Corrigendum: Focused laser-induced marangoni dewetting for patterning polymer thin films (original) (raw)
Determining the phase behavior of nanoparticle-filled binary blends
Journal of Polymer Science Part B: Polymer Physics, 2006
Nanoparticle additives provide a means of imparting the desired electrical, optical, or mechanical properties to a polymeric matrix. The difficulty faced in creating these composites is determining the optimal conditions for forming a thermodynamically stable mixture, where the particles will not phase separate from the matrix material. This challenge is even more daunting when the polymeric matrix is itself a multicomponent mixture, as is often the case in advanced materials. Ideally, the nanoparticles would not only con-tribute the needed physical properties, but also stabilize the mixture so that the entire system forms a single-phase system. In this study, we use a free energy expression for a binary blend that contains nanoparticles and take the interaction parameters between the different species to be independent variables. Thus, the particles can have distinct enthalpic interactions with each of the polymeric components. Using this expression, we determine the conditions under which the mixture forms a stable, single-phase material. In particular, we isolate how variations in the system's parameters (e.g., polymer composition, particle volume fraction, particle size, interaction energies) affect the phase diagrams. The findings provide guidelines for creating effective formulations and can allow researchers to understand how choices made in the nature of the components affect the overall macroscopic properties.
Electrospinning of ultrahigh-molecular-weight polyethylene nanofibers
Journal of Polymer Science Part B: Polymer Physics, 2007
The electrospinning method has been employed to fabricate ultrafine nanofibers of ultrahigh-molecular-weight polyethylene for the first time with a mixture of solvents of different dielectric constants and conductivities. The possibility of producing highly oriented nanofibers from ultrahigh-molecular-weight polymers suggests new ways of fabricating ultrastrong, porous, and single-component nanocomposite fibers with improved properties. V
Journal of Polymer Science Part B: Polymer Physics, 2010
Polypropylene/ethylene-co-vinyl acetate (PP/EVA) nanocomposites with functionalized multiwalled carbon nanotubes (FMWCNTs) have been prepared. The dissolution experiment, transmission electronic microscope, and scanning electronic microscope characterizations prove that, in the nanocomposites with sea-island morphology, although some FMWCNTs are observed in both PP and EVA phases, most of FMWCNTs distribute at the interface; however, in the nanocomposites with cocontinuous morphology, FMWCNTs mainly distribute in EVA phase. Further results based on (differential scanning calorimetry) measurements show that the different dis-persion states of FMWCNTs, which are resulted by the different melt blending sequences, result in the different crystallization behaviors of PP matrix. The mechanical measurements show that FMWCNTs exhibit apparent reinforcement and toughening effects for immiscible PP/EVA blends, and such effects are greatly dependent upon the blending sequences.
Journal of Polymer Science Part B: Polymer Physics, 2007
Mechanical, thermal, and electrical properties of graphite/PMMA composites have been evaluated as functions of particle size and dispersion of the graphitic nanofiller components via the use of three different graphitic nanofillers: ''as received graphite'' (ARG), ''expanded graphite,'' (EG) and ''graphite nanoplatelets'' (GNPs) EG, a graphitic materials with much lower density than ARG, was prepared from ARG flakes via an acid intercalation and thermal expansion. Subsequent sonication of EG in a liquid yielded GNPs as thin stacks of graphitic platelets with thicknesses of $10 nm. Solution-based processing was used to prepare PMMA composites with these three fillers. Dynamic mechanical analysis, thermal analysis, and electrical impedance measurements were carried out on the resulting composites, demonstrating that reduced particle size, high surface area, and increased surface roughness can significantly alter the graphite/polymer interface and enhance the mechanical, thermal, and electrical properties of the polymer matrix.
