Functional van der Waals layered materials, which exhibit interesting phenomena such as magnetism and ferroelectricity, have been proposed for use in next-generation nanoscale devices and sensors. $\mathrm{CuCr}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$ is a promising two-dimensional (2D) material that evinces multiferroic behavior where the $\mathrm{C}{\mathrm{u}}^{+}$ and $\mathrm{C}{\mathrm{r}}^{+3}$ cations are responsible for antiferroelectric and antiferromagnetic ordering, respectively. In this study, we use x-ray diffraction and Raman spectroscopy to map out these phase transitions in the range 70--400 K. The antiferroelectric phase transition is complex and shows a gradual transition to complete antipolar order with an intermediate quasiantipolar step. X-ray diffraction studies reveal evidence for negative thermal expansion across the antipolar phase transitions at \ensuremath{\sim}270 and \ensuremath{\sim}140 K. The latter of these is accompanied by a drastic reduction in rotational and translational mode frequencies of the anion groups in $\mathrm{CuCr}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$. Our temperature-dependent structural data provide an important reference for subsequent research into this promising 2D multiferroic material.