水凝膠薄膜因其獨特性質在各種應用中展現出潛力；然而，對於其在形變過程中微觀結構演化及力學行為的微觀理解仍不明確。本研究採用耗散粒子動力學模擬，並整合了化學鍵斷裂機制，以探討化學交聯水凝膠薄膜在單軸拉伸下的應力鬆弛與多週期彈性遲滯現象。儘管模擬的宏觀響應與實驗觀察結果在性質上一致，我們仍系統性地監測了諸如化學鍵長度、鏈段伸長、內能變化以及化學鍵斷裂等微觀量。在中等應變下，應力鬆弛現象並不明顯，但在大應變時則變得顯著。此外，與應力相似，微觀量也表現出顯著的遲滯行為。我們的分析顯示，應力鬆弛和彈性遲滯現象的主要原因均為高度拉伸化學鍵的極少數斷裂，以及隨後的網絡結構重排。此種化學鍵層面的微觀演化主導了材料的宏觀力學行為—尤其是在大應變下，極少數的化學鍵斷裂是由熱擾動所驅動，使得拉伸鍵能夠克服因應變而降低的能壘;Hydrogel films exhibit promising potential across various applications due to their unique properties; however, a microscopic understanding of their microstructural evolution and mechanical behavior under deformation remains elusive. This work employs dissipative particle dynamics simulations, which incorporate bond rupture, to investigate stress relaxation and multi-cycle elastic hysteresis in chemically crosslinked hydrogel films under uniaxial stretching. While the simulation’s macroscopic responses are qualitatively consistent with experimental observations, microscopic quantities—such as bond length, strand extension, internal energy changes, and bond rupture—are systematically monitored. Stress relaxation is absent under moderate strain but becomes significant at large strain. Additionally, similar to stress, microscopic quantities exhibit pronounced hysteresis behavior. Our analysis reveals that the primary cause of both stress relaxation and elastic hysteresis is the rare rupture of highly stretched bonds, followed by network structural rearrangement. This bond-level microscopic evolution governs the material’s macroscopic mechanical behavior—particularly under large strains, where rare bond rupture is driven by thermal fluctuations that enable tensile bonds to overcome strain-reduced energy barriers.
