Bulletin of the American Physical Society
APS March Meeting 2021
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Y08: Polymer RheologyLive

Hide Abstracts 
Sponsoring Units: DPOLY Chair: Pinar Akcora, Stevens Inst of Tech 
Friday, March 19, 2021 11:30AM  11:42AM Live 
Y08.00001: Facile equilibration of fullyentangled semiflexible beadspring polymer melts Joseph Fox Dietz, Martin Kröger, Robert Hoy Equilibrating model entangled polymer melts is challenging because their longest relaxation times τ_{max} scale as (N/N_{e})^{3.4}, where N is their degree of polymerization and N_{e} is their entanglement length. The wellknown doublebridging hybrid (DBH) algorithm reduces these times to τ_{max} ∼ (N/N_{e}) by performing periodic chaintopology switching Monte Carlo (MC) moves during a molecular dynamics (MD) simulation. For semiflexible chains, however, the high energy barriers associated with these MC moves make the prefactors to this (N/N_{e}) scaling prohibitively large. Here we overcome this issue by combining DBH with the use of coresoftened pair potentials. By beginning with soft pair and bond interactions, and slowly stiffening them until they reach their final functional forms while keeping the equilibrium bond length constant, we are able to equilibrate 400Kmonomer systems with N > 20 N_{e} and chain stiffnesses all the way up to the isotropicnematic transition, using singleclusternode simulations that last no more than ∼250 hours. We use this new algorithm to develop improved expressions for KremerGrest melts' chainstiffnessdependent N_{e} and Kuhn length l_{K}. 
Friday, March 19, 2021 11:42AM  11:54AM Live 
Y08.00002: Dynamics of bottlebrush polymers in dilute solution Sarit Dutta, Charles Sing Highly branched polymers consisting of a central backbone chain hosting numerous densely grafted side chains, called bottlebrush polymers, have been widely studied for the design and manufacture of selfassembled 
Friday, March 19, 2021 11:54AM  12:06PM Live 
Y08.00003: Obtaining analytic expressions for entanglementrelated properties; does the choice of topologicalanalysis method matter? Robert Hoy, Joseph D Dietz, Martin Kröger In general, the entanglement length N_{e} measured by and consequently the plateau modulus G and tube diameter a inferred from topological analyses (TA) of simulated polymeric systems depend strongly and nontrivially on both the computational algorithm used for TA and the mathematical estimator used to extract N_{e} from the TA data. We show that the recently developed unified analytic expressions [Hoy, R.S. and Kröger, M., Phys. Rev. Lett. 2020, 124, 147801] predicting how the dimensionless quantities L_{e}/l_{K}, Gl_{k}^{3}/k_{B}T, and a/l_{K} in dense polymer melts depend on l_{K}/p, where l_{K} and p are respectively the Kuhn and packing lengths, are supported by results from a TA algorithm and N_{e}estimator [Svaneborg, C. and Everaers, R., Macromolecules 2020, 53, 1917] that are very different than the ones that were used in the development of these expressions. However, comparison of results from these two methods leads to quantitative corrections for the semiflexible (l_{K}/p > 5) regime as well as new qualitative insights into the relation between primitive path structure and entanglement in this regime. 
Friday, March 19, 2021 12:06PM  12:18PM Live 
Y08.00004: Measurement of segmental dynamics of polymer glasses in the preyield regime ENRAN XING, Trevor Bennin, Josh Ricci, Mark Ediger It has been shown that the segmental dynamics of polymer glasses are accelerated by deformation, but little is known quantitatively about the change of dynamics at a small strain. Here, we modify the photobleaching method by performing a deformation within a single optical measurement and measure the segmental dynamics in the preyield regime. The results were compared with two sets of theories. One of them is Fluidity model, which assumes that the effect of deformation on the segmental dynamics is controlled by the absolute value of strain rate. Using cyclic deformation protocols, we show that deformations with the same absolute strain rate but different peak strains affect the segmental dynamics differently. The other set are NLE, Eyring and PFVD models, all of which contain explicit relationships between the change of segmental dynamics and the stress. Here, it’s found that the acceleration of the segmental dynamics falls onto a universal curve with respect to peak strains. By comparing the curve with these models, we find that NLE model gives the best fit, which indicates its functional form of the accelerationstress relationship can describe a polymer glass in the preyield regime most closely. 
