The Shuttleworth effect ensures that at an interface, where one of the phases isan elastic solid, surface stress is not equal to the surface energy. In thispaper, we provide a free energy based approach to quantify the impact of theShuttleworth effect in the adhesion of a rigid, spherical particle on an elasticsolid. Our paper has four key findings. Firstly, we demonstrate that thedifference in the elastic-solid-particle surface stress and surface energies islinearly proportional to the adhesion energy. Secondly, we establish that thesurface stresses being larger than the surface energies provide the sufficientcondition for an energetically favorable adhesion. Thirdly, we show that for agiven adhesion energy and solid-vapor surface energy increase in particle-vaporsurface energy makes the adhesion, in presence of the Shuttleworth effect, morefavorable. Finally, and most importantly, we identify the necessary parameterspace corresponding to which the Shuttleworth effect may or may not enhance theadhesion as compared to the case that does not account for the Shuttlewortheffect. We anticipate that our findings will significantly impact ourunderstanding of a plethora of problems involving adhesion and indentation onsoft surfaces, such as nanoparticle adhesion on cells, nanoindentation basedcharacterization of soft solids, applications of adhesion-based soft lithographytechniques, etc.

Nanocrystalline cellulose (NCC) is an emerging renewable nanomaterial that ispromising for many diverse applications. As a renewable material, NCC and itsderivatives have been widely studied, focusing on their biological, chemical, aswell as mechanical properties. The electro-optical properties of NCC, however,remain relatively under explored. Birefringence is one of the importantproperties that make the NCC very attractive for photonic applications. Therode-like NCC fibers dispersed in certain solutions exhibit a specific preferredorientation which depends on their electrical charge, physical dimensions andthe type of solutions used to disperse NCC fibers. In a recent study ofKerr-effect in functionalized NCC solutions, we demonstrated that it is possibleto control the orientation of NCC fibers under an applied electric field.NCC-based spatial light modulator devices were fabricated and characterized.Results showed that the transmittance of the device can be controlled throughfrequency modulation of the applied electric field. In this paper we present thefabrication and electro-optical characterization of the device and discuss therelevant properties of NCC and future approaches to optimize and improve theircharacteristics and performance.

Cellulose is an abundant green polymer, which can be obtained in a variety ofnanoscale structures broadly grouped as nano/microfibrils (CNF/MFC), bacterialcelluloses (BC) or nano/microcrystals (CNC/CMC). There is increasing interest ofnanocelluloses by the research and industrial communities due to increasingavailable materials (facilities than can produce ton per day), impressivestrength properties, low density, renewability and biodegradability. However,one problem is the lack of knowledge on the nanomechanical properties ofcellulose nanofibrils, which creates barriers for the scientists and producersto optimize and predict behavior of the final product.

In this research, the behavior of thin filmed (t≤100 μm)cellulose nanofibrils’, located on aluminum pin stubs, under nanocompression loads were investigated using an Asylum Research MFP-3D Atomic ForceMicroscope equipped with a nanoindenter. Unloading curves were analyzed usingOliver-Pharr. As a result of 58 successful nanoindents, the average modulusvalue was estimated as 16.6 GPa with the reduced modulus value of 18.2 GPa. TheCNF Modulus values varied between 12.4 GPa – 22.8 GPa with 16.9%coefficient of variation (COV) while the reduced modulus ranged from 13.7 GPa to24.9 GPa with a 16.2 % COV.

This research provides practical knowledge for producers of nanocellulose,researchers and applications developers who focus on nanocellulose reinforcedcomposite materials.

We report fully-printed top-gate-bottom-contact organic thin-film transistorsusing substrates prepared from cellulose nanofibers and commercially availableprinting inks to fabricate the devices. Gravure printing was used to coat thesubstrate with a polymer resist to decrease the surface roughness and close thesurface. Transistor structures were fabricated using inkjet printing forconductors and gravure printing for the dielectric and semiconducting layers.The obtained transistor performance is compared to that of similar transistorson plastic substrate.

Nanocrystalline cellulose (NCC) solid films obtained from evaporated aqueous heterogeneous mixtures retain the self-assembled chiral nematic order formed in the suspension. These semi-translucent films are iridescent and reflect or transmit circularly polarized visible light (400-700nm) due to the chiral properties of the self-assembled nanostructure. This effect occurs at different wavelengths depending on the pitch of the helical structure. In this paper, NCC films have been fabricated from different recipes to produce various helix pitches. The corresponding red-shift in the optical wavelength has been obtained by means of Spectrophotometry measurements. Preliminary experiments have been performed to investigate optical polarization effects as function of angles of incidence using ellipsometry. Finally, laser micromachining results on NCC films may suggest feasibility for integration as tunable light polarizer components.

Cellulose nanocrystals (CNCs) are high-strength sustainable nanomaterials, theincorporation of which to a host polymer matrix can potentially lead tonanocomposites with superior mechanical properties. However, the mismatch insurface energy of CNCs and common structural polymers is a challenge that needsto be overcome to prevent the aggregation of CNCs and ensure the robustintegration of CNCs into a polymer matrix. Herein, we report an approachinvolving the functionalization of CNCs with maleated-anhydride polypropylene(MAPP) through diethylenetriamine (DETA) linkers to significantly enhance thecompatibility between CNCs and polypropylene. Polypropylene/modified CNCnanocomposites displayed 74% and 76% increase in elastic modulus in comparisonto neat polypropylene and polypropylene/untreated CNC nanocomposites,respectively. The tensile strength was also higher for nanocomposites withmodified CNC than neat polypropylene, as well as nanocomposites with untreatedCNCs. The tensile strength at 5.5% strain of polypropylene/modified CNCnanocomposites was 32% and 28% larger that of polypropylene andpolypropylene/untreated CNC nanocomposites, respectively. Finally, suchCNC-based nanocomposites have a lower density than many competitive systemsresulting in opportunities to propagate this environmentally-responsibletechnology to nanocomposites used in additive manufacturing, automotiveapplications, construction materials and consumer products.

In this study, the wetting behaviors of an underwater oil droplet on structuredsurfaces were investigated using molecular dynamics simulations and experiments.The wetting states and contact angles of the underwater oil droplet on differenthydrophobic surfaces were simulated. The simulation results showed that therewere three kinds of equilibrium states on the pillar surfaces: the Wenzel,cross, and Cassie states. Moreover, the equilibrium state of the underwater oildroplet transformed from a Wenzel to Cassie state when the water contact angledecreased. The contact angle of the underwater oil droplet increased as thewater contact angle decreased. Furthermore, the wetting behaviors of theunderwater oil droplet on rough polytetrafluoroethylene and silicon surfaceswere studied in experiments. The experimental results also indicated that thecontact angle of the underwater oil droplet increased as the water contact angledecreased, which corresponded well with the simulation results.

The unique and remarkable properties of graphene can be exploited as the basis toa wide range of applications. However, in spite of years of investigations thereare some important graphene properties that are not still fully understood, asfor example, its wettability. There are controversial reported results whethergraphene is really hydrophobic or hydrophilic. In order to address this problemwe have carried out classical molecular dynamics simulations of waternanodroplets shot against graphene surface. Our results show that the contactangle values between the nanodroplets and graphene surfaces depend on theinitial droplet velocity value and these angles can change from 86°(hydrophobic) to 35° (hydrophilic). Our preliminary results indicatethat the graphene wettability can be dependent on spreading liquid dynamics andwhich can explain some of the apparent inconsistencies reported in theliterature.