a pH-deprotectable block, and a permanently hydrophobic block, methyl acrylate, was synthesized by RAFT polymerization using a quaternary amine functionalized, hydrophilic, RAFT chain transfer agent. The polymer self-assembled in water to form vesicles with Dh = 130 nm, as determined by DLS and cryogenic transmission electron microscopy. Acid catalyzed deprotection of the THPA units to yield acrylic acid resulted in a vesicle to micelle morphology transition, as evidenced by the decrease in hydrodynamic diameter to Dh = 19 nm and the observation of micelles by dry state transmission electron microscopy
Preparation, properties, and antibacterial behavior of a novel cellulose derivative containing lactam groups.

Lactam groups were introduced onto the backbone of hydroxyethyl cellulose (HEC) to modify properties, such as solubility in organic solvents and solution viscosity and to introduce possible antibacterial activity. Functionalization was achieved using 1-(hydroxymethyl)-2-pyrrolidinone (HMP), and the functionalization reactions were investigated using NMR spectroscopy. The covalent attachment between HEC and HMP was confirmed using 1H-13C correlated NMR experiments. Degrees of functionalization were calculated using integrated 13C NMR spectra, with values of up to 0.9 being demonstrated on the primary alcohol functionality of HEC. The functionalized HECs showed markedly different properties to unfunctionalized HEC, including the ability to swell considerably in water. Functionalized HEC displayed increased thermal stability and reduced solution viscosity compared with unfunctionalized HEC. Moreover, functionalization altered the bacterial adhesion characteristics compared with unfunctionalized HEC
pH-Responsive Near-Infrared Emitting Conjugated Polymer Nanoparticles for Cellular Imaging and Controlled-Drug Delivery

Cataloged from PDF version of article.In this article, pH-responsive near-infrared emitting conjugated polymer nanoparticles (CPNs) are prepared, characterized, and their stabilities are investigated under various conditions. These nanoparticles have capacity to be loaded with water insoluble, anticancer drug, camptothecin (CPT), with around 10% drug loading efficiency. The in vitro release studies demonstrate that the release of CPTs from CPNs is pH-dependent such that significantly faster drug release at mildly acidic pH of 5.0 compared with physiological pH 7.4 is observed. Time and dose-dependent in vitro cytotoxicity tests of blank and CPT-loaded nanoparticles are performed by real-time cell electronic sensing (RT-CES) assay with hepatocellular carcinoma cells (Huh7). The results indicate that CPNs can be effectively utilized as vehicles for pH-triggered release of anticancer drugs. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 114-12
A Facile Method for the Stain-Free Visualization of Hierarchical Structures with Electron Microscopy

Diblock copolymers form hierarchical morphologies with numerous applications in drug delivery and as nanoreactors. Yet, the visualization of these structures by electron microscopy can be extremely difficult, requiring complex staining techniques with associated health risks and the potential to alter structural morphology. Reported here is the synthesis of diblock copolymers by RAFT containing 3,5-bis(trifluoromethyl)phenyl functionality allowing for facile visualization of their resulting hierarchical structures by TEM with no further sample preparation.P.E.W. thanks the AWE and E.A. thanks Schlumberger for financial support,
and J.d.B is grateful for a Marie Curie Intraeuropean Fellowship
(project # 273807). This work was also supported by an ERC Starting
Investigator Grant (ASPiRe) and a Next Generation Fellowship provided
by the Walters-Kundert Foundation.This is the accepted manuscript. The final published version is available from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/pola.27517/abstract
Energy transfer through heterogeneous dyes-substituted fluorene-containing alternating copolymers and their dual-emission properties in the films

