6.3.4.3　Emulsion cross-linking method

It refers to the method that the polymer is cross-linked after the formation of stable nano-emulsion，so that the polymer forms a three-dimensional network structure in the droplet and the droplets of nano-emulsion are transformed into nano-gel consequently.According to the solubility of the polymer，oily nano-gels can be prepared by emulsion crosslinking method and aqueous nano-gels are able to be prepared by reverse emulsion crosslinking method.The cross-linking agents can be added to the droplets in advance.After the formation of the nano-emulsion，the cross-linking reaction can be initiated by external stimuli（e.g.，temperature，pH，light）.For non-stimulus responsive cross-linking agents，they can be added into the continuous phase after the emulsion is formed and the polymer is crosslinked via the diffusion of cross-linking agents into the droplet.Like cross-linking nanoprecipitation method，there are physical-cross-linking method and chemical-cross-linking method.(https://www.daowen.com)