One-dimensional nanomaterials including cellulose nanocrystals (CNCs) and gold nanorods (GNRs) are widely used in optical materials due to their respective inherent features: birefringence with accompanying light retardation and surface plasmon resonance (SPR). Herein, we successfully combine these properties of both nanorods to generate synergistic and readily tunable structural colors in hybrid composite polymer films. CNCs and GNRs are embedded either in the same or in separate films after unidirectional alignment in dynamic hydrogels. By synergistically leveraging CNCs and GNRs with diverse amounts in hybrid films or stacked separate films, wide-ranging structural colors are obtained, far beyond those from films solely with aligned CNCs or GNRs. Higher GNR contents enhance light absorption at 520 nm with promoted magenta colors, while more CNCs affect the overall phase retardation with light absorption between 400 and 700 nm between crossed polarizers. Moreover, adjusting the angles between films solely with CNCs or GNRs via a stacking/rotating technique successively manipulates colors with flexible film combinations. By rotating the films with aligned GNRs (0–180°), light absorption can traverse from ∼500 to 650 nm. Thus, tuning the adjustable synergism of birefringence of CNCs and SPR of GNRs provides great potential for structural colors, which enlightens inspirations for designing functional optical materials.

Bilayer hydrogels crosslinked by vinylated Pluronic F127 micelles show independent thermo-, pH-, and salt-responsiveness, and outstanding toughness, which have great potentials for soft robotics, actuators, and artificial muscles.

nontoxicity, [4] large availability due to the inexhaustible origin of raw materials, excellent mechanical properties with very high elastic modulus, [5] high aspect ratio showing specific anisotropic properties, abundant surface groups, the feasibility of forming specific chiral structures in aqueous suspensions, [6] tunable surface chemistry, [1,7] and amphiphilicity. [8] Therefore, they are emerging as sustainable and important candidates in many application scenarios. [9] Previous works on the method for preparation of nanocelluloses have made extraordinary progresses, [9] including mechanical refining, [10] chemical acid hydrolysis, [11] oxidation method, [12] and so on. [13] In these methods, mechanical refining generally consumes more energy to separate the cellulose-contained resource into nanocelluloses. On the other hand, the isolation via chemical acid hydrolysis, [11] or oxidation which include the 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation and ammonium persulfate (APS) oxidation can reduce the energy consumption by 20 to 30 times for the preparation of the same amount of nanocelluloses. [14] Generally, CNFs with dimensions of 3-7 nm in diameter and 500-2000 nm in length can be prepared via TEMPO-mediated oxidation (TEMPO/NaClO/NaClO 2 with pH 4-7 and TEMPO/NaBr/NaClO with pH 10). [15] CNCs with the dimensions of 3-5 nm in diameter and 50-300 nm in length can be obtained via the methods of acid hydrolysis, [16] APS oxidation, [17] and TEMPO-mediated oxidation (TEMPO/ NaClO/NaClO 2 with pH 4.8). [18] Among these, CNFs and CNCs can be prepared by TEMPO-mediated oxidation method, however, it has to be assisted a homogenizer with high energy consumption (such as 300 W for 5 min). [15,18] It is also worth noting that the intense mechanical treatment is generally required after aforementioned acid hydrolysis and oxidation. As well, the starting materials for the isolation of nanocelluloses must be pretreated to separate the cellulose from the native matrix, e.g., softwood spruce and hardwood beech. Currently, it is highly desired to develop a facile method to prepare CNCs and CNFs via a one single method with low energy consumption and without big change of the method, when dealing with the possible complex market needs of CNFs and CNCs in the future.Here, we report a facile method to produce nanocelluloses by oxidizing native softwood spruce (SW) and hardwood beech (HW) via alkaline periodate oxidation (PO-nanocelluloses refers to both PO-CNFs and PO-CNCs from the alkaline periodate oxidation). The modification on the chemical structure of the Herein, cellulose nanofibers (PO-CNFs) and cellulose nanocrystals (PO-CNCs) are prepared directly from native softwood spruce and hardwood beech via the same alkaline periodate oxidation under equal conditions. PO-CNFs and PO-CNCs are obtained by simply regulating the reaction time between 2 and 7 d. Of particular note, the preparation of CNFs is achieved using the alkaline periodate oxidation. PO-CNFs obtained from spruce and beech ha...

Heterogeneous structures are ubiquitous in natural organisms. Native heterogeneous structures inspire many artificial structures that are playing important roles in modern society, while it is challenging to identify the relevant factors in forming these structures due to the complexity of living systems. Here, hybrid hydrogels consisting of flexible polymer networks with embedded stiff cellulose nanocrystals (CNCs) are considered as an open system to simulate the generalized formation of heterogeneous core-sheath structures, which are formed as the dynamic response to external environment. As the result of environmental adaption during modified air drying processes of hybrid hydrogels, the formation of heterogeneous core-sheath structure was found to be correlated to the relative evaporation speed. The formation of such heterogeneity in xerogel fibers was found to be correlated with Deborah number (De). During the transition of De from large to small values with accompanying morphologies, the turning point was around De = 1. The mechanism can be considered a relative humidity-dependent glass transition behavior. These unique heterogeneous structures play a key role in tuning water permeation and water sorption capacity. Insights into these aspects can prospectively contribute to a better understanding of the native heterogeneous structures for bionics design.