We report synthesis of the modified fluorene polymers tethered to the heterogeneous types of the fluorescent dyes at the cardo carbon for obtaining the dual-emissive solid materials. A series of the alternating fluorene copolymers modified with pyrene or 9, 10-diphenylanthracene and BODIPY at the cardo carbon based on the red-emissive donor–acceptor structure were prepared, and their characteristics were examined. From the measurements of the optical properties, the energy transfer efficiencies were evaluated. In summary, variable energy transfer efficiencies were observed between the side chains and from the side chain to the main chain. It was indicated that the energy transfer efficiencies were strongly depended on the types of the energy donor and the detection conditions as such in the solution or film. Furthermore, it was found that the cardo fluorene units can contribute to the suppression of the energy transfer in the condensed state. Finally, the dual-emissive polymers were obtained in the film states. This is the first example, to the best of our knowledge, not only to offer systematic information on the energy transfer between the dye molecules and the polymer main-chains via the cardo structure but also to demonstrate the polymer-based optical materials with the dual-emission properties
Efficient water-soluble drag reducing star polymers with improved mechanical stability.

We describe here the first example of the synthesis of 4-arm star poly(acrylic acid) for use as a water-soluble drag reducing agent, by applying Cu(0)-mediated polymerization technique. High molecular weight 4-arm star poly(tert-butyl acrylate) (Mn = 3.0–9.0 × 105 g mol−1) was first synthesized using 4,4′-oxybis(3,3-bis(2-bromopropionate)butane as an initiator and a simple Cu(0)/TREN catalyst system. Then, 4-arm star poly(tert-butyl acrylate) were subjected to hydrolysis using trifluoroacetic acid resulting in water-soluble 4-arm star poly(acrylic acid). Drag reduction test rig analysis showed 4-arm star poly(acrylic acid) to be effective as a drag reducing agent with drag reduction of 24.3%. Moreover, 4-arm star poly(acrylic acid) exhibited superior mechanical stability when compared with a linear poly(acrylic acid) and commercially available drag reducing polymers; Praestol and poly(ethylene oxide). The linear poly(acrylic acid), Praestol, and poly(ethylene oxide) all showed a large decrease in drag reduction of 8–12% when cycled 30 times through the drag reduction test rig while, in contrast, 4-arm star poly(acrylic acid) demonstrated much higher mechanical stability
α-exomethylene lactone possessing acetal–ester linkage: Polymerization and postpolymerization modification for water-soluble polymer

First published: 16 October 20152,6-Dimethyl-5-methylene-1,3-dioxa-4-one (DMDO), a cyclic acrylate possessing acetal–ester linkage, was obtained as a mixture of cis- and trans-isomers (95:5) from Baylis–Hillman reaction of an aryl acrylate. The radical and anionic polymerizations of DMDO yielded the corresponding vinyl polymers without any side reactions such as cleavage of the acetal–ester linkage. The polymerization behaviors were significantly different from that of the acyclic acrylate, α-(hydroxymethyl)acrylic acid, which was expected inactive against polymerization due to the steric hindrance around the vinylidene group by the α-substituent. The acetal–ester linkage of the obtained polymer (P1) was completely cleaved via acid hydrolysis to afford a water soluble polymer, P2. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 955–96
Synthesis of conjugated polymers possessing diketopyrrolopyrrole units bearing phenyl, pyridyl, and thiazolyl groups by direct arylation polycondensation: Effects of aromatic groups in DPP on physical properties

Conjugated polymers containing phenyl-, pyridyl-, and thiazolyl-flanked diketopyrrolopyrrole (DPP) were synthesized by direct arylation polycondensation of 3,4-ethylenedioxythiophene derivatives and dibrominated DPP-based monomers, in order to probe the effects of the aromatic groups in the DPP units on the absorption property, energy level, and crystallinity. A polymer possessing thiazolyl-flanked DPP units was found to display long-wavelength absorption properties and higher crystallinity than the polymers bearing phenyl- and pyridyl-flanked DPP units. These features of the thiazolyl-based polymer were afforded by its coplanar structure of the main chain. The synthesized polymers showed semiconducting properties in organic field effect transistors and organic photovoltaics. Direct arylation polycondensation is an efficient synthetic method that affords a series of DPP-based polymers in a simple fashion and, thus, helping in a comprehensive understanding on the relationship between the aromatic groups in DPP units and their physical properties. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2337–234
Organic-Acid Mediated Bulk Polymerization of e-Caprolactam and Its Copolymerization with e-Caprolactone

