Si-based Li-ion battery anodes offer specific capacity an order of magnitude beyond that of conventional graphite. However, the formation of stable Si anodes is a challenge because of significant volume changes occurring during their electrochemical alloying and dealloying with Li. Binder selection and optimization may allow significant improvements in the stability of Si-based anodes. Most studies of Si anodes have involved the use of carboxymethylcellulose (CMC) and poly(vinylidene fluoride) (PVDF) binders. Herein, we show for the first time that pure poly(acrylic acid) (PAA), possessing certain mechanical properties comparable to those of CMC but containing a higher concentration of carboxylic functional groups, may offer superior performance as a binder for Si anodes. We further show the positive impact of carbon coating on the stability of the anode. The carbon-coated Si nanopowder anodes, tested between 0.01 and 1 V vs Li/Li+ and containing as little as 15 wt % of PAA, showed excellent stability during the first hundred cycles. The results obtained open new avenues to explore a novel series of binders from the polyvinyl acids (PVA) family.

Electroluminescent (EL) polymers are attractive for developing all‐organic light‐emitting devices (OLEDs) due to the potential advantages that polymeric systems may offer in the large‐scale manufacturing of electronics. Nonetheless, many of these EL π‐conjugated polymers are inherently insoluble in the solvents employed in the intended solution‐based manufacturing processes. One such polymer is poly(2,5‐dioctyl‐1,4‐phenylenevinylene) (POPPV), where the inherent lack of solubility of POPPV in organic solvents has frustrated its widespread application in devices and no OLEDs have been presented that exploit its electroluminescence characteristics. In this effort, a unique strategy is presented for the preparation of hybrid nanoparticles composed of POPPV, a green emitter (λem = 505 nm) and poly(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl) (PFO), a blue emitter (λem = 417 nm). The aqueous‐based nanoparticle dispersion composed of these hybrid particles is stable to aggregate and can be employed in the construction of OLEDs. The color characteristics of the electroluminescence for the devices can be tuned by exploiting the Förster resonance energy transfer between the polymers within a particle, while suppressing energy transfer between the particles. These aqueous‐based nanoparticle dispersions are amenable to being printed into devices through high‐throughput manufacturing techniques, for example, roll‐to‐roll printing.

One feature of colloidal arrays that make them of interest to materials scientists is the unique optical properties a periodic dielectric array with long range order can offer. Two approaches to assemble colloidal particles have been pursued, one approach involves the steric packing of hard spheres, while the other approach employs the electrostatic repulsion of the particles to procure order. A unique feature of electrostatically stabilized colloidal particles is that the interparticle distance can be varied post-assembly, [1,2] resulting in a level of optical tuning. These latter systems are generally assembled in a high-dielectric liquid medium and therefore prone to disordering with a number of stimuli. The self-assembly of the particles into a crystalline colloidal array is sensitive to the charge characteristics of the particles, as well as the environment in which assembly will occur. A number of stringent requirements must be met to insure a crystal with a reduced level of disorder; slight deviations in a range of environmental conditions can result in a poor level of organization, or the complete lack of order.[3]Asher and co-workers [4] pioneered a hydrogel encapsulation route for these electrostatically-based systems that stabilized the particles once ordered and allowed for a wider field of application. The majority of these systems are composed of simple dielectrics, such as poly(styrene), poly(methyl methacrylate), or silica, since these materials produce colloidal particles that readily self-assemble when in the appropriate environment. Nonetheless, the modification of the particles post-hydrogel encapsulation to alter or enhance the optical properties of the array poses a challenge. Although there have been demonstrated techniques to introduce various components into the interstitial regions of the ordered particles after the hydrogel film formation, [5] procedures that chemically modify the core colloids within the hydrogel film are scarce.In the current effort, we propose a general strategy for the preparation of well-defined and regioselectively functionalized ordered colloidal particles. This is achieved with the functionalization of hydrogel-stabilized colloidal arrays through a "click" chemistry approach. Click transformations, [6][7][8] specifically the copper(I)-catalyzed variant of the Huisgen 1,3-dipolar cycloaddition between azides and terminal alkynes to form 1,2,3-triazoles, [9][10][11][12] have found utility in the synthesis and/or functionalization of a range of systems, for example: polymers; [13][14][15][16][17][18] small molecules; [19][20][21][22] biomolecules; [23][24][25][26][27][28][29][30][31][32] hydrogels; [33] core-shell nanoparticles; [34,35] and surfaces. [36][37][38][39] The stability of azides and alkynes in aqueous solutions enables these functionalities to act as inert chemical handles for a range of selective chemical reactions and offers a facile route to modify ordered colloidal particles post-hydrogel stabilization. This general strategy is demonstrated through ...

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