Friday, March 19, 2021 12:18PM  12:30PM Live 
Y08.00005: Construction of a highly coarsegrained model for cispolybutadiene with slipsprings for rheological properties Ludwig Schneider, Alireza Behbahani, Anastassia Rissanou, Petra Bačová, Pritam Kumar Jana, Wei Li, Manolis Doxastakis, Patrycja Polinska, Craig Burkhart, Vagelis Harmandaris, Marcus Mueller We present a method to use dynamical observables from atomist and LennardJones beads spring simulations to construct a highly coarsegrained model via a topdown parameter matching. 
Friday, March 19, 2021 12:30PM  12:42PM Live 
Y08.00006: How to measure effect of solvent and charged groups on polymer excluded volume and Kuhn length Michael Jacobs, Ryan Sayko, Andrey Dobrynin Knowledge of solvent effect on polymer excluded volume and Kuhn length is a foundation of scaling analysis of solutions of charged and neutral polymers. Here we present an approach based on scaling relationship between solution correlation length ξ≈lg^{ν}/B and number of monomers per correlation blob g for polymers with monomer projection length l. Numerical coefficient B and exponent v are determined by solvent quality for the polymer backbone, chain Kuhn length and type and strength of monomermonomer interactions at different length scales starting from solutions correlation length down to thermal blob length scales. Values of the Bparameters are obtained from a plateau of normalized specific viscosity η_{sp}(c)c^{α}/N as a function of monomer concentration c with degree of polymerization N. Exponent α=1/(13ν) describes concentration dependence of the number of monomers per correlation blob, g∼c^{α}. This approach allows one to extract excluded volume and Kuhn length as a function of fraction of charged monomers and salt concentration. We illustrate this approach on saltfree solutions of Nmethyl2vinyl pyridinium chloride random copolymers in ethylene glycol and salt solutions of sodium carboxymethyl cellulose in water. 
Friday, March 19, 2021 12:42PM  12:54PM Live 
Y08.00007: Physically Intuitive Continuum Mechanics Model for QCM Applied to Obtain the FrequencyDependent Storage and Loss Modulus of PDMS Within the Glass Transition Regime Yannic Gagnon, Justin Burton, Connie Roth Quartz crystal microbalances (QCMs) are increasingly applied as MHzrheometers to measure viscoelastic properties of films beyond the simple Sauerbrey equation relating frequency shifts to mass loading of the crystal. Much QCM modeling in the literature applies mathematical simplifications such as the small load approximation to analytically solve for frequency shifts as a function of harmonic number, which cannot be applied to situations in which the frequency shift is large. In addition, many models utilize equivalent circuit formalisms, losing their physics intuition to the sample’s material properties. We present a continuum mechanics model with no mathematical approximations that numerically solves for the viscoelastic properties of the polymer, while preserving the model’s intuitive physics formulation. By incorporating frequencydependent moduli, we are able to model polydimethylsiloxane (PDMS) films within the glass transition regime, obtaining good agreement with interpolated literature values of the rubbery and glassy plateau regimes from dynamic mechanical analysis (DMA). 
Friday, March 19, 2021 12:54PM  1:06PM Live 
Y08.00008: Dynamics and Rheology of cis1,4Polybutadiene melts through Systematic Bottomup Coarsegrained Simulations Alireza Foroozani Behbahani, Ludwig Schneider, Anastassia Rissanou, Antonis Chazirakis, Petra Bačová, Pritam Kumar Jana, Wei Li, Manolis Doxastakis, Patrycja Polinska, Craig Burkhart, Marcus Mueller, Vagelis Harmandaris Due to the broad range of time and length scales involved, the simulation of high molecular weight polymer melts is not straightforward. 
