Determination and prediction of physical properties of cellulose nanocrystals from dynamic light scattering measurements

Cellulose nanocrystal (CNC) has attracted increasing interest due to their biocompatibility, rigidity, and potential applications in biomedicine and cosmetics. A parameter estimation technique was used to calculate the average dimension of CNC with different aspect ratios, and their dynamic physical parameters denoted by the translational (D t) and rotational diffusion (Θ) coefficients. For CNC with L/d ratio of 17, the experimental D t and Θ values produced calculated length (L) and diameter (d) values that deviated from the experimental results by 0.22 and 0.27 % after 1,000 iterations, respectively. The calculated translational and rotational coefficients converged to an asymptotic value of 5.048 × 10−12 m2 s−1 and 551.9 s−1, with the latter requiring a larger number of iterations to achieve convergence. Close agreement between experimentally obtained and calculated dimensions and dynamics (L, d, D t, and Θ) for various types of CNCs was observed using this technique. By combining the theoretical model formulated by Broersma and the computational method utilizing a Nelder–Mead simplex direct search algorithm, reliable predictions of the average sizes determined from dynamic light scattering of a CNC sample was achieved; yielding an average L = 253.5 nm and d = 15.7 nm. The proposed approach provides a convenient, simple, and robust technique to determine the length and diameter of rod-like nanoparticles, such as CNC from light scattering measurements.