Polyzwitterions combine the attractive features of zwitterions (ZIs) with the mechanical support and processability of polymeric materials. Among these attractive features is a potential for superior permittivity, which is limited by the propensity of ZIs to pack into strongly associating assemblies. Block polymer (BP) self-assembly embodies a plethora of packing frustration opportunities for optimizing polyzwitterion permittivity. The capabilities of this novel approach are revealed here, where the static permittivity (epsilon s) of a polyzwitterionic block is enhanced to a level comparable to that of pure liquid zwitterions near room temperature (epsilon s similar to 250), but with less than a third of the ZI concentration. Structure-property mechanisms are realized deductively through a series of thermal processes and control sample experiments. Tethered ZIs within the mixed block interface are frustrated when subjected to segmental segregation under sufficient interfacial tension and packing, while noninterfacial zwitterions contribute very little to permittivity, highlighting the potential for improvement by several fold.

In this work, we report the successful synthesis of 17 unique compositions of a poly(ionic liquid) (PIL) ABC triblock terpolymer, poly(S-b-VBMIm-TFSI-b-HA), where S is styrene, VBMIm-TFSI is vinylbenzyl methylimidazolium bis(trifluoromethanesulfonyl)imide, and HA is hexyl acrylate. Nine distinct morphologies were observed, including two-phase and three-phase disordered microphase separated (D-2 and D-3), two-phase hexagonally packed cylinders (C-2), core-shell hexagonally packed cylinders (C-CS), three-phase lamellae (L-3), two-phase lamellae (L-2), core-shell double gyroid (Q(230)), spheres-in-lamellae (L-SI), and a three-phase hexagonal superlattice of cylinders (C-SL). The L-SI morphology was unambiguously confirmed using small-angle X-ray scattering and transmission electron microscopy. Morphology type significantly impacted the ion conductivity of the PIL ABC triblock terpolymers, where remarkable changes in morphology factor (normalized ion conductivity) were observed with only small changes in the conducting volume fraction, i.e., PIL block composition. An exceptionally high morphology factor of 2.0 was observed from the PIL ABC triblock terpolymer with a hexagonal superlattice morphology due to the three-dimensional narrow, continuous PIL nanodomains that accelerate ion conduction. Overall, this work demonstrates the first systematic study of highly frustrated single-ion conducting ABC triblock terpolymers with a diverse set of morphologies and exceptionally high morphology factors, enabling the exploration of transport-morphology relationships to guide the future design of highly conductive polymer electrolytes.

In this study, poly(ionic liquid) (PIL) ABC triblock and ABCBA pentablock terpolymers (PILTTP and PILPTP, respectively) were synthesized to investigate the impact of chain architecture (ABC versus ABCBA) on properties. Specifically, the morphology, ionic conductivity, mechanical properties, electrochemical stability, and lithium metal battery performance of the PILTTP and PILPTP as ternary solid polymer electrolytes (SPEs) containing corresponding lithium salt and ionic liquid (IL) (at various IL concentrations) were measured. Interestingly, the PILPTP SPEs show one order of magnitude higher Young's modulus compared to the PILTTP at the same IL concentration due to bridged conformations and interlocked entanglements of the PILPTP. The improved mechanical properties of the PILPTP SPE lead to enhanced electrochemical stability and stable battery performance over 50 cycles at room temperature, exhibiting dendrite suppressing ability. This study highlights the importance of the symmetric ABCBA structure of PIL multiblock polymers on cycling stability for solid-state lithium metal batteries.

Charge-containing polymeric materials have been widely studied for a range of applications. The fundamental relationships between the charge species, charge density, and the microscale morphology of charge-containing polymers are critical for defining the application in which they may be used. In this work, a series of thermoplastic poly(arylene ether sulfone) (PAES) copolymers with controllable sulfobetaine charge contents (0-100 mol %) and high molecular weights (Mw similar to 65 kDa) were prepared. All the zwitterionic PAESs synthesized showed thermal stability up to 250 degrees C. DSC and tensile tests showed a decreased T-g and mechanical strength with the incorporation of increasing charge density, which suggests a plasticization effect by the charged group. Electron microscopy and X-ray scattering data confirmed the absence of microphase separation in the ion-containing random copolymer system, which corroborated with the observation of a single T-g for all zwitterionic co-polymers studied. Furthermore, the relative hydrophilicity of the samples was evaluated by water uptake measurements, which revealed that the water uptake of the zwitterionic PAESs can reach up to 64% for the 72 mol% zwitterion copolymer while the free-standing film in the wet state still maintains a Young's modulus of 185 MPa. The thermoplastic charge-containing copolymers in this work demonstrated potential for applications such as coatings or water purification membranes, in which balancing hydrophilicity, processibility, and thermomechanical performance are important.

