Elastomers commonly used as sealing materials are highly networked rubbery polymers. They may contain different pollutants such as fluorinated compounds like per- and polyfluoroalkyl substances (PFAS), for example used as additives to enhance the performance of the elastomer under a variety of chemical and mechanical stresses. As of now, no reliable recycling strategy for elastomers is available and they are consequentially disposed of by incineration or in landfills. Due to the potential wash out of additives or other pollutants into landfill leachates, elastomers present a possible source of continuous environmental pollution. A processing protocol for elastomers is required as a basis to enable the reliable determination of extractable fluorine: Here, we describe a quick and robust sample preparation protocol to determine extractable fluorine in various sealing materials. The optimization was aimed for time efficiency and robustness of results; sample preparation was conducted for fluorine sum parameter analysis via high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). Samples were first roughly shredded to 2mm and then further milled and sieved to defined particle size fractions. Different size fractions were tested and the extraction of the size fraction between 125 and 250µm was found to be the best trade-off between extraction efficiency, time efficiency and sample loss. Subsequent methanolic or aqueous extraction and HR-CS-GFMAS analysis of various polymer samples revealed quantifiable extractable fluorine content for most samples. In the future, the sample processing method developed could make a valuable contribution as a standard operating procedure (SOP) for a time-efficient sample preparation for subsequent extraction and screening of sealing materials in prospect of the strict regulation on PFAS proposed by the European Chemicals Agency (ECHA).

Thin-film composite (TFC) membranes fabricated by interfacial polymerization (IPz) underpin modern separations, yet their chemistry remains dominated by polyamide systems. Here, we introduce a versatile thiol-ene interfacial photo-cross-linking strategy as an expansion of IPz to produce ultrathin films as membrane selective layers. In particular, vinyl-rich polymers or vinyl-functionalized nanoparticles were cross-linked with dithiols at a water/oil interface under UV irradiation in ambient air. We first show that this process can be effective for three vinyl-containing systems─poly(dimethylsiloxane) (PDMS) as poly(dimethyl-co-vinylmethyl siloxane), poly(1,2-butadiene) (PB), and vinyl-functionalized silica nanoparticles (SiNPs)─with the three systems readily forming nonporous (PDMS, PB) and porous (SiNPs) thin films. We further explored the two polymeric systems, including the impact of reaction time, dithiol type, and reactant ratio on film thickness and properties. PDMS-derived layers exhibited dense morphologies and near-zero water permeability, but with relatively thick films of 1-7 μm. Under similar reaction conditions, PB-derived films had much lower thicknesses of 60-200 nm and had minimal defects, as demonstrated by phenol/NaCl selectivities as high as 2000 under optimized thiol:ene ratios and reaction times. Infrared spectroscopy and electron microscopy supported efficient thiol-ene addition and continuous coverage of the porous support. We attribute the greater thicknesses in PDMS to greater expected permeabilities of reactants through the nascent film. This work extends thiol-ene IPz as a robust, oxygen-tolerant, and scalable platform for fabricating ultrathin selective layers, and can serve as a foundation for future work to form chemically modifiable nonporous and porous nanofilms.

We propose a precise and efficient physics-augmented neural network (PANN) to model strain-induced crystallization in rubbery polymers. We demonstrate that the model can be flexibly employed for both unfilled and filled natural rubber (NR). The approach is based on a two potential framework, similar to the concept of generalized standard materials (GSMs). To describe the material behavior, neural network-based free energy and dissipation potentials are employed. The evolution of crystallinity is derived from the two potentials. To ensure boundedness of the crystallinity, a novel constrained GSM-type evolution problem is proposed. To this end, two additional Lagrange multipliers together with the corresponding Karush-Kuhn-Tucker conditions are introduced. As a result, it is guaranteed that crystallinity can be interpreted as a variable of concentration type. The neural network-based potentials ensure all physically desirable properties by construction. Most importantly, objectivity, material symmetry and thermodynamic consistency are automatically fulfilled. In addition, an alternative derivation of the governing model equations in time-discrete form is presented based on an incremental variational framework, which also serves as the basis for a finite element implementation. We demonstrate the predictive capability of the PANN using three different experimental data sets from literature, considering both stress and crystallinity evolution at material point level as well as the corresponding field distributions in a notched specimen. Moreover, we show that model parameterization is also possible when experimental crystallinity data is not available, still enabling suitable stress predictions.

