Block copolymers(BCPs) have been attracting significant attentions owning to their wide industrial applications such as elastomer materials, optics, electronics, information, chemistry and biology in the past decades. The unique properties and materials performances of BCPs arise from their rich nanostructures. The chemistry difference between covalently bonded blocks leads to microphase separation and characteristic nanosized domains, which is a function of temperature, block composition and the degree of polymerization of blocks. The consequent self-assembly behavior displays rich ordered morphologies, which typically include sphere, cylinder, gyroid and lamellae. Among the mesostructures, network morphologies are especially interesting and useful because of their three-dimensionally co-continuous, interpenetrated meso-networks. Their character of high porosity and huge interface area generates practical merits in various applications such as outstanding mechanical anti-creep and high charge transport efficiency of optoelectronic devices.However, the rarely observed network morphologies of BCPs gain insufficient attentions. This review introduces fundamental principles of BCPs self-assembly and emphasizes the network morphologies of diBCPs. Three main types of network morphologies are discussed, including ordered bicontinuous double diamond (OBDD), double gyroid (DG) and Fddd. It also reviews three kinds of network preparation methods that appear in recent literatures: precise synthesis of diBCPs with specific chemistry, order-order phase transition from other nanostructures, and blending with homopolymer. Several typical applications are also reviewed. In the last part, the current research highlights are summarized and the future research directions of network mesosturctures are predicted.

Contents
1 Introduction
2 Self-assembly of diblock copolymers
2.1 Block copolymers
2.2 Self-assembly principles of diblock copolymers
2.3 Network morphologies
3 Preparation methods of network mesostructures of diblock copolymers
3.1 Precise synthesis
3.2 Order-order transition
3.3 Blending
4 Applications
5 Conclusion