As one of the most widely used silicone polymers, polydimethylsiloxane (PDMS) microgel particles have broad application prospects in the fields of sensors, polymer toughening agents, bioengineering, and drug delivery. Here, we reported the continuous preparation of homogeneous crosslinked PDMS microgel particles through photoinduced reversible addition-fragmentation chain transfer (photoRAFT) polymerization. Based on the design of methacrylate-functionalized PDMS, the introduction of photoRAFT polymerization allows the formation of microgel particles with homogeneous networks, which were more regular and have better swelling behavior than networks prepared by conventional free radical polymerization processes. Moreover, the dormant polymer chain could be reactivated and lead to the postmodification of PDMS microgel particles. The crosslinking RAFT polymerization was continuously carried out in a flow photoreactor. Uniform PDMS microgel particles with high colloidal stability could be achieved in a short time (0.5–10 min), and the crosslinking densities can be easily tuned by changing the residence time which has less effect on the final particle size.
Yi Wang,Jinrong Wu,Zhenxing Cao,Changshu Ma,Qingbo Tong,Jiangbo Li,Hanchao Liu,Jing Zheng,Guangsu Huang
Designing a homogeneous network is an efficient way to improve the mechanical properties of hydrogels. However, the homogeneous hydrogels usually have negligible notch-insensitivity due to the lack of effective energy dissipation, limiting their practical applications in many fields. Herein, we provide a straightforward method to prepare a category of tough and notch-insensitive polyacrylamide hydrogels crosslinked by a novel cross-linker with multiple vinyl functional groups (TA). Due to the multifunctionality of TA , a relatively uniform network with the coexistence of physical cross-links is constructed by the steric effect between chain radicals on TA molecules during the polymerization. The uniform network distributes stress evenly while the physical cross-links lead to viscoelastic dissipated energy under external force. As a result, the hydrogels achieve an ultrastretchability of 2400% and a tensile toughness of 4.33 MJ/m 3 . Even with a notch of 10 mm, the hydrogels can still be stretched to a strain of 20, indicating an impressive notch-insensitivity. Meanwhile, the hydrogels exhibit high fatigue resistance and good self-recovery. This research offers a facile strategy for designing high-performance hydrogels and may pave the way for their practical application in emerging fields, such as oil displacement agent and artificial cartilage .
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