We test and demonstrate that the fundamental origin for long-range ∼200nm local property gradients between glassy and rubbery polymer domains is an acoustic impedance matching framework of boson peak wavelengths. Recent research has suggested that the transmission of λ ∼ 5 nm acoustic waves across glassy-rubbery interfaces is the cause of dynamical gradients leading to the broad ≈250nm glass transition Tg(z) and modulus G̃(z) profiles observed between polymer domains. These acoustic waves with wavelength λ ∼ 5 nm are of comparable energy to the boson peak and the collective vibrations associated with precursors of structural rearrangements. In this work, we directly test this proposed conceptual framework by inserting a 5nm impedance-matching random copolymer layer at the interface between glassy polystyrene (PS) and rubbery polybutadiene (PB) domains. The resulting viscoelastic changes of PS/PB bilayer films are studied using a quartz crystal microbalance, where an acoustic transfer-matrix continuum mechanics model is used to determine the change in depth-dependent modulus G̃(z) imparted by the added 5nm styrene-butadiene copolymer P(S-r-B). We find the emergence of the broad modulus gradient to be accelerated by the added 5nm copolymer layer. These results demonstrate a direct correlation between compositional interfacial widths wI ≈ 5-10nm and the broad ≈100-300nm G̃(z) modulus gradient that emerges between glassy and rubbery domains, supporting the idea that it is the transmission of λ ∼ 5 nm acoustic waves across dynamically distinct domains that is key to the mechanism behind the coupling of local properties between them. More broadly, these findings provide new insight into the fundamental nature and mechanisms behind the length scales impacting local dynamical heterogeneity of glasses.

Designing efficient mechanisms for moving mechanical assemblies requires the use of materials with well-defined mechanical responses. Appropriate methods are needed to characterize these mechanical responses. Mechanical characterization of soft materials is critical in the high strain rate regime where intuition from manipulating a material at low rates fails to translate to applications including impact protection, tire traction, and sound damping. Here, transient grating spectroscopy (TGS) is used to measure wave propagation for soft elastomers and hydrogels. TGS is a non-destructive and non-contact optoacoustic technique that enables high strain rate measurements of the bulk modulus, a measure of a material's resistance to changing volume. The bulk modulus of elastomers and hydrogels is measured using TGS and its conversion to Young's modulus is discussed. This data is used to resolve values of Poisson's ratio in nearly incompressible gels to high degrees of precision.

3D-printed digital materials whose mechanical behavior travels between those from thermoplastic to rubbery polymers have become increasingly important. However, their mechanical functionalities have not been fully exploited due to intrinsic...

Leachables from polymeric medical devices can migrate into the body, potentially impacting patient health. Physics-based mass-transport models can estimate patient exposure but require knowledge of the initial leachable amount, . Although can be determined through exhaustive extraction testing, this may be impractical for some solutes due to kinetic or thermodynamic limitations. We developed a free-volume model to estimate from non-exhaustive extractions, accounting for solvent-swelling effects on solute diffusivity, , in polymers. Based on an analysis of polymer/solvent partition coefficients, we also propose a limiting value for the partition coefficient . We couple this model to a mass-transport equation to predict . Validation against experimental data demonstrates order-of-magnitude accuracy for both and . The model is applicable only to rubbery polymers and systems involving relatively hydrophobic polymers, solvents, and solutes. Using the predicted with a transport model for invivo exposure yields results similar to those obtained when is known a priori. Our work shows that non-exhaustive extractions can be used to infer total extractable quantities and conservatively estimate patient exposure.