The recent surge of work expanding our understanding of complex spherical packing in block polymers (BPs) has unlocked new design space for the development of advanced soft materials. The continuous matrix phase, which percolates throughout spherical morphologies, is ideal for many applications involving transport of ions or other small molecules. Thus, determining the accessible parameter range of such morphologies is desirable. Bulk zwitterion-containing BPs hold great potential within the realm of electroactive materials while remaining relatively untapped. In this work, three architecturally and compositionally asymmetric diblock polymers were prepared with the majority of blocks having zwitterions tethered to side-chain termini at different ratios. The A15 Frank-Kasper phase was observed in two samples (similar to 15 kDa), separated by a substantially higher T-ODT after increasing the zwitterion content 1.7-fold. For the highest zwitterion content sample, phase transitioning out of the kinetically trapped, liquid-like packing (LLP) state was found to correlate with a decline in the dielectric strength of zwitterionic relaxation processes, which suggests that zwitterionic interactions are governing the phase transition kinetics. Upon slow cooling from the disordered state, Frank-Kasper phases reappeared with signs of kinetic arrest.

Nanocomposites integrate functional nanofillers into viscoelastic matrices for electronics, lightweight structural materials, and tissue engineering. Herein, the effect of methacrylate-functionalized (MA-SiO2) and vinyl-functionalized (V-SiO2) silica nanoparticles on the thermal, mechanical, physical, and morphological characteristics of poly(ethylene glycol) (PEG) nanocomposites was investigated. The gel fraction of V-SiO2 composites decreases upon addition of 3.8 wt% but increases with further addition (>7.4 wt%) until it reaches a plateau at 10.7 wt%. The MA-SiO2 induced no significant changes in gel fraction and both V-SiO2 and MA-SiO2 nanoparticles had a negligible impact on the nanocomposite glass transition temperature and water absorption. The Young's modulus and ultimate compressive stress increased with increasing nanoparticle concentration for both nanoparticles. Due to the higher crosslink density, MA-SiO2 composites reached a maximum mechanical stress at a concentration of 7.4 wt%, while V-SiO2 composites reached a maximum at a concentration of 10.7 wt%. Scanning electron microscopy, transmission electron microscopy, and small-angle X-ray scattering revealed a bimodal size distribution for V-SiO2 and a monomodal size distribution for MA-SiO2. Although aggregates were observed for both nanoparticle surface treatments, V-SiO2 dispersion was poor while MA-SiO2 were generally well-dispersed. These findings lay the framework for silica nanofillers in PEG-based nanocomposites for advanced manufacturing applications.

The small-angle scattering invariant provides a useful tool for quantifying nanoscale morphological features in two-phase materials, when scattering data of sufficient quality and angular range are available. In this work, an invariant analysis has been performed on small-angle X-ray scattering data for a series of epoxy-amines previously found to have relatively high-energy absorption (KE50) in ballistic impact tests. The improved performance was hypothesized to be a result of the formation of an ill-defined two-phase morphology, observed but not quantified using transmission electron microscopy. In this analysis, the ballistic performance and the scattering invariant were found to be strongly correlated, with a Pearson's linear correlation coefficient of 0.94. Facile analysis enabled by a custom software procedure suggests that this previously difficult analysis may be more broadly useful, even in high throughput applications.

The amount and states of water in a polymer electrolyte significantly affect the material's morphology as well as its mechanical and transport properties, and thus determine performance in many important applications such as fuel cells, electrolyzers, and other electrochemical energy conversion devices. In this study, recast H+-Nafion® films were characterized using attenuated total internal reflection FTIR (ATR-FTIR) spectroscopy before and after thermal annealing and subsequent rehydration. The states of water in the hydrated films were determined by analyzing the O–H stretching band of water using principle component analysis and multivariate curve resolution. It was found that annealing at a temperature above the glass transition temperature caused the water hydrogen-bonding networks in the water-ionic clusters to become restricted, suggesting that annealing forms a robust polymer matrix confining the water-ionic clusters. The evolution of film morphology with increasing thermal-annealing temperature was confirmed with small-angle X-ray scattering (SAXS) and CO2 diffusion measurements. Fuel cell performance tests using annealed and unannealed Nafion® in the cathode catalyst layer found improved stability when the cathode catalyst was annealed, indicating that thermal history is an important design parameter in electrochemical energy conversion device fabrication.

