Synthesis of acrylic resin and methacrylic resin microspheres by suspension polymerization

The process of suspension polymerization was utilized to create acrylate resin microspheres with mesh numbers of 140–200 μm and particle sizes of 100 μm for implementation in mesh coating technology. The copolymer of methyl methacrylate (MMA) and methyl acrylate (MA) served as the primary polymer, with dibenzoyl peroxide (DBPO) functioning as the initiator, and a mixture of calcium carbonate and deionized water served as the dispersion medium. The surface morphology of the synthesized microspheres was analyzed through Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) to confirm successful synthesis. The optimal reaction conditions for the synthesis of these microspheres were determined to be a dispersant dosage of 30 g of calcium carbonate with a monomer ratio of 4:1, a reaction time of 1 h, an initiator dosage of 1.2 g of BPO, and a reaction temperature of approximately 75–80 C, resulting in microspheres with a regular spherical shape and smooth surface.

. Suspension polymerization product synthesis equation

Chemicals and instruments
Methyl methacrylate (analytical grade) was purchased from the Tianjin Zhiyuan Chemical Reagent Co., Ltd.; Methyl acrylate (analytical grade) was purchased from the

Experimental method
Step 1: Blending MMA and MA, followed by the addition of BPO and thorough mixing.
Step 2: First, in three beakers, add CaCO3 and deionized water, and mix while heating to 60°C, allowing CaCO3 to fully dissolve. Next, add the pre-processed MMA and MA mixture, and with deionized water rinse the MMA and MA flask, and add the entire contents to the three beakers. Heat the mixture to 75°C, adjust the mixing speed, and maintain a constant mixing speed for approximately 1 hour. Then, withdraw a small amount of bead-like precipitate using a dropping tube, and allow it to cool in water. If it does not harden, continue the reaction while adjusting the mixing speed to slow down the reaction, allowing the single species to fully react. If it hardens, increase the temperature to speed up the hardening process, and heat the mixture to 80°C, reacting at a constant speed for 3 hours.
Step 3: Transfer the product to a large flask, cool, and allow the supernatant to be decanted. Add HCl (10%) and mix, adjusting the pH to 1-1.5.
Step 4: Separation and drying of the polymer: Repeat the addition of cold deionized water three times to wash the precipitated polymer, and then filter. Dry the filtered polymer in an oven at a temperature of 70°C for 6 hours.

Modulate the reaction parameters to investigate their influence on the product formation
In this experimental study, an exhaustive examination of the reaction conditions was undertaken by manipulating parameters such as temperature, time, the calcium carbonate concentration, the molar ratio of MMA to MA, the type and concentration of initiator, and the amount of initiator [1] . for the initiator of this experiment [2][3][4][5] .

Productivity
Weigh and calculate the yield, and observe the shape, color, and transparency of the polymer.

Sieving
Mesh number reflects the particle size, and as the mesh number increases, the particle size decreases. In the characterization of small aggregated particles of a fine powder, the mesh number is commonly used to represent the size of the particles.

Fourier transform infrared spectroscopy analysis
The potassium bromide and the sample were formulated into a tablet at a ratio of 200:1, and subsequently introduced into the infrared measurement apparatus, where the computer parameters were adjusted for analysis. By comparing the chemical bonds of the molecules, corresponding to the characteristic peaks in the infrared spectrum, with the polymer components, the polymer structure was examined.

Analysis of polymer microtopography
The polymer microspheres were subjected to a series of processing steps and subsequently positioned under the electron microscope for visual inspection [6,7] .

Molecular weight characterization
We employed the Number-average molecular weight (Mn), weight-average molecular weight (Mw), Z-average molecular weight (Mz), Peak molecular weight (Mp) to characterize the polymer's Relative molecular mass [8,9] . The corresponding molecular weight equations for each type of molecular weight are as follows: (Polydisperse polymer) [8,9] .

Skin sensation testing
Following the completion of the preparation, the polymer exhibiting optimal reactivity was subjected to dyeing. Eight individuals were conscripted for a blind test to evaluate the efficacy of nails fabricated from the polymer, encompassing aspects such as smoothness after application, spread of application, irritation, greasy sensation, and overall skin feeling liking degree. The score was calculated as the mean value of all participants, with a lower score indicating a less favorable outcome. Subjectively, a digitized five-point scale was utilized to assess the personal skin sensation, with a lower value corresponding to an increasingly unfavorable sensation.  In Figure S3, the x-axis represents the molecular weight, with the blue line depicting the proportion of the different molecular weights in the test sample, with the corresponding coordinates on the left side. The y-axis displays the proportion of these macromolecules. It is evident that the proportion of macromolecules in the sample with molecular weights within the range of 2.5e5 (Mw = 2.5*10 5 g/mol) is the highest. The red line represents the cumulative distribution, with the corresponding coordinates on the right side. Let the horizontal axis of the plot be labeled as 1*10 6 g/mol, with the vertical axis showing the proportion of macromolecules in the sample that fall within the molecular weight range of 0 g/mol to 1*10 6 g/mol. It is evident that as the horizontal axis moves further to the right, the variety of macromolecular species increases, and their proportion approaches 100%.