A network alteration theory of rubbery polymers for exploring the damage and mechanochemistry

This study proposes a novel nonaffine constitutive model to explore the functionality dependence and blob motion of rubbery polymer networks. The model posits that the deformation of polymer networks comprises two parts: the nonaffine motion of cross-linking points and the additional motion of polymer blobs. Building on the p-chain model, polymers are conceptualized as aggregates of homogeneous unit cells undergoing initial phantom deformations, followed by additional movements to align with macroscopic block deformations. The collapse of polymer blobs is analyzed through phantom network, kinetic energy, and the deformation gradient. The functionality (f) and the second invariant (I2) are identified as pivotal factors in understanding nonaffine deformations. The proposed model was validated using experimental data from vulcanized natural rubber, PAAm hydrogel, and P(BMA-co-MEA)-Li elastomers. The results demonstrate a strong alignment between theoretical predictions and experimental observations. This study provides new insights into the mechanical behavior of rubbery polymers and offers a robust framework for predicting their responses under diverse deformation conditions.

ABSTRACTRenewable feedstocks pave the way to reduce the demand for petroleum‐derived chemicals. Castor oil is one such plant‐based raw material that can be used to synthesize chemicals and materials with diverse applications. Herein, we report the synthesis of a novel monomer, 18‐methoxy‐18‐oxooctadec‐9‐en‐7‐yl methyl oxalate (3), from castor oil‐derived ricinoleic acid. The identity of the monomer 3 has been unambiguously ascertained using 1‐2D NMR spectroscopic analysis. Monomer 3 was then subjected to condensation polymerization with potentially bio‐renewable long‐chain aliphatic diols to yield degradable linear polyoxalates having molecular weights in the range of 8000–22,000 g/mol. The polymerization reactions were performed using pTSA and [Sn(Oct)2] as catalysts, and the polymerization conditions were optimized. The structure of the polymer was confirmed by 1‐2D NMR spectroscopy, IR spectroscopy, and GPC analysis. The thermal characterizations of the polyoxalates were carried out by DSC and TGA analysis. The polyoxalates were found to degrade in acidic media. These renewable polyoxalates were further reacted with thiols by “thiol‐ene” click reaction to produce a cross‐linked rubbery polymer, which retained degradability.

Abstract Efficient recovery of biobutanol, a next‐generation biofuel, from fermentation liquor remains challenging due to its low concentration and volatility. This study introduces ultrathin rubbery polymer membranes developed through an interfacial dissolution–crosslinking method, with cross‐linked polysiloxane confined within the permanent nanovoids of ceramic alumina substrates. The resulting membranes, which are less than 10 nm thick, achieve unparalleled performance: concentrating 1.0 wt% aqueous n ‐butanol 14.2‐fold with a record‐high liquid flux of 110 kg m −2 h −1 —one to two orders of magnitude greater than those of previously reported membranes. These advancements suggest significant reductions in the membrane area and operational costs for large‐scale biobutanol separation, establishing a sustainable and economical solution for biofuel production.

Efficient recovery of biobutanol, a next-generation biofuel, from fermentation liquor remains challenging due to its low concentration and volatility. This study introduces ultrathin rubbery polymer membranes developed through an interfacial dissolution-crosslinking method, with cross-linked polysiloxane confined within the permanent nanovoids of ceramic alumina substrates. The resulting membranes, which are less than 10nm thick, achieve unparalleled performance: concentrating 1.0wt% aqueous n-butanol 14.2-fold with a record-high liquid flux of 110kg m-2h-1-one to two orders of magnitude greater than those of previously reported membranes. These advancements suggest significant reductions in the membrane area and operational costs for large-scale biobutanol separation, establishing a sustainable and economical solution for biofuel production.

