Tracer-Diffusion in Weakly-Ordered Block Copolymers

1989 ◽  
Vol 177 ◽  
Author(s):  
Glenn H. Fredrickson ◽  
Scott T. Milner
Keyword(s):  
Molecular Weight ◽  
Chemical Potential ◽  
Tracer Diffusion ◽  
The Self ◽  
Lamellar Phase ◽  
Radius Of Gyration ◽  
Tracer Diffusion Coefficient ◽  
Spatially Periodic ◽  
Different Molecular Weight ◽  
Diffusion Properties

ABSTRACTWe have investigated the self and tracer-diffusion properties of a labeled diblock copolymer in a weakly-ordered lamellar phase. This phase can be a pure copolymer of equal or different molecular weight, or might contain added homopolymer. The spatially-periodic chemical potential field presented by the lamellar phase is capable of strongly influencing the diffusive motion of the tracer. In general, this field serves to slow diffusion, although the manner in which it acts depends on the wavelength of the potential relative to the labeled copolymer radius-of-gyration and on the composition of the copolymer. In the extreme limit of compositional asymmetry of the diblock tracer, we obtain results for the tracer-diffusion coefficient of a homopolymer.

Temperature dependence of tracer diffusion coefficients in polystyrene

1986 ◽  
Vol 1 (1) ◽  
pp. 202-204 ◽  
Author(s):  
Peter F. Green ◽  
Edward J. Kramer
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Shear Rate ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Tracer Diffusion Coefficient ◽  
Critical Molecular Weight ◽  
Tracer Diffusion Coefficients ◽  
Monomeric Friction Coefficient

The temperature dependence of the tracer diffusion coefficient D* of long deuterated polystyrene (d-PS) chains of molecular weight M>Mc, where Mc is the critical molecular weight for entanglement, diffusing into highly entangled PS matrices, each of molecular weight P = 2×107, is studied using forward recoil spectrometry. It is found that the temperature dependence of D*/T, reflected primarily in the monomeric friction coefficient, is accurately described by a Vogel equation. The constants that are used to fit these results are independent of M and are the same as those used to fit the temperature dependence of the zero shear rate viscosity of polystyrene.

scholarly journals The tracer diffusion coefficient of soft nanoparticles in a linear polymer matrix

RSC Advances ◽  
2017 ◽  
Vol 7 (25) ◽  
pp. 15574-15581 ◽  
Author(s):  
Adam E. Imel ◽  
Sahar Rostom ◽  
Wade Holley ◽  
Durairaj Baskaran ◽  
J. W. Mays ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Polymer Nanocomposites ◽  
Polymer Matrix ◽  
Tracer Diffusion ◽  
Linear Polymer ◽  
Tracer Diffusion Coefficient ◽  
Soft Nanoparticles ◽  
Diffusion Properties

The diffusion properties of nanoparticles in polymer nanocomposites are largely unknown and are often difficult to determine experimentally.

The Reactive Formation of Diblock Copolymer at a Polymer/Polymer Interface and its Effect on Interfacial Structure

2000 ◽  
Vol 629 ◽  
Author(s):  
Jonathan S. Schulze ◽  
Timothy P. Lodge ◽  
Christopher W. Macosko
Keyword(s):  
Molecular Weight ◽  
Interfacial Structure ◽  
Root Mean Square Roughness ◽  
Radius Of Gyration ◽  
Interfacial Region ◽  
Force Microscopy ◽  
Amino Terminal ◽  
Polymer Interface ◽  
Atomic Force ◽  
Time Required

ABSTRACTThe reaction of perdeuterated amino-terminal polystyrene (dPS-NH2) with anhydrideterminal poly(methyl methacrylate) (PMMA-anh) at a PS/PMMA interface has been observed with forward recoil spectrometry (FRES). Bilayer samples were constructed by placing thin films of PS containing ∼8.5 wt % dPS-NH2 on a PMMA-anh layer. Significant reaction was observed only after annealing the samples at 174°C for several hours, a time scale at least two orders of magnitude greater than the time required for the dPS-NH2 chains to diffuse through the bulk PS layer. The topography of the interfacial region as copolymer formed was measured using atomic force microscopy (AFM). Roughening of the PS/PMMA interface was observed to varying degrees in all annealed samples. Furthermore, the extent of this roughening was found to depend on the PS matrix molecular weight. Reaction in the samples with a high molecular weight PS matrix resulted in a root mean square roughness approximately equal to the radius of gyration Rg of the copolymer. However, approximately twice as much roughening was observed in the low molecular weight PS matrix. This study reveals how the molecular weight of one of the phases can affect the rate of reaction at a polymer/polymer interface.