Polyamides (PA) constitute one of the most important
classes of polymeric materials and have gained strong
position in different areas, such as textiles, fibers, and construction
materials. Whereas most PA are synthesized by stepgrowth
polycondensation, PA 6 is synthesized by ring opening
polymerization (ROP) of e-caprolactam (e-CLa). The most popular
ROP methods involve the use of alkaline metal catalyst difficult
to handle at large scale. In this article, we propose the use
of organic acids for the ROP of e-CLa in bulk at 180 8C (below
the polymer’s melting point). Among evaluated organic acids,
sulfonic acids were found to be the most effective for the polymerization
of e-CLa , being the Brønsted acid ionic liquid: 1-(4-
sulfobutyl)23-methylimidazolium hydrogen sulfate the most
suitable due to its higher thermal stability. End-group analysis
by 1H nuclear magnetic resonance and model reactions provided
mechanistic insights and suggested that the catalytic
activity of sulfonic acids was a function of not only the acid
strength, but of the nucleophilic character of conjugate base as
well. Finally, the ability of sulfonic acid to promote the copolymerization
of e-CLa and e-caprolactone is demonstrated. As a
result, poly(e-caprolactam-co-e-caprolactone) copolymers with
considerably randomness are obtained. This benign route
allows the synthesis of poly(ester amide)s with different thermal
and mechanical properties.The authors acknowledge the financial support of Euskampus Fundazioa, the Spanish Ministery of Economy and Competition through project CTQ2014‐53458‐1 and the European Commission through project SUSPOL‐EJD 642671 and FP7‐PEOPLE‐212‐ITN 316832‐OLIMPIA (D. Mantione). Haritz Sardon gratefully acknowledges financial support from MINECO through project FDI 16507. A. Sanchez‐Sanchez thanks “Convocatoria de Contratación para la especialización de personal investigador doctor en la UPV/EHU” for financial support. The SGIKER UPV/EHU for the NMR facilities of Gipuzkoa campus are acknowledged
Fluorene-containing tetraphenylethylene molecules as lasing materials

A series of star-shaped oligofluorene molecules, each containing a TPE core, have been specifically designed and produced to show effective aggregation-induced emission (AIE). Each molecule differs either in the number of fluorene units within the arms (e.g., 1 or 4, compounds 4 and 5), or the terminal group positioned at the end of each arm (e.g., H, TMS, or TPA, compounds 4, 6, and 7). Although they are all poor emitters in solution phase they become efficient yellow-green luminogens in the condensed state. Their AIE properties were investigated in THF/H2O mixtures, with each molecule exhibiting a clear emission enhancement at specific water contents. An all-organic distributed feedback (DFB) laser was fabricated using compound 4 as the gain material and exhibited an average threshold energy fluence of 60 ± 6 μJ/cm2 and emission in the green region. Furthermore, piezofluorochromism studies on a thin film of this material displayed a linear dependence of the amplified spontaneous emission (ASE) peak position on applied pressure, indicating potential applications as lasing-based pressure sensors
Induction of Helical Structure by Sesamin, and Production of Oriented Helical Polymer with Liquid Crystal Magneto-Electrochemical Polymerization

Sesamin was employed as a chiral dopant for preparing cholesteric liquid crystals with right-handed helical architecture. Helical twisting power of sesamin is to be 13.4 μm−1. Electrochemical polymerizations were carried out with sesamin-induced cholesteric liquid crystal electrolyte solution for obtaining conjugated polymer films with helical structure. The film was transcribed the helical order from the liquid crystal electrolyte solution with helical structure produced by sesamin during the polymerization process. The helical axes of the macromolecular superstructure of the polymer films were oriented in a magnetic field of 4.5 T. This results demonstrated liquid crystal magneto-electrochemical polymerization with helical structure induced by sesamin as a natural chiral compound. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1894–189
Chemical warfare simulant-responsive polymer nanocomposites: Synthesis and evaluation

