Why is amylose insoluble in water?
The availibity of -OH groups for hydrogen bonding with polar water molecules is reduced in amylose due to its coiled nature (resulting in part by H-bonds between the glucose monomers).  Amylopectin is even less soluble due to the additional 1-6 glycosidic bonds on the branch chains, further reducing its H bonding potential and therefore reducing solubility in water.