Recently,a passive chain embedded in a fluid of active Brownian particles(ABPs),which can bring a non-equilibrium fluctuation to the chain,has been st.udied by various computer simulations,which found significant conformational changes of the chain because of the active environment.1,2 ABPs are inherently non-equilibrium,consuming energy to produce motion.3 They can generate the spatially varying mechanical pressure on chains.For example,a temporarily stable hairpin conformation of semi-flexible chain was found in the ABP bath and the chain fluctuates between hairpin and stretch states in time.It implied that the ABPs can be utilized to manipulate chain conformations.We study the structural and dynamical behaviors of a diblock chain in a bath of ABPs by extensive Brownian dynamics simulation in a two-dimensional model system.Specifically,the A block of chain is self-attractive,while the B block is self-repulsive.We find,beyond a threshold,the A block unfolds with a pattern like extracting a woolen string from a ball.The critical force decreases with the increase of the B block length(NB)for short cases,then keeps a constant with further increase of NB.In addition,we find a power law exists between the unfolding time,tuf,of chain and active force,Fa,as well as NB with the relation tuf ∝ Fa-1.1 NB-1.34.Finally,we focus on the translational and rotational diffusion of chain,and find that both of them remain supper-diffusive at the long-time limit for small active forces due to an asymmetry distribution of ABPs.Our results open new routes for manipulating chains behaviors with ABPs.