Rubbery soft polymer electrolyte membranes (PEMs) prepared from naturally occurring products are in high demand for the fabrication of flexible fuel cells as a multipurpose energy source to achieve a carbon-neutral society. This work describes the preparation of a rubbery soft PEM from deproteinized natural rubber (DPNR) by grafting-copolymerizing ethyl p-styrenesulfonate (SSEt) onto the surface of rubber particles in the latex stage, followed by hydrolysis with NaOH and cast film formation to construct a nanomatrix channel. The resulting rubbery soft PEM, a graft copolymer of DPNR and poly(p-styrenesulfonic acid) (DPNR-graft-PSS), is characterized by 1H NMR spectroscopy, transmission electron microscopy (TEM), impedance analysis, and tensile testing. The hydrophobic rubber particles with a diameter of about 1 μm are well dispersed in the continuous nanochannel of hydrophilic poly(p-styrenesulfonic acid) with a thickness of about 10 nm that possesses a high proton conductivity, owing to an efficient proton transportation, which is beneficial for polymer electrolyte fuel cells. σ* is the proton conductivity per unit equivalent of sulfonic acid, which is distinguished from the proton conductivity, σ. The value of σ* for the DPNR-graft-PSS prepared with 1.0 mol/kg-rubber of SSEt is 2.6 (S/cm)/meq, which is approximately 1.4 times higher than that of the perfluorosulfonic acid membrane Nafion117, whereas its σ is lower. The apparent activation energy of DPNR-graft-PSS (3.2 kJ/mol) is lower than that of Nafion117, and its stress at break (6.9 MPa) is higher than that of DPNR. The high σ*, low apparent activation energy, and outstanding tensile strength of DPNR-graft-PSS can be attributed to the formation of the nanomatrix channel.

In the present work, we use ellipsometry to extract the physical aging response of thin glassy polystyrene (PS) layers from rubbery-glassy bilayer films of poly(n-butyl methacrylate) (PnBMA) atop PS. How the soft interface between rubbery and glassy polymer domains can impact the physical aging response of glassy domains is unclear. Measurements in the literature have shown that the local glass transition temperature Tg of PS is strongly reduced near a PnBMA/PS interface with a magnitude twice as large compared to that imparted by a free surface. As the free surface is known to reduce physical aging, we anticipated large changes in the physical aging response of PS within PnBMA/PS bilayer films. However, surprisingly the aging response remained equivalent to bulk down to 75 nm PS layer thicknesses that were the thinnest we found could be accurately measured given the optical limits of dispersion. With complementary fluorescence measurements, we show that the average Tg(hPS) of such PS layers within 150 nm PnBMA/75 nm PS bilayer films are also still bulk. These findings demonstrate that films with finite domain sizes have interfacial dynamical gradients that are significantly altered from those previously measured in systems with semi-infinite domain sizes.

Post-polymerisation modification of commodity hydrocarbon-based polymers provides access to functional polymers not readily available through bottom-up synthesis methods. Here, we demonstrate the oxyfunctionalisation of different styrenic and rubbery (co-)polymers using a well-established and robust manganese-based homogeneous catalyst, MnTACN, a 1,4,7-trimethyl-1,4,7-triazacyclononane ligand-bearing di-nuclear tri-μ-oxo bridged Mn(iv) compound, and hydrogen peroxide as a green oxidant. Using various grades of polystyrene (PS) and polybutadiene (PBD), we successfully oxyfunctionalised the polymer backbones with alcohol (PS and PBD), ketone (PS) and epoxide (PBD) functional groups. Under optimised conditions, total functionalisation degrees up to 5% for PS and 18% for PBD can be achieved. Next to the homopolymers, we also show oxyfunctionalisation degrees as high as 11%, of the butadiene-derived part of a styrene–butadiene–styrene block-co-polymer (SBS). These results underscore the versatility of a single catalytic system for the oxyfunctionalisation of various C–H bonds as well as the CCreated by potrace 1.16, written by Peter Selinger 2001-2019]]>C bonds found in these commodity hydrocarbon polymers. Detailed analysis of the oxidised polymers before and after subsequent oxidative cleavage of the installed diol moieties on the PBD backbone suggest that the functional groups are randomly spaced along the polymer backbone. Moreover, this second oxidative cleavage also offers the possibility to selectively break down the polymer backbone after oxyfunctionalisation into a mixture of dialdehyde oligomers consisting of 4 up to 32 monomeric units. For PBD and low/mid Mw PS, oxyfunctionalisation coincided with minimal backbone cleavage or crosslinking, as evidenced by gel permeation chromatography (GPC). For the high molecular weight PS samples and SBS, GPC analysis suggests that backbone cleavage is in contrast more pronounced upon oxyfunctionalisation. The thermal properties of the oxyfunctionalised materials are largely unchanged, with decomposition temperatures decreasing with increasing functionalisation degrees, but overall remaining in the high thermal stability regime.

