Coassembly of nanoparticles with different size-, shape-, and composition-dependent properties is a promising approach to the design and fabrication of functional materials and devices. This paper reports the results of a detailed investigation of the formation and properties of free-stranding composite films formed by the coassembly of cellulose nanocrystals and shape-isotropic plasmonic gold nanoparticles. The effect of gold nanoparticle size, surface charge, and concentration on the structural and optical properties of the composite films has been studied. The composite films retained photonic crystal and chiroptical activity properties. The size and surface charge of gold nanoparticles had a minor effect on the structure and properties of the composite films, while the concentration of gold nanoparticles in the composite material played a more significant role and can be used to fine-tune the optical properties of materials derived from cellulose nanocrystals. These findings significantly broaden the range of nanoparticles that can be used for producing nanocomposite materials based on cellulose nanocrystals. The simplicity of film preparation, the abundance of cellulose nanocrystals, and the robust, free-standing nature of the composite films offer highly advantageous features and pave the way for the generation of functional materials with coupled optical properties.

The entropically driven coassembly of nanorods (cellulose nanocrystals, CNCs) and nanospheres (dye-labeled spherical latex nanoparticles, NPs) was studied in aqueous suspensions and in solid films. In mixed CNC-latex suspensions, phase separation into an isotropic latex-NP-rich and a chiral nematic CNC-rich phase took place; the latter contained a significant amount of latex NPs. Drying the mixed suspension resulted in CNC-latex films with planar disordered layers of latex NPs, which alternated with chiral nematic CNC-rich regions. In addition, fluorescent latex NPs were embedded in the chiral nematic domains. The stratified morphology of the films, together with a random distribution of latex NPs in the anisotropic phase, led to the films having close-to-uniform fluorescence, birefringence, and circular dichroism properties.

We report the structural and optical properties of composite films formed from mixed suspensions of cellulose nanocrystals (CNCs) and fluorescent latex nanoparticles (NPs). We explored the effect of NP concentration, size, surface charge, glass transition temperature and film processing conditions on film structure and properties. The chiral nematic order, typical of CNC films, was preserved in films with up to 50 wt% of negatively-charged latex NPs. Composite films were characterized by macroscopically close-to-uniform fluorescence, birefringence, and circular dichroism properties. In contrast, addition of positively charged latex NPs led to gelation of CNC-latex suspensions and disruption of the chiral nematic order in the composite films. Large latex NPs disrupted the chiral nematic order to a larger extend than small NPs. Furthermore, the glass transition of latex NPs had a dramatic effect on the structure of CNC-latex films. Latex particles in the rubbery state were easily incorporated in the ordered CNC matrix and improved the structural integrity of its chiral nematic phase.

Abstract:The entropically driven coassembly of nanorods (cellulose nanocrystals,C NCs) and nanospheres (dye-labeled spherical latex nanoparticles,N Ps) was studied in aqueous suspensions and in solid films.I nm ixed CNC-latex suspensions,p hase separation into an isotropic latex-NP-richa nd ac hiral nematic CNC-richp hase took place;t he latter contained as ignificant amount of latex NPs.D rying the mixed suspension resulted in CNC-latex films with planar disordered layers of latex NPs,w hich alternated with chiral nematic CNC-richr egions.I na ddition, fluorescent latex NPs were embedded in the chiral nematic domains.T he stratified morphology of the films,t ogether with ar andom distribution of latex NPs in the anisotropic phase,l ed to the films having close-to-uniform fluorescence,b irefringence,a nd circular dichroism properties.Coassembly of nanoparticles (NPs) with distinct shape-, size-, and composition-dependent properties is ap romising approach for the preparation of multicomponent nanostructured materials with new or enhanced properties. [1][2][3][4] To form am aterial with ad esired nanostructure,f undamental understanding has to be developed about the governing principles of the coassembly process.For example,the structure of linear chains assembled from different types of plasmonic NPs depends on the relationship between the rate of self-assembly of each individual component and the rate of coassembly. [5,6]

Summary Amidst the pandemic, Canada has taken critical steps to curb the transmission of the 2019 novel coronavirus disease (COVID-19). A key intervention has been physical distancing. Although physical distancing may protect older adults and other at-risk groups from COVID-19, research suggests quarantine and isolation may worsen mental health. Among older adults, social exclusion and social safety nets are social determinants of health (SDOH) that may be uniquely affected by the COVID-19 physical distancing measures. Health promotion programmes designed to reduce social exclusion and enhance social safety nets are one way to mitigate the potential mental health implications of this pandemic. The Student–Senior Isolation Prevention Partnership (SSIPP) is a student-led, community health promotion initiative that has scaled into a nation-wide effort to improve social connection among older adults. This initiative began with in-person visits and transformed into a tele-intervention guided by health promotion principles due to COVID-19. SSIPP continued to target the SDOH of social exclusion and social safety nets by pairing student volunteers with older adults to engage in weekly phone- and video-based interactions. Informed by the community partnership model by Best et al., SSIPP is built on the three orientations of empowerment, behaviour and organization, which are achieved through cross-disciplinary collaboration. This article reviews the importance of the adaptability of health promotion programmes, such as SSIPP during a pandemic, placing an emphasis on the lessons learned and future steps.