The confined space produced during the polymerization has access for all small organic molecules or oligomers with small size to enter this confined space; however, it can prevent the macromolecules with big size from entering. Therefore, the reaction between two branched macromolecules is excluded in A(2) + B-3 polymerization system, resulting uncrosslinked branched polymers, and there was no gel point observed throughout the polymerization. (c) 2008 Wiley Periodicals, Inc.