Poly(tert-butyl acrylate)-b-poly(N-isopropylacrylamide) (PtBA-b-PNIPAM) was first synthesized by sequential reversible addition-fragmentation chain transfer polymerization of tert-butyl acrylate and N-isopropylacrylamide. Its hydrolysis led to amphiphilic poly(acrylic acid)-b-poly(N-isopropylacrylamide) (PAA-b-PNIPAM) that can form micelles in aqueous solutions at temperatures higher than 37 degrees C because PNIPAM is a thermally sensitive polymer. In the presence of Ca2+, the complexation between one Ca2+ and two COO- groups on different PAA blocks can induce the chain association. Using a combination of static and dynamic laser light scattering, we studied the effect of Ca2+ and temperature as well as the sequence of adding Ca2+ ions and heating the solution on such association. We found that (1) the association is controllable and reversible, (2) a distinct hysteresis is observed between the heating and cooling processes, (3) the time evolution of the average aggregation number (N-agg) and the average hydrodynamic radius ((R-h)) of the aggregates can be expressed by a single-exponential equation, (4) the aggregates have a fractal dimension of 1.5-1.9, suggesting a diffusion-limited process, and (5) adding Ca2+ before heating result; in the aggregates with a more open and looser structure. The current study provides a model system to investigate a more complicate problem, namely, the effect of metal ions on the stability of protein chains.