Role of Nanoscale Heterogeneity in the Mechanical Performance of Hybrid Elastomers

Silvaroli, Anthony J.; Heyl, Tyler; Chyasnavichyus, Marius; Beebe, Jeremy M.; Ahn, Dongchan; Mangold, Shane L.; Chen, Qihua; Wang, Muzhou; Shull, Kenneth R.

doi:10.1021/acs.macromol.3c00466

Cited by 5 publications

(1 citation statement)

References 46 publications

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“…The shape of the feature is influenced by the volume fraction of the dispersed phase, where a sharper peak indicates a larger volume fraction, as demonstrated by models describing scattering caused by spheres. , We note that ideally, the dispersed phase volume fraction should be equivalent to the volume fraction of MMA added (either 0.3 or 0.5). However, changes in the volume fraction can be caused by different levels of mixing, which is commonly observed in IPNs. ,, In the 30% MMA IPNs, USAXS traces exhibit a single feature, indicating the presence of one population of domain sizes (Figure a). At a curing intensity of 0.2 mW/cm 2 , the feature position appears at q = 2 × 10 –3 Å –1 .…”

Section: Resultsmentioning

confidence: 99%

In Situ Investigations of Microstructure Formation in Interpenetrating Polymer Networks

Heyl,

Beebe,

Silvaroli

et al. 2024

Macromolecules

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Interpenetrating polymer networks (IPNs) represent an effective strategy for compatibilizing immiscible polymers to enhance the mechanical properties of the final material. While it has been established that the macroscopic properties are dependent on the microstructure, it is unknown why various microstructures are formed in IPNs because the microstructure is often trapped in a nonequilibrium state. To explore this, we conducted a study to establish a relationship between polymerization kinetics and microstructure formation in polydimethylsiloxane/poly(methyl methacrylate) (PDMS/PMMA) IPNs. By manipulating the UV curing intensity, we observed three distinct morphologies: isolated PMMA-rich spheres within a PDMS matrix with a monomodal domain size distribution, spheres with a bimodal size distribution, and a clustered domain microstructure. To investigate the different phase separation mechanisms, we correlated in situ small-angle X-ray scattering (SAXS) to track microstructure formation and Fourier transform infrared spectroscopy (FT-IR) to track polymerization kinetics. Based on our findings, we propose that the monomodal sphere microstructure formed via spinodal decomposition. The positions of the domains are kinetically trapped in the PDMS network, preventing macrophase separation. Similarly, the clustered domain microstructure also arises from spinodal decomposition, but increased mobility within the PDMS matrix enables domains to aggregate after network percolation. In contrast, the bimodal spherical morphology is attributed to a combination of nucleation and growth, and spinodal decomposition. We postulate that these different mechanisms are dictated by changes in the PMMA molecular weight during polymerization. Through the examination of polymerization kinetics and microstructure formation, we have proposed multiple mechanisms that explain the microstructure formation in IPNs.

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Section: Resultsmentioning

confidence: 99%

In Situ Investigations of Microstructure Formation in Interpenetrating Polymer Networks

Heyl,

Beebe,

Silvaroli

et al. 2024

Macromolecules

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Assessing the effect of minimally invasive lipid extraction on parchment integrity by artificial ageing and integrated analytical techniques

Vermeulen,

Johns,

dePolo

et al. 2024

Polymer Degradation and Stability

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Bridging Macroscopic Diffusion and Microscopic Cavity Escape of Brownian and Active Particles in Irregular Porous Networks

Shi,

Schwartz

2024

ACS Nano

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While irregular and geometrically complex pore networks are ubiquitous in nature and industrial processes, there is no universal model describing nanoparticle transport in these environments. 3D superresolution nanoparticle tracking was employed to study the motion of passive (Brownian) and active (self-propelled) species within complex networks, and universally identified a mechanism involving successive cavity exploration and escape. In all cases, the long-time ensembleaveraged diffusion coefficient was proportional to a quantity involving the characteristic length scale and time scale associated with microscopic cavity exploration and escape (D ∼ r 2 /t trap ), where the proportionality coefficient reflected the apparent porous network connectivity. For passive nanoparticles, this coefficient was always lower than expected theoretically for a random walk, indicating reduced network accessibility. In contrast, the coefficient for active nanomotors, in the same pore spaces, aligned with the theoretical value, suggesting that active particles navigate "intelligently" in porous environments, consistent with kinetic Monte Carlo simulations in networks with variable pore sizes. These findings elucidate a model of successive cavity exploration and escape for nanoparticle transport in porous networks, where pore accessibility is a function of motive force, providing insights relevant to applications in filtration, controlled release, and beyond.

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Role of Nanoscale Heterogeneity in the Mechanical Performance of Hybrid Elastomers

Cited by 5 publications

References 46 publications

In Situ Investigations of Microstructure Formation in Interpenetrating Polymer Networks

In Situ Investigations of Microstructure Formation in Interpenetrating Polymer Networks

Assessing the effect of minimally invasive lipid extraction on parchment integrity by artificial ageing and integrated analytical techniques

Bridging Macroscopic Diffusion and Microscopic Cavity Escape of Brownian and Active Particles in Irregular Porous Networks

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