Polymeric Janus micro/nano-particles, which have anisotropic microstructures, can be widely applied in many fields, such as stabilizing emulsions, polymer mixing, controllable self-assembly, bio-medicines, heterogeneous catalysis and functional coatings. Therefore, the research on controlled fabrication and applications of polymeric Janus particles has been paid active attention in region of multifunctional and smart polymer materials. In this review, the progress of polymeric Janus particles in the past few years, such as synthetic strategies, stimulative responsibilities and applications, has been summarized. Their advantages and disadvantages have also been briefly discussed. The polymeric Janus particles with controllable sizes, microstructures and surface properties can be prepared via selective surface modifications, microfluidic synthesis, self-assembly, seed polymerization and other preparation strategies. However, the accurate fabrication and high yield of the particles in nanoscale are still a challenge. Stimulative responsibilities of polymeric Janus particles include pH-responsive property, temperature-responsive property, ion-responsive property, light-responsive property and other stimuli-responsive properties. Stimuli-responsive polymeric Janus particles possessing multicomponent structure have their special advantages in self-assembly and drug delivery. Seed polymerization as a simple and efficient strategy can be applied to prepare polymeric Janus surfactants in industrial production. The fabrication and applications of natural and multifunctional polymeric Janus particles are predicted finally as the development trends in the future.

Contents
1 Introduction
2 Synthesis strategies
2.1 Selective surface modifications
2.2 Microfluidic synthesis
2.3 Self-assembly
2.4 Seed polymerization
2.5 Other preparation strategies
2.6 Macromolecular Janus particles
3 Stimulative responsibilities
3.1 pH-responsive property
3.2 Temperature-responsive property
3.3 Ion-responsive property
3.4 Light-responsive property
3.5 Other stimuli-responsive properties
4 Applications
4.1 Solid surfactants
4.2 Building blocks
4.3 Bio-medicines
4.4 Janus films
4.5 Other applications
5 Conclusion