A series of shape memory polyurethanes were synthesized from poly(tetramethylene glycol), 4,4-methylene diphenyl diisocyanate, and 1,3-butanediol. The prepolymers with different molecular weights (Mc) were capped with 2-hydroxyl ethylacrylate or 3-aminopropyltriethoxysilane (APTES) and crosslinked by UV curing or a sol-gel reaction. Variations of the crosslinker functionality (f), subchain density (N), and hard segment content (HSC) produced systematic variations of the glass transition temperature (6-45 degrees C), accompanied by changes in the mechanical, dynamic mechanical and shape memory properties. More than 95% of shape fixity and 98% of shape recovery up to the fourth cycles were obtained with APTES crosslinked 3000Mc with 30% of HSC. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1473-1479