We have recently developed two novel types of nanostructured polymer systems that have unique properties resulting from their nanostructured nature. The first is nanostructured polymer system is a compatibilized immiscible polymer blend in which the dispersed-phase domains are ~100 nm in diameter. These materials can be made using conventional melt processing methods but require the use of special compatibilizing agents which will be described in detail in the presentation. When polystyrene (PS)/poly(ethylene oxide) (PEO) blends are made with 100 nm diameter PEO domains, a major change in crystallization behavior in observed in the PEO domains relative to bulk PEO. Instead of undergoing heterogeneous nucleation when cooled from high temperature to a temperature above but near room temperature as in the case of bulk PEO, the nanoscale dispersed domains of PEO in PS only crystallize homogeneously at temperatures well below 0 degrees Celsius. Thus, the nanostructured PS/PEO blends that are maintained at temperatures near or above room temperature have a glassy matrix with nanoscale rubbery domains dispersed in the matrix. Normally, PS/PEO blends would consist of a glassy matrix with semicrystalline microscale domains of PEO, which have properties different from those of the nanostructured blends. The second type of novel nanostructured polymer system is a gradient copolymer, which is made of two monomer types, A and B, with a gradient in composition along the chain length from mostly A units on one end to mostly B units on the other ends. These materials formed nanoscale ordered states similar to those block copolymers but with sinusoidal composition profiles rather than square wave composition profiles commonly observed with block copolymers. As a result, nanoscale-ordered gradient copolymers can exhibit unique thermal properties with extremely broad glass transition temperatures, as much as 100 K in breadth.