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Cellulose nanocrystals (CNCs) are naturally-sourced nanoparticles that can be used to modify polymers and provide exceptional mechanical properties to nanocomposite materials. In this study, CNCs were incorporated into water-based pressure sensitive adhesives (PSAs) via in situ semi-batch emulsion polymerization to improve PSA properties. A sequential design approach was used to improve CNC/poly(n-butyl acrylate/vinyl acetate) nanocomposite PSAs. In the first part of the design, the effects of acrylic acid (AA) and anionic surfactant sodium dodecyl sulfate (SDS) were examined in the presence of 0.5 wt% CNCs (based on polymer mass). While the SDS was crucial to maintaining latex stability, its excessive addition led to a decrease in PSA performance, namely tack and peel strength. The AA comonomer was pivotal in improving the shear strength of the PSAs, especially in the presence of CNCs. In all cases, the addition of CNCs led to improved PSA shear strength. In the second part of the design, the addition of 1-dodecanethiol (NDM) as a chain transfer agent (CTA) with CNC levels up to 1 wt% led to an improvement in tack and peel strength but at the cost of diminishing the shear strength. Generally, the addition of CNCs improved PSA performance. Thus, to maximize the impact of CNCs on PSA properties, a careful balance of SDS (for latex stability), AA (to improve shear strength) and NDM (to improve tack and peel strength) are needed.

Nanocelluloses (i.e., bacterial nanocellulose, cellulose nanocrystals, and cellulose nanofibrils) are cellulose-based materials with at least one dimension in the nanoscale. These materials have unique and useful properties and have been shown to assemble at oil-water interfaces and impart new functionality to emulsion and latex systems. Herein, the use of nanocellulose in both emulsions and heterogeneous water-based polymers is reviewed, including dispersion, suspension, and emulsion polymerization. Comprehensive tables describe past work employing nanocellulose as stabilizers or additives and the properties that can be tailored through the use of nanocellulose are highlighted. Even at low loadings, nanocellulose offers an unprecedented level of control as a property modifier for a range of emulsion and polymer applications, influencing, for example, emulsion type, stability, and stimuli-responsive behavior. Nanocellulose can tune polymer particle properties such as size, surface charge, and morphology, or be used to produce capsules and polymer nanocomposites with enhanced mechanical, thermal, and adhesive properties. The role of nanocellulose is discussed, and a perspective for future direction is presented.

Multi-component polymers can provide many advantages over their homopolymer counterparts. Terpolymers are formed from the combination of three unique monomers, thus creating a new material that will exhibit desirable properties based on all three of the original comonomers. To ensure that all three comonomers are incorporated (and to understand and/or predict the degree of incorporation of each comonomer), accurate reactivity ratios are vital. In this study, five terpolymerization studies from the literature are revisited and the &lsquo, ternary&rsquo, reactivity ratios are re-estimated. Some recent studies have shown that binary reactivity ratios (that is, from the related copolymer systems) do not always apply to ternary systems. In other reports, binary reactivity ratios are in good agreement with terpolymer data. This investigation allows for the comparison between previously determined binary reactivity ratios and newly estimated &lsquo, reactivity ratios for several systems. In some of the case studies presented herein, reactivity ratio estimation directly from terpolymerization data is limited by composition restrictions or ill-conditioned systems. In other cases, we observe similar or improved prediction performance (for ternary systems) when &lsquo, reactivity ratios are estimated directly from terpolymerization data (compared to the traditionally used binary reactivity ratios). In order to demonstrate the advantages and challenges associated with &lsquo, reactivity ratio estimation, five case studies are presented (with examples and counter-examples) and troubleshooting suggestions are provided to inform future work.

Aerogels are porous super materials that have many desirable properties including high surface areas which cause them to have significant gas adsorption. In this study, carbon aerogel and resorcinol-formaldehyde (RF) aerogel are compared with six commercial activated carbons (Derived from wood, coconut shells, polymers, and bituminous coal). This study investigates many intrinsic properties of these carbons including surface area, pore size, presence and type of surface groups, as well as ash content and determines their influence on the adsorption of CO2, N2, O2, and Ar using pure gas adsorption isotherms. This study noted that there was no trend for ash content but a strong correlation existed between the adsorption capacity and the pore size in the higher pressure region according to Dubinin's micropore volume filling theory. In the lower pressure range, the heterogeneous nature of the surface dominates the adsorption particularly for CO2 which has the strongest polarizability and quadrupole moment of the probe molecules investigated. The two aerogel samples were then further investigated by determining their adsorption in the presence of air using the temperature dependant Toth model with N2 and O2 being adsorbed significantly more than CO2 and Ar at ambient conditions, due to their much higher compositions in the air.

Aerogels are porous media that have large internal surface areas causing them to have significant gas adsorption. The adsorption isotherms of carbon dioxide, nitrogen, oxygen, and argon with a tetramethoxysilane (TMOS) silica aerogel, a [trimethylsilyl]oxy (TMS)-modified silica aerogel, and a silica gel were measured in the pressure range of 0–6.5 atm at 10 °C, 30 °C, 50 °C, 70 °C, and 90 °C. These isotherms were fitted to Langmuir, Freundlich, Sips, and Toth isotherms, as well as the temperature dependent Toth model and their cumulative adsorption of the components of air were discussed. Isosteric heats of adsorption were quantified. With this data, we can see the impact of the surface groups on adsorption as well as the pore size, with a significant increase in the quantity and strength of adsorption of CO2 reported between silanol and TMS groups. The relationship between adsorption capacity and the thermal properties of silica aerogels were also discussed in this study.