Considerable work has gone into the development of synthetic systems that mimic biological approaches to provide adhesion in a wide range of environments. The catechol group is a workhorse functional group for this approach, capable of promoting adhesion through a number of transient interactions and oxidation states. We previously reported the development of a family of acrylate-maleimide-catechol (PAM) copolymers that varied the side chain to govern thermal properties and polarity. Here, we have used aluminium adherends to study the performance of the PAM series in an adhesive application, employing different deposition techniques to access 'true' and plasticized T(g)s for the material. The polarity and effective T-g of the polymers had little correlation with the observed strength of adhesion, although some conclusions could be drawn about the series based on postmortem analysis and morphology characterization, where side chain assembly led to some periodic organization of the films. Adhesive strength to the adherends was sufficient to overcome the strength of the PAM, leading to a cohesive failure mode. Overall, the study revealed the importance of processing conditions and conditioning in the evaluation of novel polymer compositions. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

The role of counterion sterics on the structure and dynamics of a low glass transition temperature, amorphous poly(isoprene-ran-styrenesulfonate) copolymer was investigated using a series of symmetric, tetraalkylammonium counterions with methyl (TMA), ethyl (TEA), propyl (TPA), and butyl (TBA) pendent groups, in addition to a sodium (Na) control. A detailed analysis of the aggregate structure was achieved by fitting the copolymers' X-ray scattering profiles with a modified hard sphere model. Increasing the counterion sterics from Na to TEA resulted in slight changes to the aggregates with some ionic groups present in the isoprene matrix. For the more hindered TPA and TBA counterions, considerable disruption of the structure occurred. Using solid-state NMR, dynamic mechanical analysis, and rheology, the effect of the counterion sterics on the copolymer's dynamics was determined. The T-1p, relaxation of the copolymers revealed a rigid isoprene fraction, associated with the ion clusters, and a mobile isoprene matrix fraction. Copolymers with larger counterions exhibited an increase in the dynamic moduli at high frequency and a decrease in the dynamic moduli at lower frequencies in addition to possessing faster molecular dynamics. These two observations are attributed to an increased incorporation of ionic groups into the isoprene matrix and screening of the dipole-dipole interactions.

In this study, the physical, transport, mechanical, morphological, and electrochemical properties of a ternary blend solid polymer electrolyte (SPE) (poly(ionic liquid) (PIL) multiblock polymer, lithium salt, and ionic liquid (IL)) were systematically investigated as a function of IL concentration. With increasing IL concentration, the conductive volume increases along with the polymer chain segmental mobility. This facilitates high ionic conductivity, while the mechanical modulus exhibits a percolation threshold. Surprisingly, at higher IL concentrations, there is a reduction in the lithium cation mobility as evidenced by pulsed-field gradient nuclear magnetic resonance, which coincides with an increased overpotential evidenced by lithium metal stripping and plating. Stable lithium ion battery cycling durability (over 100 cycles at room temperature) is demonstrated with the ternary blend SPE as the electrolyte and separator. This work provides valuable insights into the design of new SPEs with both high ionic conductivity and improved battery stability.

Lithium ion batteries are currently the leading commercial technology for portable electronic devices and electric vehicles. However, new solid polymer electrolytes (SPEs) that comprehensively possess the preferred properties of high ion conductivity, high electrochemical stability, robust mechanical properties, flexibility, and good film forming properties, are required to improve the safety and lifetime of lithium ion batteries. Although diblock copolymers have been explored as SPEs and can potentially provide the orthogonal properties of high ion conduction and high mechanical strength simultaneously in a solid-state material, there are limitations to diblock copolymer-salt mixture systems, such as a limited set of morphologies, and a lack of means to achieve simultaneous combination of more than two properties ( e.g. , conductivity, strength, flexibility). Compared to diblock copolymers, multiblock polymers involve more than two polymer chemistries and therefore enable the possibility to conjoin many of the desired properties, such as high ion conductivity, mechanical strength, flexibility, good film forming properties, processability, and high electrochemical stability all into a single materials platform. In this study, a lithium ion conducting polyionic liquid pentablock terpolymer (PILPTP) was investigated as a solid polymer electrolyte (SPE) for lithium ion batteries.The morphology, chemical, thermal, mechanical, and electrochemical properties were examined as function of ionic liquid composition, cation chemistry, and film processing conditions. Coin cell Li 4 Ti 5 O 12 /SPE/LiCoO 2 batteries were fabricated with the lithium ion conducting PILPTP as the SPE and room temperature battery performance was demonstrated at high capacity and high cycle life. Overall, this work suggests, for the first time, that lithium conducting polyionic liquid multiblock polymers can be promising electrolyte candidates for developing safe and high performing room temperature solid-state lithium ion batteries.

