Table 2.

Advantages and disadvantages of physical cross-linking and chemical cross-linking technology.

Types of Cross-Linking	Advantages	Disadvantages	Refs
Physical cross-linking (Non-permanent)	(1)The synthesis principle is a physical action, which is relatively simple; (2)No need to use toxic cross-linking agents; (3)The method can be improved according to the actual situation to improve the properties of the hydrogel.	(1)The resulting hydrogels generally have poor mechanical properties; (2)There may be uneven swelling distribution; (3)The number of components that can be cross-linked is limited	[1,76,77,78]
Chemical cross-linking (Permanent)	(1)The resulting hydrogels are generally structurally stable and have good mechanical properties; (2)Unlimited number of components that can be cross-linked; (3)It has substrate specificity, keeps effective reactions continuous, and avoids ineffective reactions; (4)“Click chemistry” has high efficiency, stability, high specificity, and high control, and it meets molecular diversity requirements.	(1)Toxic crosslinking agents are required in the chemical cross-linking process; (2)There may be uneven swelling distribution; (3)Chemical cross-linking is not all controllable.	[1,78,79,80,81]