The scope of this work was to develop a thin-film composite (TFC) membrane for the separation of CO2/CO mixtures, which are relevant for many processes of gas processing and gasification of carbon-based feedstock. Special attention was given to the development of highly permeable porous polysulfone (PSF) supports (more than 26,000 GPU for CO2) since both the selective and support layers contribute significantly to the overall performance of the TFC membrane. The PSF porous support is widely used in commercial and lab-scale TFC membranes, and its porous structure and other exploitation parameters are set during the non-solvent-induced phase separation (NIPS) process. Since the casting solution properties (e.g., viscosity) and the interactions in a three-component system (polymer, solvent, and non-solvent) play noticeable roles in the NIPS process, polysulfone samples in a wide range of molecular weights (Mw = 76,000-122,000 g·mol-1) with terminal hydroxyl groups were synthesized for the first time. Commercial PSF with predominantly terminal chlorine groups (Ultrason® S 6010) was used as a reference. The PSF samples were characterized by NMR, DSC, and TGA methods, and the Hansen solubility parameters were calculated. It was found that increasing the ratio of terminal -OH over -Cl groups improved the "solubility" of PSF in N-methyl-2-pyrrolidone (NMP) and water. A direct dependence of the gas permeance of porous supports on the coagulation rate of the casting solution was identified for the first time. It was shown that the use of synthesized PSF (Mw = 76,000 g·mol-1, Mw/Mn = 3.0, (-OH):(-Cl) ratio of 4.7:1) enabled a porous support with a CO2 permeance of 26,700 GPU to be obtained, while the support formed from a commercial PSF Ultrason® S 6010 (Mw = 68,000 g·mol-1, Mw/Mn = 1.7, (-OH):(-Cl) ratio of 1:1.9) under the same conditions demonstrated 4300 GPU. The siloxane-based materials were used for the selective layer since the thin films based on rubbery polymers do not undergo the same accelerating physical aging as glassy polymers. Two types of materials were screened for the selective layer: synthesized polymethyltrifluoroethylacrylate siloxane-polydecylmethylsiloxane (50F3) copolymer, and polydimethylsiloxane (PDMS). 50F3 siloxane was studied for gas separation applications for the first time. It was shown that the permeance of composite membranes based on high-performance porous supports from the PSF samples synthesized was 3.5 times higher than that from similar composite membranes based on supports from a commercial Ultrason® S 6010 PSF with a permeance value of 4300 GPU for CO2. It was found that the enhanced gas permeance of composite membranes based on the highly permeable porous PSF supports developed was observed for both 50F3 polysiloxane and commercial PDMS. At the same time, the CO2/CO selectivity of the composite membranes with a 50F3-selective layer (9.1-9.3) is 1.5 times higher than that of composite membranes with a PDMS-selective layer. This makes the F-containing 50F3 polysiloxane a promising polymer for CO2/CO separation.

Global warming poses a significant environmental challenge, highlighting the urgent need to reduce and manage greenhouse gas emissions, especially carbon dioxide (CO2). One promising approach to mitigating this issue is membrane separation technology. Herein, the MIL-101 metal-organic framework was synthesized, characterized, and incorporated as a filler (0–40 wt.%) into Pebax®2533 polymer. Gas permeability measurements were conducted using a constant pressure module for pure gases at a fixed feed pressure (2 bar) and temperature (298 K). Various analytical techniques, such as FESEM, FTIR, TGA, and mechanical strength analyses, were employed for membrane characterization. Analytical techniques confirmed excellent particle dispersion and proper adhesion between the polymer and filler particles without void formation. The results showed substantial improvements in the selectivity for H2/N2 and CO2/N2, surpassing the values of the neat membrane by 52.33% and 52.56%, respectively, due to the narrow pore size of the filler. Despite the improvement in gas permselectivity, the permeability of all gases decreased with filler content compared to the pure membrane. Polymer chain rigidification and possible blockage of filler pores by polymer chains could be the main reasons for the decrease in gas solubility inside the Pebax rubbery polymer.

