Nacre-mimetics hold great promise as mechanical high-performance and functional materials. Here we demonstrate large progress of mechanical and functional properties of self-assembled polymer/nanoclay nacre-mimetics by using synthetic nanoclays with aspect ratios covering three orders in magnitude (25-3,500). We establish comprehensive relationships among structure formation, nanostructuration, deformation mechanisms and mechanical properties as a function of nanoclay aspect ratio, and by tuning the viscoelastic properties of the soft phase via hydration. Highly ordered, large-scale nacre-mimetics are obtained even for low aspect ratio nanoplatelets and show pronounced inelastic deformation with very high toughness, while those formed by ultralarge nanoplatelets exhibit superb stiffness and strength, previously only reachable for highly crosslinked materials. Regarding functionalities, we report formerly impossible glass-like transparency, and excellent gas barrier considerably exceeding earlier nacre-mimetics based on natural nanoclay. Our study enables rational design of future high-performance nacre-mimetic materials and opens avenues for ecofriendly, transparent, self-standing and strong advanced barrier materials.

Injectable biomaterials provide the advantage of a minimally invasive application but mostly lack the required structural complexity to regenerate aligned tissues. Here, we report a new class of tissue regenerative materials that can be injected and form an anisotropic matrix with controlled dimensions using rod-shaped, magnetoceptive microgel objects. Microgels are doped with small quantities of superparamagnetic iron oxide nanoparticles (0.0046 vol %), allowing alignment by external magnetic fields in the millitesla order. The microgels are dispersed in a biocompatible gel precursor and after injection and orientation are fixed inside the matrix hydrogel. Regardless of the low volume concentration of the microgels below 3%, at which the geometrical constrain for orientation is still minimum, the generated macroscopic unidirectional orientation is strongly sensed by the cells resulting in parallel nerve extension. This finding opens a new, minimal invasive route for therapy after spinal cord injury.

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Sowing the seeds: A simple strategy based on self-seeding allows large single crystals of long regioregular poly(3-hexylthiophene) chains to be grown from solution. When appropriately crystallized, materials differing in their degrees of regioregularity and molecular weights formed monoclinic form II crystals with interdigitated hexyl side groups (see picture).

solution processing with interesting optoelectronic properties such as high charge transport mobility. Many of the best performing conjugated polymers, including the poly(alkylthiophene)s, derive their high charge mobility from an ability to crystallize. [ 1 , 2 ] While charge transport along an individual conjugated chain is predicted to be extremely rapid, [ 3 ] over longer distances charge must also pass between chains. [ 4 ] Crystallization aids interchain charge transfer by bringing planarized chains together in regular, more intimate contact. The importance of crystalline morphology has been established by previous studies reporting the sensitivity of measured charge transport to fi lm formation parameters that impose the kinetics of crystallization. [5][6][7] However, systematic study of transport-limiting morphological features and how one might optimize crystalline structure remain extremely challenging because of the diffi culty of incremental control over crystallization. In particular, typical solution casting conditions (even from high boiling point carrier solvents [ 5 ] ) lead to extremely high nucleation density, such that macroscopic charge transport probes average over an enormous number of randomly oriented grain boundaries whose density is neither well-known or easily adjusted. [ 8 , 9 ] Methodologies, such as self seeding, adapted from studies of classical semicrystalline polymers, exist that permit systematic control of important morphological characteristics such as nucleation density and lamellar width. We show how controlled solvent swelling and deswelling of a precast poly(3-hexylthiophene) (P3HT) fi lm is an extremely effective method for controlling crystalline morphology (independent of fi lm formation) by fully incremental control of nucleation density over many orders of magnitude.In P3HT and many other main chain conjugated polymers, crystallization is dominated by strong π − π interactions perpendicular to the thiophene ring, which drive a highly anisotropic growth of stacked aggregates. When confi ned to a thin fi lm, the π -stacking [010] direction lies in-plane, with the molecules adopting an edge-on orientation ([100] alkyl side chains aligned perpendicular to the substrate). Long crystalline lamellae separated by amorphous regions containing chain folds and ends provide effi cient in-plane transport channels along the π -stacking direction. Device transport characteristics, While molecular ordering via crystallization is responsible for many of the impressive optoelectronic properties of thin-fi lm semiconducting polymer devices, crystalline morphology and its crucial infl uence on performance remains poorly controlled and is usually studied as a passive result of the conditions imposed by fi lm deposition parameters. A method for systematic control over crystalline morphology in conjugated polymer thin fi lms by very precise control of nucleation density and crystal growth conditions is presented. A precast poly(3-hexylthiophene) fi lm is fi rst swollen into a solution-lik...