Friday, March 19, 2021 1:06PM  1:18PM Live 
Y08.00009: Dynamic adsorption influences drop and bubble formation of Polymer Surfactant Complexes Carina Martinez, Thomas Mazur, Vivek Sharma Surface tension of a freshly created interface varies due to dynamic adsorption that is intimately linked with the rate of mass transfer of surfactant from liquid subphase to the interface, and this adsorptionlimited kinetics impacts the formation of drops and bubbles. Complexation of a neutral polymer to an ionic surfactant in solution influences dynamic adsorption, surface tension and bulk rheological response. Dynamic surface tension refers to the time dependent variation in surface tension, that can be characterized using conventional methods like pendant drop analysis, Wilhelmy plate, etc. However, the conventional methods are limited in their temporal resolution. In this study, we utilize maximum bubble pressure tensiometry for the measurement of dynamic surface tension at extremely short (150 ms) timescales. We characterize the adsorption kinetics of charged surfactants as well as surfactantpolymer complexes. We characterize the pinchoff dynamics of bubbles and drops to determine the influence of shear and extensional rheology behavior as well as dynamic adsorption on foamability, emulsion formation and processability. 
Friday, March 19, 2021 1:18PM  1:30PM Live 
Y08.00010: Rheology of entangled solutions of ringlinear DNA blends Dejie Kong, Sourya Banik, Michael San Francisco, Rae M RobertsonAnderson, Charles M Schroeder, Gregory B McKenna The rheological response of ring polymers remains poorly understood, and even small amounts of linear chains can have large effects on their behavior. In this work, we use monodisperse ring DNA polymers (45 kbp, 2.9 x 10^{7} g/mol) to investigate the importance of linear chains in the rheology of ringlinear blends. Linear viscoelastic measurements have been made on ringlinear DNA solutions at various concentrations with different linear chain ratios and the responses compared to those of linear λ DNA (48.5 kbp) solutions. Because of the linear threading effects, the blends have a significantly higher zeroshear rate viscosity and a much broader rubbery regime than that of the linear polymer. Furthermore, a linear ratio of 0.5 is a threshold at which the magnitude of the plateau modulus G_{N}^{0} tends towards that of the linear counterpart. However, independent of the linear content, the power law dependences of G_{N}^{0} on total concentration for the blends are the same as that of the linear solutions. We also find that the CoxMerz rule holds for the linearring topology. 
Friday, March 19, 2021 1:30PM  1:42PM 
Y08.00011: Anomalous nonlinear rheological responses of nanocomposites: the transition to linearnonlinear dichotomy Jinying Zou, Xiaorong Wang We found an anomalous nonlinear behavior under large amplitude oscillatory shears, where the amplitude stress deviates strongly from the linear dependence of strain, while the time dependence of stress remains sinusoidal. This phenomenon is usually accompanied with the Payne effect of filled rubbers. In order to understand the molecular details regarding this unusual behavior, we examined a series of polybutadiene/tetradecane solutions filled with carbon black. Our results show that there is a previously unrecognized transition in the system as the matrix polymer concentration φ approaches and passes through a characteristic polymer concentration φ_{c}. Below φ_{c}, the system typically shows the classic nonlinearity, where storage modulus G’ decreases as strain amplitude γ_{0} increases and the resulting stress waveforms are distorted from sinusoidal waves. Above φ_{c}, the system displays an anomalous nonlinearity, where the stress responses at any given strain remain surprisingly sinusoidal regardless the drop of storage modulus G’. The critical concentration φ_{c} is about an order of magnitude greater than the entanglement polymer concentration φ_{e}. The degree of entanglement in the matrix apparently determines the occurrence of this unusual rheological event and plays a key role here. 
