Rigid-Flexible Synergy in Hydroxyethyl Cellulose-Polyurethane Composites Featuring Dynamic Disulfide Bonds for Highly Efficient Self-Healing

Cellulose is a green and renewable biobased material with immense potential, yet its application in self-healing materials is hindered by its inherent rigidity, which severely limits the molecular chain movement. To break through this limitation, we introduce an innovative design strategy: “Introduces a rigid-flexible synergy strategy by utilizing the flexible polymer network to drive the rigid cellulose network”. In this strategy, a hydroxyethyl cellulose-based composite material with a synergy network structure was successfully constructed by covalently bonding a rigid hydroxyethyl cellulose (HEC) backbone into a flexible polyurethane (PU) matrix containing dynamic disulfide bonds. The inherent thermodynamic incompatibility between HEC and the PU matrix leads to the formation of HEC-rich rigid domains that act as multifunctional cross-linking points, enhancing the mechanical integrity of the material. Upon damage, the high mobility of the flexible PU segments, coupled with the dynamic exchange of disulfide bonds, allows the entire network to rearrange and flow at the crack interface, leading to highly efficient healing. The anchored HEC domains provide structural stability during this process. The results show that the composite material not only maintains excellent mechanical properties but also achieves a self-healing efficiency of up to 96.6%, which is 3.7 times higher than that of the control group without disulfide bonds. Furthermore, this composite possesses outstanding thermal reprocessability. This research carves out a new path for high-performance hydroxyethyl cellulose-based smart materials and offers a promising material-based solution to tackle plastic pollution and advance sustainable development goals.