Contents

22 February 1991
Vol 251, Issue 4996

About The Cover

Small-angle neutron scattering pattern obtained from a diblock copolymer after the application of an oscillatory shearing deformation. The hexagonal symmetry of the scattered neutrons derives from the long-range ordering of cylindrical microdomains (see p. 898). This issue of Science focuses on the physics and chemistry of polymers. [Data and image by K. Almdal, K. Mortensen, and F. S. Bates at the Riso National Laboratory in Denmark]