## 3 Results  
### Physicochemical Properties of Natural and Synthetic Cosmetic Emollients  
#### 3.1.1 Spreading Properties of Cosmetic Emollients  
The spreading properties of raw materials and cosmetic products can be defined as their ability to cover the skin faster or slower [1]. The speed of the spread of raw materials depends on many factors, including density, dynamic viscosity, and surface tension. Therefore, in the first stage of the research, the features that affect the ability to spread natural and synthetic emollients were determined using instrumental analysis (density, viscosity, and surface tension). Figures 1-3 show the physicochemical properties of natural and synthetic/semisynthetic cosmetic emollients. Significant differences in dynamic viscosity (\(\eta\)) can be observed between the tested raw material samples. Dibutyl Adipate and Dicaprylyl Carbonate are characterized by the lowest viscosity value among the tested synthetic emollients, amounting to approximately 18-21 mPa-s. In turn, Octyldodecanol has the highest \(\eta\) value (114 mPa-s), which is over six times higher than the least viscous, Dibutyl Adipate. Unlike the results of measuring the dynamic viscosity of synthetic emollients, the results of measuring the viscosity of natural emollients do not differ significantly from each other. Among the tested vegetable oils, grape seed oil and sweet almond oil are characterized by the lowest viscosity values, 74.2 and 86.8 mPa-s, respectively. In turn, the highest \(\eta\) value among the tested natural oils  
Figure 1: Dynamic viscosity of cosmetic emollients. **(A)**—natural emollients; **(B)**—synthetic/semisynthetic emollients; Natural emollients: MTSO—_Macadamia Tentifolia Seed Oil_, PADO—_Prunus Amygdala Dulcis (Sweet Almond) Oil_, RCSO—_Ricinus Communis (Castor) Seed Oil_, VVSO—_Vitifena (Grape) Seed Oil_. Synthetic/semisynthetic emollients: CCTG—Caprylic/Capric Triglyceride, DA—Dibutyl Adipate, OD—Octyldodecanol, DC—Dicaprylyl Carbonate; ***—significance level \(p<0.001\), ***—significance level \(p<0.0001\). was recorded for macadamia nut oil, which is 39 mPa-s more viscous than the least viscous grape oil. The density of synthetic emollients Octyldodecanol and Dicaprylyl Carbonate is 0.841 and 0.843 g/cm\({}^{3}\), respectively. Caprylic/Capric Triglyceride and Dibutyl Adipate have higher density values, with the highest density among synthetic emollients observed for Dibutyl Adipate--0.962 g/cm\({}^{3}\). No impact denoted the type of natural emollients  
Figure 3: Surface tension of cosmetic emollients. (**A**)—natural emollients; (**B**)—synthetic/semisynthetic emollients; Natural emollients: MTSO—_Macadamia Terrifolia Seed Oil_, PADO—_Prunus Amygdalus Dulcis (Sweet Almond) Oil_, RCSO—_Ricinus Communities (Castor) Seed Oil_, VVSO—_Vitis Vinifera (Grape) Seed Oil_. Synthetic/semisynthetic emollients: CCTG—_Caprylic/Capric Triglyceride, DA—Dibutyl Adipate, OD—Octyldodecanol, DC—Dicaprylyl Carbonate; ****——significance level \(p<0.001\), ****–significance level \(p<0.0001\). Figure 2: Density of cosmetic emollients. (**A**)—natural emollients; (**B**)—synthetic/semisynthetic emollients; Natural emollients: MTSO—_Macadamia Terrifolia Seed Oil_, PADO—_Prunus Amygdalus Dulcis (Sweet Almond) Oil_, RCSO—_Ricinus Communis (Castor) Seed Oil_, VVSO—_Vitis Vinifera (Grape) Seed Oil_. Synthetic/semisynthetic emollients: CCTG—_Caprylic/Capric Triglyceride, DA—Dibutyl Adipate, OD—Octyldodecanol, DC—Dicaprylyl Carbonate; ****–significance level \(p<0.001\). on the density of this type of raw materials. Castor oil has the highest density value (0.964 g/cm\({}^{3}\)) compared to the other tested vegetable oils. Grapeseed oil, sweet almond oil, and macadamia nut oil are characterized by comparable density results, within margins of error, ranging from 0.916-0.924 g/cm\({}^{3}\). Surface-tension values for natural emollients ranged from 31.6 to 37.1 mN/m, with the highest value observed for castor oil and the lowest for macadamia nut oil.