Nanomaterials that undergo a physical change upon chemical warfare agent (CWA) exposure can potentially be used in detectors to warn soldiers of their presence or in fabrics to provide on‐demand protection. In this study, hybrid nanoparticles (NPs) were prepared by grafting a CWA‐responsive polymer from a silicon dioxide (SiO₂) surface using ring opening metathesis polymerization; the covalent functionalization of the polymers on the NP surface was confirmed by gel permeation chromatography, dynamic light scattering, and transmission electron microscopy analysis. The polymer‐grafted SiO₂ NPs were found to undergo a pronounced decrease (approximately 200 nm) in their hydrodynamic radius upon exposure to CWA simulants trifluoroacetic acid and diethyl chlorophosphate in toluene. This decrease in hydrodynamic radius is attributed to the electrophile‐mediated ionization of the triarylmethanol responsive unit and represents a rare example of polycation formation leading to polymer chain collapse. We have ascribed this ionization‐induced collapse to the formation of a favorable stacking interaction between the planar triarylcations. These studies have important implications for the development of breathable fabrics that can provide on‐demand protection for soldiers in combat situations. Keywords: nanocomposites; stimuli-responsive; ROMP; organophosphates; triarylmethanolsDefense Threat Reduction Agency (DTRA) (Contract BA12PHM123
Normal-stress differences and the detection of disclinations in nematic elastomers

We use a continuum model to investigate the isochoric radial expansion of a right circular cylindrical specimen composed of a nematic elastomer that is cross-linked in a uniaxial state and then annealed. Numerical solutions show that, above a certain radial expansion, the material has a definitive energetic preference for a state involving a disclination of strength +1 along the cylinder axis. Surrounding such a disclination is a core with radial dimension on the order of 10^-2 ??m, which coincides with observations in conventional liquid-crystal melts. Examination of the normal-stress differences shows that the first of these differences depends non-monotonically on the extent of radial expansion and possesses a local minimum at the point where a disclination becomes energetically preferred. This suggests a practical experimental method for testing the predictions of our model.published or submitted for publicationis peer reviewe
Dynamic mechanical thermal analysis transitions of partially and fully substituted cellulose fatty esters

The main transitions of cellulose fatty esters with different degrees of substitution (DSs) were investigated with dynamic mechanical thermal analysis. Two distinct main relaxations were observed in partially substituted cellulose esters (PSCEs). They were attributed to the glass‐transition temperature and to the chain local motion of the aliphatic substituents. The temperatures of both transitions decreased when DS or the number of carbon atoms (n) of the acyl substituent increased. Conversely, all the transitions of fully substituted cellulose esters occurred within a narrow temperature range, and they did not vary significantly with n. This phenomenon was explained by the formation of a crystalline phase of the fatty substituents. The presence of few residual OH groups in PSCEs was responsible for a large increase in the storage bending modulus, and it eliminated the effect of n on damping
A model for anomalous moisture diffusion through a polymer-clay
  nanocomposite

Experimental data are reported on moisture diffusion and the elastoplastic
response of an intercalated nanocomposite with vinyl ester resin matrix and
montmorillonite clay filler at room temperature. Observations in diffusion
tests show that water transport in the neat resin is Fickian, whereas it
becomes anomalous (non-Fickian) with the growth of the clay content. This
transition is attributed to immobilization of penetrant molecules on the
surfaces of hydrophilic clay layers. Observations in uniaxial tensile tests
demonstrate that the response of vinyl ester resin is strongly elastoplastic,
whereas an increase in the clay content results in a severe decrease of plastic
strains observed as a noticeable reduction of curvatures of the stress--strain
diagrams. This is explained by slowing down of molecular mobility in the host
matrix driven by confinement of chains in galleries between platelets.
Constitutive equations are developed for the anomalous moisture diffusion
through and the elastoplastic behavior of a nanocomposite. Adjustable
parameters in these relations are found by fitting the experimental data. Fair
agreement is demonstrated between the observations and the results of numerical
simulation. A striking similarity is revealed between changes in diffusivity,
ultimate water uptake and the rate of plastic flow with an increase in the clay
content.Comment: 29 pages, 17 figure
The effect of annealing on the elastoplastic and viscoelastic responses
  of isotactic polypropylene