Quantities Directly Measurable by Scattering

2018 ◽  
Author(s):  
Eaton E. Lattman ◽  
Thomas D. Grant ◽  
Edward H. Snell
Keyword(s):  
Molecular Weight ◽  
Particle Shape ◽  
Particle Surface ◽  
Scattering Data ◽  
Radius Of Gyration ◽  
Particle Volume ◽  
Particle Surface Area ◽  
Scattering Angle ◽  
Particle Dimension ◽  
Maximum Particle

In this chapter we note that solution scattering data can be divided into four regions. At zero scattering angle, the scattering provides information on molecular weight of the particle in solution. Beyond that, the scattering is influenced by the radius of gyration. As the scattering angle increases, the scattering is influenced by the particle shape, and finally by the interface with the particle and the solution. There are a number of important invariants that can be calculated directly from the data including molecular mass, radius of gyration, Porod invariant, particle volume, maximum particle dimension, particle surface area, correlation length, and volume of correlation. The meaning of these is described in turn along with their mathematical derivations.

scholarly journals Nano-Assemblies from Amphiphilic PnBA-b-POEGA Copolymers as Drug Nanocarriers

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1164
Author(s):  
Angeliki Chroni ◽  
Thomas Mavromoustakos ◽  
Stergios Pispas
Keyword(s):  
Molecular Weight ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Polymeric Nanocarriers ◽  
Reversible Addition ◽  
2D Noesy ◽  
Drug Nanocarriers ◽  
Glycol Methyl Ether ◽  
Different Molecular Weight

The focus of this study is the development of highly stable losartan potassium (LSR) polymeric nanocarriers. Two novel amphiphilic poly(n-butyl acrylate)-block-poly(oligo(ethylene glycol) methyl ether acrylate) (PnBA-b-POEGA) copolymers with different molecular weight (Mw) of PnBA are synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization, followed by the encapsulation of LSR into both PnBA-b-POEGA micelles. Based on dynamic light scattering (DLS), the PnBA30-b-POEGA70 and PnBA27-b-POEGA73 (where the subscripts denote wt.% composition of the components) copolymers formed micelles of 10 nm and 24 nm in water. The LSR-loaded PnBA-b-POEGA nanocarriers presented increased size and greater mass nanostructures compared to empty micelles, implying the successful loading of LSR into the inner hydrophobic domains. A thorough NMR (nuclear magnetic resonance) characterization of the LSR-loaded PnBA-b-POEGA nanocarriers was conducted. Strong intermolecular interactions between the biphenyl ring and the butyl chain of LSR with the methylene signals of PnBA were evidenced by 2D-NOESY experiments. The highest hydrophobicity of the PnBA27-b-POEGA73 micelles contributed to an efficient encapsulation of LSR into the micelles exhibiting a greater value of %EE compared to PnBA30-b-POEGA70 + 50% LSR nanocarriers. Ultrasound release profiles of LSR signified that a great amount of the encapsulated LSR is strongly attached to both PnBA30-b-POEGA70 and PnBA27-b-POEGA73 micelles.

Study of Solid Polyurethane Electrolytes Synthesized from HDI and PEO of Different Molecular Weight

2021 ◽  
pp. 115305
Author(s):  
Qian Zhang ◽  
Yuhao Wen ◽  
Kang Liu ◽  
Nailiang Liu ◽  
Yaping Du ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Different Molecular Weight

scholarly journals Self-Stable Precipitation Polymerization Molecular Entanglement Effect and Molecular Weight Simulations and Experiments

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2243
Author(s):  
Jiali Qu ◽  
Yi Gao ◽  
Wantai Yang
Keyword(s):  
Molecular Weight ◽  
Maleic Anhydride ◽  
Molecular Conformation ◽  
Average Molecular Weight ◽  
Precipitation Polymerization ◽  
Radius Of Gyration ◽  
Propagation Mechanism ◽  
Reactive Molecular Dynamics ◽  
End Distance ◽  
Good Agreement

In this paper, we developed a reactive molecular dynamics (RMD) scheme to simulate the Self-Stable Precipitation (SP) polymerization of 1-pentene and cyclopentene (C5) with maleic anhydride (MAn) in an all-atom resolution. We studied the chain propagation mechanism by tracking the changes in molecular conformation and analyzing end-to-end distance and radius of gyration. The results show that the main reason of chain termination in the reaction process was due to intramolecular cyclic entanglement, which made the active center wrapped in the center of the globular chain. After conducting the experiment in the same condition with the simulation, we found that the distribution trend and peak value of the molecular-weight-distribution curve in the simulation were consistent with experimental results. The simulated number average molecular weight (Mn) and weight average molecular weight (Mw) were in good agreement with the experiment. Moreover, the simulated molecular polydispersity index (PDI) for cyclopentene reaction with maleic anhydride was accurate, differing by 0.04 from the experimental value. These show that this model is suitable for C5–maleic anhydride self-stable precipitation polymerization and is expected to be used as a molecular weight prediction tool for other maleic anhydride self-stable precipitation polymerization system.

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