1.3.7 Porosity
In this experiment, the porosity of the hydrogels was determined using the liquid displacement method. The basic principle is as follows: a dry sample is immersed in a liquid that can penetrate the pores of the material without causing swelling or chemical reactions. The porosity is calculated by measuring the change in mass of the sample before and after immersion in the liquid, which reflects the volume proportion of the internal pores. Known-volume and known-mass lyophilized samples (HG and Y-HG-1) were immersed in anhydrous ethanol for 24 hours, and excess ethanol on the surface was removed before weighing. The porosity (Porosity, P) was calculated using the following formula:
[ P = \frac{m_2 - m_1}{\rho V_0} \times 100% \quad \text{(1-2)} ]
where ( m_1 ) is the mass of the lyophilized sample, ( m_2 ) is the mass of the lyophilized sample after 24 hours of immersion in ethanol, ( \rho ) is the density of ethanol, and ( V_0 ) is the volume of the lyophilized sample.
