The diffusion properties of nanoparticles in polymer nanocomposites are largely unknown and are often difficult to determine experimentally.

3D printing has been extensively applied in human‐related activities, and therefore the 3D printed nanocomposites became more popular and important in end‐use products. In the present study, we use lignin‐coated cellulose nanocrystal (L‐CNC) to reinforce 3D printed acrylonitrile butadiene styrene (ABS) and explore the effect of L‐CNC on the structural, mechanical, and thermal properties of 3D printed L‐CNC/ABS nanocomposites. The results indicate that the addition of L‐CNC foams the ABS and decreases the density of 3D printed L‐CNC/ABS nanocomposites. However, the tensile modulus and storage modulus increase by adding 4% L‐CNC. The thermal stability of 3D printed L‐CNC/ABS nanocomposites is also significantly improved as indicated by an increase in the maximum degradation temperature. The morphology of the nanocomposites reveals good dispersion and interfacial adhesion between L‐CNC and ABS. The finding indicates that the 3D printed nanocomposites become lighter and stiffer with addition of L‐CNC, which will have great potential to be applied in end‐use products. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45082.

The diffusion of nanoparticles in a polymer matrix is an area of current interest. However, a complete understanding is still limited as it is often difficult to quantify the much slower motion of nanoparticles in a polymer matrix. To combat this problem, we have developed a protocol to measure the diffusion coefficient of soft nanoparticles in a linear polymer matrix. Recently developed synthetic control over soft nanoparticle structures combined with this protocol provides a pathway to separately elucidate the effects of the molecular weight and nanoparticle softness on its diffusive behavior. These results indicate that the nanoparticle softness and deformability dictate its motion. Increasing the cross-linking density of the nanoparticle for all molecular weights increases its hardness and suppresses its motion in the linear matrix. Additionally, the nanoparticle molecular weight dependence deviates from the exponential dependence for star polymers suggesting that these nanoparticles benefit from the cooperative motion of the matrix to open pathways for the nanoparticle. Finally, comparison of these experimentally determined values to the Stokes–Einstein theory demonstrates that the nanoparticles diffuse much slower than a hard sphere. This is interpreted to indicate that there exist additional interactions between the nanoparticle and polymer matrix that are not captured by Stokes–Einstein, including threading or entanglement of the linear chain with the nanoparticle.