Polymer topology dictates dynamic and mechanical properties of materials. For most polymers, topology is a static characteristic. In this article, we present a strategy to chemically trigger dynamic topology changes in polymers in response to a specific chemical stimulus. Starting with a dimerized PEG and hydrophobic linear materials, a lightly cross-linked polymer, and a cross-linked hydrogel, transformations into an amphiphilic linear polymer, lightly cross-linked and linear random copolymers, a cross-linked polymer, and three different hydrogel matrices were achieved via two controllable cross-linking reactions: reversible conjugate additions and thiol−disulfide exchange. Significantly, all the polymers, before or after topological changes, can be triggered to degrade into thiol-or amine-terminated small molecules. The controllable transformations of polymeric morphologies and their degradation herald a new generation of smart materials.

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This study examines how structural aspects of online brand communities can contribute to the brand building capacity of the community using network theory. Predictions about the degree to which various structural factors are associated with emotional attachment to the community and other outcome measures are made. Results show that several structural characteristics play an important role in creating emotional attachment and contributing to relationship maintenance. Thus, the fi ndings support the use of network theory for understanding how brand communities operate. It is also found that certain structural factors have Lee et al

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