Adjacent reentry of folded polydimethylsilane polymer chains

How does the polymer chain fold when polymer single crystals are grown? Evidence from AFM images of the surface structure of polydimethylsilane crystals is presented that suggests the adjacent recently model, in which the chains are regularly folded. Making hairpin turns at the surface (see Figure), describes the process better than the random (switchboard) model, in which an amorphous overlayer is produced. magnified image