Phase equilibrium and charge fractionation in polyelectrolyte solutions
Journal of Polymer Science Part B-polymer Physics, 2007
A new type of phase separation in the polyelectrolyte solutions consisting of several types of charged macromolecules differing in their degree of ionization is presented. Via a general thermodynamic consideration we show that even a small difference in the degree of ionization of otherwise equivalent high-molecular components results in their spatial separation occurring upon decreasing the temperature much earlier than precipitation of any of the pure components from the solution. Some implications of charge fractionation are discussed, including the separation of DNA (or RNA) strands interacting with different proteins and the appearance of heterogeneities in polyelectrolyte solutions of partially charged hydrophobic chains with polydispersed charge distributions such as sodium polystyrene sulfonate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3003–3009, 2007
Thermodynamic characterization of poly(2,2,3,3,3-pentafluoropropyl methacrylate
Journal of Polymer Science Part B-polymer Physics, 2010
The thermodynamic characterization of a fluorinated methacrylic homopolymer was conducted by means of inverse gas chromatography (IGC), at infinite dilution. The homopolymer under study, poly(2,2,3,3,3-pentafluoropropyl methacrylate) (PPFPMA), was synthesized via a free radical polymerization reaction and was characterized by the employment of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and size exclusion chromatography (SEC) techniques. The specific retention volume of 15 solvents, used as probes, was used for the assessment of the Flory–Huggins interaction parameter, the weight fraction activity coefficient, the molar heat, energy and entropy of sorption, the partial heat of mixing of the probes, as well as the solubility parameter of the polymer. The results demonstrate that PPFPMA is insoluble in most organic solvents even at increased temperatures, with the exception of solvents like 2-Butanone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1826–1833, 2010
Relaxation processes in PVAc-HA nanocomposites
Journal of Polymer Science Part B-polymer Physics, 2007
Fundamental principles of polymer physics were used for description of relaxation behavior of polymer chain near solid surface. In a nanocomposite, considerable portion of polymer matrix is in contact with the filler surface even at very low filler loadings. In this study, nanocomposite was considered as a two component system consisting of (i) bulk polymer matrix and (ii) effective particles composed of adsorbed polymer shell and filler particle core. Both polymer phases, i.e., bulk and immobilized, are able to relax, however, each of them on a different time scale. Thus, above the neat matrix T g , these two phases undergo (i) free and (ii) retarded reptation dynamics due to the adsorption processes on the filler surface, respectively. Relaxation time was calculated for each phase using the reptation theory. To calculate the mixed response of the whole polymer nanocomposite, a simple rule of mixtures model and percolation model were used. Calculated composite relaxation times were correlated with experimental modulus recovery data measured after the Payne effect in poly(vinylacetate)-hydroxyapatite nanocomposite. Good agreement was found between theoretical predictions and experimental data.
Mathematical modeling of crystallization analysis fractionation (Crystaf) of polyethylene
Journal of Polymer Science Part B: Polymer Physics, 2006
Four polyethylene samples (PE) with different molecular weight distributions (MWD) were analyzed by crystallization analysis fractionation (Crystaf) at several cooling rates to investigate the effect of MWD and cooling rate on their Crystaf profiles. Using these results, we developed a mathematical model for Crystaf that considers crystallization kinetic effects, which are ignored in all previous Crystaf models. The Crystaf model we proposed can fit the experimental Crystaf profiles of the 4 polyethylene resins very well.
Prediction of yield and long-term failure of oriented polypropylene: Kinetics and anisotropy
Journal of Polymer Science Part B: Polymer Physics, 2009
The time-dependent yield and failure behavior of off-axis loaded uniaxially oriented polypropylene tape is investigated. The yield and failure behavior is described with an anisotropic viscoplastic model. A viscoplastic flow rule is used with an equivalent stress, based on Hill's anisotropic yield criterion, and the Eyring flow theory combined with a critical equivalent strain definition. This model is based on factorization of the rate and draw ratio dependence and is capable of quantitatively predicting the rate, angle and draw ratio dependence of the yield stress as well as time-to-failure in various off-axis tensile loading conditions characterized solely from the transverse direction.
Journal of Polymer Science Part B: Polymer Physics, 2008
The charge transport properties in a series of electroluminescent biphenylyl substituted PPV derivatives, poly[(2-(3 0 -(p-2 00 -ethylhexyloxyphenyl)phenyl)-1,4phenylenevinylene) (MP-PPV), poly[2-(2 0 -phenyl-4 0 ,5 0 -bis(3 00 -methylbutoxy))phenyl-1,4phenylene vinylene] (BP-PPV) and poly{[2-(4 0 ,5 0 -bis(3 00 -methylbutoxy)-2 0 -phenyl)phenyl-1,4-phenylene-vinylene]-co-(9,9-dioctyl-2,7-fluorenylene-vinylene)} (BPPPV-PF), have been studied using a time of flight (TOF) photoconductivity technique. The TOF transients for holes in these polymers were weakly dispersive in nature with a mobility of the order of $10 À5 cm 2 /V s at room temperature. The temperature and field dependence of charge mobility has been studied and analyzed using the disorder formalisms (Bä ssler's Gaussian disorder model (GDM) and correlated disorder model (CDM)). The charge transport parameters, such as mobility prefactor, energetic disorder, positional disorder, and the average intersite distance, were estimated from the fit and correlated to the molecular structure of the polymer. The microscopic charge transport parameters derived for these polymers indicate that these biphenylyl substituted PPV derivatives have very good chemical purity and structural regularity, which is similar to the reported values for structurally related fully conjugated polymers with high chemical purity.