ABSTRACTThe effects of incorporating metal‐binding ligands as chain extenders in polyurethane elastomers were investigated. Segmented polyurethanes based on 2 kDa poly(tetramethylene oxide) (PTMO) and 4,4‐methylenebis(cyclohexyl isocyanate) were polymerized using a two‐step process in which 2,6‐bis(1‐ethyl‐5‐(methoxymethyl)‐1H‐benzo[d]imidazol‐2‐yl)pyridine was added as a chain extender. The resulting polyurethanes were then metallated using stoichiometric amounts of Zn(II) metal salts with different counterions. The resulting metallopolymers have substantially improved Young's moduli, increased failure stress, and improved thermomechanical behavior. The materials were microphase‐separated into anisotropic hard domains within a PTMO matrix. Simultaneous small‐angle X‐ray scattering and tensile testing revealed the minority hard segment domains remain relatively intact during elongation, likely due to the strength of the metal–ligand complex. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1744–1757

Morphological control to precisely tailor the energy absorption bands of plasmonic particles is improving constantly, with efforts to improve the monodispersity of the designed particles leading to sharper plasmonic features in controlled spectral regions. Transitioning these highly tailored plasmonic additives into a robust polymer composite platforms while retaining their specified plasmonic features has proven challenging, with the elevated temperatures and mechanical forces involved in composite manufacturing resulting in particle agglomeration and morphology alterations. In this work, thermally stable protecting layers are developed onto tailored silver nanoplate (Ag-NPL) plasmonic additives to facilitate their survivable processing at elevated temperature. The produced coatings allow for their implementation in a facile, low-cost method to produce uniform dichroic optical polarizers based on the protected Ag-NPLs in a polymer matrix. Nanocomposites are obtained through an extrusion and injection molding process, which is shown to induce alignment of anisotropic particles based on sheer forces. As the optical position of the resonances is dependent on the morphology of the additive, and unlike other methods where the anisotropy in the NP is induced in situ, our method can be easily adapted to varying optical regimes by modifying the size and shape of the initial additive. Furthermore, the method presented in this work forgoes the need for a polymer stretching alignment mechanism which enables the ability to use various types of anisotropic particles with visible and near-infrared operating regimes.

Photocurable nanocomposites have tremendous potential in tissue engineering, advanced manufacturing, and structural, multifunctional materials. This project investigates the effect of silica (SiO2) nanoparticle loading content on the thermal, mechanical, physical, and morphological characteristics of the nanocomposite. An increased concentration of SiO2 nanoparticles causes a decrease in the gel fraction of the nanocomposite, which, at low nanoparticle loading, degrades the thermal and mechanical properties. However, further addition (>3.8 wt %) causes an increase in the glass-transition temperature, Young's modulus, and ultimate compressive strength. The addition of the nanoparticles had no significant effect on the hydrophilicity according to water uptake experiments. Small-angle X-ray scattering experiments, in conjunction with scanning electron microscopy and transmission electron microscopy, indicated a multimodal particle size distribution and the presence of large-scale aggregates.

We present a novel elastomer with an amphiphilic triblock/graft architecture, allowing it to rapidly swell in water and form a tough hydrogel. The design was motivated by uncontrolled hemorrhage, responsible for 80–90% of potentially survivable deaths of US soldiers over the past 15 years. The polymer is 5.7 times as absorbent and 3 times as tough as a state of the art gauze-based hemostatic dressing. It swells to equilibrium within seconds in phosphate buffered saline due to a microphase-separated morphology featuring a continuous mobile ionic phase supported by hydrophobic glassy domains and rubbery linkages, as observed by transmission electron microscopy and small-angle neutron scattering. Thickness-dependent swelling is as much as an order of magnitude faster than many tough hydrogels in the literature, yet toughness is comparable as a function of water content. The polymer is combined with gauze to form a rapidly swelling, fiber-reinforced hydrogel composite with promising mechanical properties.

This work investigated the morphological behavior of an acrylate-based metallo-supramolecular polymer system. RAFT (reversible addition fragmentation chain transfer) polymerization techniques were used to synthesize low molar mass, linear prepolymers of n-butyl acrylate and a 2,6-bis (1'-methylb enzimidazoly)pyridine-acrylate monomer (MeBIP-Ac) of varying concentration (2-10%). This synthesis incorporated a systematic increase of cross-link points (MeBIP ligands) pendent to the polymer backbone. A zinc(II) salt (Zn(ClO4)(2)) complexed with the pendent MeBIP ligands in a 1:2 ratio to form cross-linked polymers as free-standing films. The morphology of the neat films as well as those with added unbound MeBIP-zinc-MeBIP metal-ligand (ML) complex were characterized using transmission electron microscopy (TEM), HAADF-STEM (high angle annular dark field scanning transmission electron microscopy), energy dispersive X-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), energy-filtered TEM (EFTEM), and small-angle X-ray scattering (SAXS) techniques. A vesicle morphology in the bulk material was found for films of the neat polymer containing 2% MeBIP, while films at all other compositions exhibited a disordered microphase-separated morphology. The vesicle morphology of the 2% MeBIP films was transformed into a morphology of cylinders with the addition of unbound MeBIP-zinc-MeBIP complex.