Whereas classical surface chemistry holds that capillarity controls fluid behavior, recent investigations indicate that it also dominates the mechanics of soft solids at scales below the elastocapillary length (le), which is the ratio of surface tension γ of liquid to elastic modulus E of the solid. We used atomic force microscopy to probe elastocapillary deformations induced by droplets of various radii (R) on partially wetting rubbery films of entangled polymers possessing thicknesses down to 230 nm. The transition from elasticity to capillarity dominated deformation with decreasing R values is visualized with high spatial resolution. The elasticity-to-capillarity transition shifted to lower R values, when the film thickness (h) is reduced to a threshold below approximately 10 times of the bulk le (le,bulk) values, indicative of a smaller le on the thin films. This enabled the identification of a thickness-dependent elastocapillary length (le,h) ∼ (h3γ/E)1/4 for soft polymer films on rigid substrates, and, by extension, suggests the scaling le,h ∼ h–n, where n varies with the contrast between the moduli of the films and substrates. The results resolve the foundation of the fluid wetting and interactions with thin, substrate-supported soft films.

QCM-based alcohol vapor sensors have been widely researched, and various materials have been deposited onto the sensor surface to serve as a functional layer. However, non-conductive polymers such as SBS as a functional layer for alcohol sensors are still minimally reported. In this study, the SBS was deposited on 1 side of the QCM using the spin coating technique. After deposition, the layer was annealed for 1 h. The annealing temperatures are 100, 150 and 200 °C. The concentrations of exposed alcohol vapor were 5, 10, 15, 20, 25, 50, 75 and 100 ppm. This study demonstrated that the SBS layer has the potential to be a functional layer of alcohol sensors. SBS 200 °C is an optimum functional layer for alcohol vapor sensors due to its high ∆f and sensitivity. Meanwhile, SBS 100 °C has poor ∆f and sensitivity. This is due to the morphology of 200 °C SBS, which consists of more valleys that perform as interaction sites for SBS and alcohol molecules. However, one of the limitations of SBS as a functional sensor layer for alcohol sensors is its low selectivity, which is a characteristic of rubbery polymers. HIGHLIGHTS The SBS layer annealed at higher temperatures has more valleys than the SBS layer annealed at low temperatures. The valleys in the morphology of the SBS layer act as interaction sites for alcohol molecules, where each site interacts with an alcohol molecule. It is based on the sensor response and proved by fitting the Langmuir model. The SBS layer annealed at 200 ᵒC has a high ∆f, sensitivity, and longer response time. The selectivity of SBS was relatively low, a characteristic of rubbery polymers. The interaction between SBS and methanol is physisorption. GRAPHICAL ABSTRACT

ABSTRACT A model system consisting of a 50/50 immiscible mixture of polyethylene glycol (PEG) and polytetrahydrofuran (PTHF), with covalently bound nano silica–reinforcing particles, was used to investigate how the distribution of particles affects viscoelastic properties. The rubbery polymers were generated by chain extending from their respective oligomers through hydroxyl end groups with 1,6-diisocyanato hexane. The viscosity of the resulting PEG and PTHF polymers was 32 and 1000 Pa-s, respectively. Setting the overall SiO2 concentration to 10 phr, we explored three different silica distributions: (1) all-in-PEG, 20 phr in PEG and neat PTHF; (2) uniform, 10 phr in both PEG and PTHF; and (3) all-in-PTHF, neat PEG and 20 phr in PTHF. When compared with the uniform system, the storage and loss shear moduli and the viscosity of the all-in-PTHF system showed a 20-fold increase of the stiffness at low strain, yet nearly the same viscosity at high strain. Similarly, the storage and loss moduli of all-in-PEG mixtures were roughly 1/10 that of the uniform system. The surprisingly high modulus and high viscosity of the all-in-PTHF system can be understood as the entire PTHF regions themselves becoming solid filler.