Large area crystal surfaces of precisely side branched polyethylenes : preparation surface order and functionalization Zusammenfassung: Upon crystallization of polymers containing precisely spaced side branches the side branches are excluded from the crystalline core of the lamellar crystal. Thus the surfaces of these crystals are covered by side branches. By using carboxyl groups as side branches which can be ionized in aqueous environments self stabilized nanocrystal dispersions can be prepared. In principle the carboxyl groups also allow for the covalent attachment of functional molecules to the lamellar crystals using well established strategies for amide bond formation. However the fold surfaces of the crystals need to be highly ordered so that the carboxyl groups are accessible for functionalization.From x ray scattering in semicrystalline bulk we found that precisely spaced side groups do not predefine the thickness of the crystalline core under all crystallization conditions. In addition the part of the fold layer containing carboxyl groups had a considerable thickness indicating that there is a substantial disorder in the fold surfaces of lamellar crystals of polymers containing precisely spaced side branches