Friday, March 19, 2021 1:42PM  1:54PM Live 
Y08.00012: Influence of Graft Density on the Viscoelastic Properties of Polymer Grafted Nanocomposites Andrew Ehlers, Pinar Akcora, Rahmi Ozisik Molecular dynamic simulations are used to investigate the dynamics and viscoelastic properties of polymer grafted nanocomposites (PGNs). In the current study, the PGN consists of a nanoparticle with grafted highTg polymer chains in a lowTg polymer matrix. These types of PGNs have been shown to have reversible and repeatable stiffening behavior upon heating (Senses, E.; Isherwood, A.; Akcora, P. ACS Appl. Mater. Interfaces 2015, 7, 14682). The interface between the grafted and matrix polymers may influence chain dynamics and viscoelastic properties of the whole system. The influence of the graft density and graft chain stiffness on viscoelastic properties is investigated to identify the mechanism of the observed stiffening in these types of PGNs. 
Friday, March 19, 2021 1:54PM  2:06PM Live 
Y08.00013: Singlemolecule imaging of tube nonlinearities for sheared, entangled Factin chains Kaikai Zheng, Zitong Zhang, Bingyang Cao, Steve Granick A homebuilt setup for singlemolecule epifluorescence imaging under controlled rheological shear is used to accomplish singlemolecule imaging of entangled Factin solutions. We find “tube softening” at low shear rate and “tube hardening” at high shear rate. Surprisingly, “tube softening” and “tube hardening” are quantitatively related to chain alignment and chain stretching, respectively – quantities that are inaccessible using conventional ensembleaveraged methods. 
Friday, March 19, 2021 2:06PM  2:18PM Live 
Y08.00014: Shear and extensional rheology of highly entangled cyclic polymer in melts and solutions Dongjie Chen, Gregory B McKenna, Judit E Puskas, Carin A Helfer, Kristof Molnar, Gabor Kaszas, Juile A Kornfield Rheology of circular polymers remains an area of active research due to the difficulty of making ring polymers of sufficient purity free of linear contaminants. Past work has been limited to rings made in dilute solution and, consequently, have been limited to sizes of approximately 15 entanglements in the linear analog and small amounts of material being available for study. These problems have been overcome by reversible radical recombination polymerization (R^{3}P) recently developed in Puskas laboratory. R^{3}P can produce 10100g scale circular polymer which opens new avenues of research. Here we have studied poly(3,6dioxa1,8octanedithiol) (PolyDODT) and Polyisobutylene disulfide synthesized by R^{3}P of different molecular weights. Of interest is that the largest PolyDODT ring investigated to date has a molecular mass corresponding to approximately 300 entanglements in the linear counterpart. The extensional rheology behavior of cyclic PIBdisulfide and cyclic PolyDODT is compared with that of linear PIB and literature data of Polystyrene ring. Linear and nonlinear shear responses of the cyclic PIBdisulfide melts, cyclic PolyDODT melts and solutions are compared with literature results published since 1980s. 
Friday, March 19, 2021 2:18PM  2:30PM Live 
Y08.00015: Rheology and scaling of concentrated linear DNA solutions Sourya Banik, Dejie Kong, Michael San Francisco, Gregory B McKenna We have studied the flow and entanglement behavior of concentrated monodisperse linear lambda DNA, M_{W }~ 3.2x10^{7 }g/mol in solution. Dynamic tests on solutions of having concentrations from 0.47 to 3.75 mg/ml DNA in an aqueous buffer showed a rubbery plateau modulus, G_{N}^{0} that scales with concentration as C^{2.24}. Two distinct zones in the behavior of the relaxation time, τ_{D} against concentration are observed: scaling as C^{~0.88} and C^{~3.55} in low and high concentration regimes, respectively. The CoxMerz rule and the time concentration superposition were established to follow in the range of concentrations studied. The damping function was obtained for different concentrations following stress relaxation experiments. The samples showed an increase in softening with strain as concentration increases. The entanglement behavior was found to be similar to that of synthetic melts and solutions. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2021 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700