The dearth of knowledge on the diverse structures and functions in bacterial collagen-like proteins is in stark contrast to the deep grasp of structures and functions in mammalian collagen, the ubiquitous triple-helical scleroprotein that plays a central role in tissue architecture, extracellular matrix organization, and signal transduction. To fill and highlight existing gaps due to the general paucity of data on bacterial CLPs, we comprehensively reviewed the latest insight into their functional and structural diversity from multiple perspectives of biology, computational simulations, and materials engineering. The origins and discovery of bacterial CLPs were explored. Their genetic distribution and molecular architecture were analyzed, and their structural and functional diversity in various bacterial genera was examined. The principal roles of computational techniques in understanding bacterial CLPs' structural stability, mechanical properties, and biological functions were also considered. This review serves to drive further interest and development of bacterial CLPs, not only for addressing fundamental biological problems in collagen but also for engineering novel biomaterials. Hence, both biology and materials communities will greatly benefit from intensified research into the diverse structures and functions in bacterial collagen-like proteins.

Block copolyelectrolytes are solid-state singleion conductors which phase separate into ubiquitous microdomains to enable both high ion transference number and structural integrity. Ion transport in these charged block copolymers highly depends on the nanoscale microdomain morphology; however, the influence of electrostatic interactions on morphology and ion diffusion pathways in block copolyelectrolytes remains an obscure feature. In this paper, we systematically predict the phase diagram and morphology of diblock copolyelectrolytes using a modified dissipative particle dynamics simulation framework, considering both explicit electrostatic interactions and ion diffusion dynamics. Various experimentally controllable conditions are considered here, including block volume fraction, Flory−Huggins parameter, block charge fraction or ion concentration, and dielectric constant. Boundaries for microphase transitions are identified based on the computed structure factors, mimicking small-angle X-ray scattering patterns. Furthermore, we develop a novel "diffusivity tensor" approach to predict the degree of anisotropy in ion diffusivity along the principal microdomain orientations, which leads to highthroughput mapping of phase-dependent ion transport properties. Inclusion of ions leads to a significant leftward and upward shift of the phase diagram due to ion-induced excluded volume, increased entropy of mixing, and reduced interfacial tension between dissimilar blocks. Interestingly, we discover that the inverse topology gyroid and cylindrical phases are ideal candidates for solid-state electrolytes in metal-ion batteries. These inverse phases exhibit an optimal combination of high ion conductivity, well-percolated diffusion pathways, and mechanical robustness. Finally, we find that higher dielectric constants can lead to higher ion diffusivity by reducing electrostatic cohesions between the charged block and counterions to facilitate ion diffusion across block microdomain interfaces. This work significantly expands the design space for emerging block copolyelectrolytes and motivates future efforts to explore inverse phases to avoid engineering hurdles of aligning microdomains or removing grain boundaries.

Establishing the “Materials 4.0” paradigm requires intimate knowledge of the virtual space in materials design.

Although tremendous efforts have been devoted to enhance thermal conductivity in polymer fibers, correlation between the thermal-drawing conditions and the resulting chain alignment, crystallinity, and phonon transport properties have remained obscure. Using a carefully trained coarse-grained force field, we systematically interrogate the thermal-drawing conditions of bulk polyethylene samples using large-scale molecular dynamics simulations. An optimal combination of moderate drawing temperature and strain rate is found to achieve highest degrees of chain alignment, crystallinity, and the resulting thermal conductivity. Such combination is rationalized by competing effects in viscoelastic relaxation and condensed to the Deborah number, a predictive metric for the thermal-drawing protocols, showing a delicate balance between stress localizations and chain diffusions. Upon tensile deformation, the thermal conductivity of amorphous polyethylene is enhanced to 80% of the theoretical limit, that is, its pure crystalline counterpart. An effective-medium-theory model, based on the serial-parallel heat conducting nature of semicrystalline polymers, is developed here to predict the impacts from both chain alignment and crystallinity on thermal conductivity. The enhancement in thermal conductivity is mainly attributed to the increases in the intrinsic phonon mean free path and the longitudinal group velocity. This work provides fundamental insights into the polymer thermal-drawing process and establishes a complete process-structure-property relationship for enhanced phonon transport in all-organic electronic devices and efficiency of polymeric heat dissipaters.

We present a combination of first-principles calculations and the Boltzmann transport theory to understand the carrier transport and thermoelectric performance of mixed halide perovskite alloys CsPb­(I1–x Br x )3 with different Br compositions. Our computational results correlate the conduction band splitting in CsPb­(I1–x Br x )3 to the significant anisotropy in their carrier transport properties, such as effective masses and deformation potential constants. Such band splitting originates from the symmetry-broken crystal structures of CsPb­(I1–x Br x )3 polymorphs: with residue stresses/strains in asymmetric CsPb­(I1–x Br x )3, nondegenerate orbitals reconstruct the conduction band and reduce the Pb-halide antibonding character along certain directions. While the Seebeck coefficient (S) and the relaxation time-normalized electrical conductivity (σ/τ) show weak directional anisotropy, the carrier relaxation time (τ) is highly direction-dependent. The reconstruction of the conduction band finally leads to significantly anisotropic and enhanced thermoelectric power factors (PF = S 2σ) in CsPb­(I1–x Br x )3 compared to those in pure CsPbI3 and CsPbBr3, showing anomalous nonlinear alloy behavior. A delicate balance between S 2σ and combined measurement of the carrier effective mass and deformation potential constant, m*E DP, is confirmed. The lattice thermal conductivities of CsPb­(I1–x Br x )3 are significantly suppressed compared to those of their pure counterparts due to strong mass disordering and strain fields upon halogen substitution. As a result, symmetry breaking in CsPb­(I1–x Br x )3 leads to anisotropy in carrier transport, high PF, and scattered phonon transport (ultralow thermal conductivity), concurrently contributing to their promising thermoelectric figures of merit (ZT) up to 1.7 at room temperature. The principles behind the asymmetry-induced factors would serve as new design concepts to tailor the thermoelectric properties of alloys, mixtures, superlattices, and low-dimensional materials.

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The ability to fabricate anisotropic collagenous materials rapidly and reproducibly has remained elusive despite decades of research. Balancing the natural propensity of monomeric collagen (COL) to spontaneously polymerize in vitro with the mild processing conditions needed to maintain its native substructure upon polymerization introduces challenges that are not easily amenable with off-the-shelf instrumentation. To overcome these challenges, we have designed a platform that simultaneously aligns type I COL fibrils under mild shear flow and builds up the material through layer-by-layer assembly. We explored the mechanisms propagating fibril alignment, targeting experimental variables such as shear rate, viscosity, and time. Coarse-grained molecular dynamics simulations were also employed to help understand how initial reaction conditions including chain length, indicative of initial polymerization, and chain density, indicative of concentration, in the reaction environment impact fibril growth and alignment. When taken together, the mechanistic insights gleaned from these studies inspired the design, iteration, fabrication, and then customization of the fibrous collagenous materials, illustrating a platform material that can be readily adapted to future tissue engineering applications.

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