Observations are reported on isotactic polypropylene (i) in a series of
tensile tests with a constant strain rate on specimens annealed for 24 h at
various temperatures in the range from 110 to 150 C and (ii) in two series of
creep tests in the sub-yield region of deformation on samples not subjected to
thermal treatment and on specimens annealed at 140 C. A model is developed for
the elastoplastic and nonlinear viscoelastic responses of semicrystalline
polymers. A polymer is treated an equivalent transient network of
macromolecules bridged by junctions (physical cross-links, entanglements and
lamellar blocks). The network is assumed to be highly heterogeneous, and it is
thought of as an ensemble of meso-regions with different activation energies
for separation of strands from temporary nodes. The elastoplastic behavior is
modelled as sliding of meso-domains with respect to each other driven by
mechanical factors. The viscoelastic response is attributed to detachment of
active strands from temporary junctions and attachment of dangling chains to
the network. Constitutive equations for isothermal uniaxial deformation are
derived by using the laws of thermodynamics. Adjustable parameters in the
stress-strain relations are found by fitting the experimental data.Comment: 29 pages, 14 figure
Onsager consistency checks for multicomponent diffusion models

The Onsager reciprocity relations are applied to several recently proposed multicomponent diffusion models in an attempt to gauge their validity and ascertain their applicability. Each of these friction-based diffusion models stems from the more general Bearman formalism through various assumptions regarding the individual friction coefficients. By assessing the compliance of the Bearman model with respect to the Onsager relations, we ascertain the validity of the simplifications introduced to each diffusion model and suggest which postulates lead to results consistent with the Onsager relations. Although some models are not consistent with the Onsager relations, each model predicts the multicomponent drying of polymer films reasonably well. The necessity for consistency with the Onsager development is, therefore, revisited
Physics of thick polymers

We present the results of analytic calculations and numerical simulations of
the behaviour of a new class of chain molecules which we call thick polymers.
The concept of the thickness of such a polymer, viewed as a tube, is
encapsulated by a special three body interaction and impacts on the behaviour
both locally and non-locally. When thick polymers undergo compaction due to an
attractive self-interaction, we find a new type of phase transition between a
compact phase and a swollen phase at zero temperature on increasing the
thickness. In the vicinity of this transition, short tubes form space filling
helices and sheets as observed in protein native state structures. Upon
increasing the chain length, or the number of chains, we numerically find a
crossover from secondary structure motifs to a quite distinct class of
structures akin to the semi-crystalline phase of polymers or amyloid fibers in
polypeptides.Comment: 41 pages, 20 figures. Accepted for publication in J. Pol. Sci.
Non-iterative and exact method for constraining particles in a linear
  geometry

We present a practical numerical method for evaluating the Lagrange
multipliers necessary for maintaining a constrained linear geometry of
particles in dynamical simulations. The method involves no iterations, and is
limited in accuracy only by the numerical methods for solving small systems of
linear equations. As a result of the non-iterative and exact (within numerical
accuracy) nature of the procedure there is no drift in the constrained
geometry, and the method is therefore readily applied to molecular dynamics
simulations of, e.g., rigid linear molecules or materials of non-spherical
grains. We illustrate the approach through implementation in the commonly used
second-order velocity explicit Verlet method.Comment: 12 pages, 2 figure