Folder named “Figure-1” has nine folders: folders named “Figure-1a, Figure-2a, Figure-3a, Figure-4a” contain STEM images of CMPs-S, CMPs-M, CMPs-L, and CMPs-XL, respectively. The four samples were measured on a Mira3 system (TESCAN) operated at 30 kV and a working distance of 5 mm. Folders named “Figure-1e, Figure-1f” contain width and length data of CMPs-S, CMPs-M, CMPs-L, and CMP-XL, respectively. Folder named “Figure-1g” contains a picture (taken by a regular camera) of light passing through suspensions of CMPs-L, CMPs-M, CMPs-S, CMPs-XL (concentration is 0.1% in weight percentage) and water. Folder named “Figure-1h” contains the data for reflectance of the four CMP suspensions CMPs-S, CMPs-M, CMPs-L, and CMP-XL (0.1% in weight percentage), measured with an integrating sphere. Folder named “Figure 1-i” contains four text data files about the optical simulations of the scattering cross section of the four different CMP: CMPs-L, CMPs-M, CMPs-S, CMPs-XL. These four files were generated from the optical numerical simulations in Lumerical (a software using the finite difference time domain (FDTD) method), to process these data for the four types of CMPs by Origin software, we can get the cross-section curves of each CMPs.

Folder named “Figure-2” has four folders: folder named “Figure-2a” has a picture taken by a regular camera showing a typical white film (9 μm in thickness) made from CMPs-L particles. Folder named “Figure-2b” has a SEM image the cross section of the white film made with CMPs-L. SEM was operated at 5 kV and a working distance of about 6 mm. Folder named “Figure-2c” three folders named “CMPs-L-25, CMPs-M-25, CMPs-S-25” have files for reflectance data of white films made of CMPs-L, CMPs-M, and CMPs-S at the same thickness of 25 μm and ff = 25%, measured with an integrating sphere. Folder named “Figure-2d” has angular distribution data for CMPs-L films with two different thickness, which was recorded using a goniometer. The illumination angle was fixed at normal incidence and the angular distribution of intensity was acquired by rotating the detector arm around the sample with a resolution of 1°.

Folder named “Figure-3” has seven folders: folder named “Figue-3a” has a photograph (taken by a regular camera) of a high optical haze film (with 20% of CMPs-XL) on the background of a paper with printed letters. Folder name “Figure-3b” has a SEM image of the surface of a composite film with 20% CMPs-XL. SEM was operated at 5 kV and a working distance of about 6 mm. Folder named “Figure-3c” has a MATLAB data for transmittance and haze spectra of a composite film with 20% CMPs-XL, measured with an integrating sphere. Folder named “Figure-3d” has angular distribution data for the intensity (wavelength = 400 nm) transmitted through films (20% CMPs-XL and 30% CMPs-XL) made of CMPs-XL by goniometer measurement. Folders named “Figure-3f, Figure-3g” have the original pictures of transparent and haze films with laser passing through them, respectively.

Folder named “Figure-S-1” has a PPT file for the Schematic drawing for the experimental setup for haze measurements.

Folder named “Figure-S-2” has four excel files: width and length data for CMPs-S, CMPs-M, CMPs-L, and width and length data for haze fibers (CMPs-XL), respectively, data measured from STEM images.

Folder named “Figure-S-3” has simulated data for scattering strength of a Mie-Sphere plotted against the size ratio (radius/wavelength) according to Mie theory.

Folder named “Figure-S-4” has a folder named “Polar plots” with nine txt data files, for the numerical, three-dimensional, simulations of the single-particle properties of CMPs. Numerical FDTD simulations of the optical response of the generated structures were performed in Lumerical.

Folder named “Figure-S-5” has three txt files, one for optical simulations of scattering cross-section of traditional CNCs. Another two files for angular distribution of the scattered light (differential scattering cross section) for traditional CNCs. Numerical simulations of the optical response of the generated structures were performed in Lumerical.

Folder named “Figure-S-6” has a ppt file for the schematic drawing of the vacuum process of fabrication of free-standing films from cellulose particles.

Folder named “Figure-S-7” three folders: folder named “S7a” has a ppt file for the schematic drawing for the process for hydrophobic treatment of CMPs-L, and the formation a of films which were directly dried in the air. Folder named “S7b” has one SEM image of the cross-section of the hydrophobic CMPs-L films, and one image of the contact angle profile of water droplet on the surface of hydrophobic CMPs-L film. Folder named “S7b-spectra” have Matlab files for the data of reflectance of the hydrophobic CMPs-L films measured with an integrating sphere.

Folder named “Figure-S-8” has two folders: folder named “Figure-S8a and b” which has three folders, named “one, two, three-four”, they have MATLAB data for total transmission data for CMPs-L samples with ff=0.4 and different thickness (10, 15, 20 and 30 μm) measured with an integrating sphere, respectively. Folder named “Figure-S8c” has the data for the spectral dependency of the transport mean free path.

Folder named “Figure-S-9” has six folders: folder named “a, b, c, d” each has a SEM image for the cross-section of white films made of CMPs-L with ff=53% and thickness of 9 μm, and CMPs-L, CMPs-M, CMPs-S with the same thickness of 25 μm. SEM was operated at 5 kV and a working distance of about 6 mm. Folder named “e” has a MATLAB file for reflectance of white films made of CMPs-L with the thickness of 9 μm at ff=53% and 40%, measured with an integrating sphere. Folder named “f” has three MATLAB files of scan data (scan-1, scan-2, and scan-3), which provide the original white plot data for the films with two different filling fractions but at the same thickness, and also three data set for the film of L-CMP, M-CMP and S-CMP, all these have been descripted in the text file named “indication for white plot” and measured with an integrating sphere (Labsphere), each spectrum was recorded using an integration time equal to 3 s.

Folder named “Figure-S-10” has the simulated optical response data for the ensemble of CMPs-L, M, S with different filling fractions, and with various length and diameter.

Folder named “Figure-S-11” has a regular camera picture for a pure CMC film.

Folder named “Figure-S-12” has two folders “S12-1, S12-2” containing MATLAB data for total light transmittance and haze values of films with different content of CMPs-XL. All data were measured with an integrating sphere.

Folder named “Table-1” has two folders, containing the data for the dimensions of CMPs-S, CMPs-M, CMPs-L, and CMP-XL. Folder named “Thickness” has six SEM images of the cross section of the films for measuring the thickness of these four types of particles. Folder named “Length-Width” has four excel files with data for the width and length of these four types of CMPs, data were obtained with STEM, and these STEM images were shown in the four folders named “Figure -1a, 1b, 1c, 1d”.

Folder named “Table-2” has five folders, folder named “CMPs-L about 9 um” has a MATLAB file for total transmission data for CMPs-L films with 40% and 53% filling fraction at 9 μm in thickness, measured with an integrating sphere. Folders named “CMPs-S-25um, CMPs-M-25um, CMPs-L-25um” have MATLAB files for total transmission data for films made of CMPs-S, CMPs-M, CMPs-L at 25 μm thickness, measured with an integrating sphere.