A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)-block-poly(ethylene oxide)-block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. PESn[Co2(CO)6]x-EO800-PESn[Co2(CO)6]x ABA triblock copolymer/cobalt adducts (10-67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co2(CO)8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linked materials with water. Swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors.

The thermal response of semi-dilute solutions (5 w/w%) of two amphiphilic thermoresponsive poly(ethylene oxide)-b-poly(N,N-diethylacrylamide)-b-poly(N,N-dibutylacrylamide) (PEO -PDEAm -PDBAm ) triblock copolymers, which differ only in the size of the central responsive block, in water was examined. Aqueous PEO -PDEAm -PDBAm solutions, which undergo a thermally induced sphere-to-worm transition in dilute solution, were found to reversibly form soft (G'≈10 Pa) free-standing physical gels after 10 min at 55 °C. PEO -PDEAm -PDBAm copolymer solutions, which undergo a thermally induced transition from spheres to large compound micelles (LCM) in dilute solution, underwent phase separation after heating at 55 °C for 10 min owing to sedimentation of LCMs. The reversibility of LCM formation was investigated as a non-specific method for removal of a water-soluble dye from aqueous solution. The composition and size of the central responsive block in these polymers dictate the microscopic and macroscopic response of the polymer solutions as well as the rates of transition between assemblies.

The mechanical properties of a new type of nanocomposite gel, consisting of varying concentrations of the biopolymer alginate and the synthetic clay Laponite®, together with the temperature-sensitive copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, trade namePluronic®F127), are reported. These "ALP" gels (alginate-Laponite®-Pluronic®) were prepared and studied using rheology. Gels with multiple networks and gelation mechanisms have been exploredas one strategy to strengthen and stiffen conventional hydrogels, which usually consist of a single polymer network. This work shows that the ALP gels exhibit significantly higher storage and loss modulus (G', G") values than gels composed of only alginate and Laponite®. Moreover, the interaction between the components appears to be synergistic; that is, the resulting multicomponent hydrogels are much more elastic than the additive effects of individual components. For example, the G' of one series of the nanocomposite gels containing F127 Pluronic® experiences two orders of magnitude enhancement compared to its respective control containing only alginate and Laponite®. Furthermore, the ALP gels show a 20-40x enhancement in storage modulus, with values as high as 10,000-20,000 Pa, over the 30-55°C temperature range.The large degree of enhancement in the storage modulus of the ALP gels with addition of Pluronic® is quite remarkable, compared to alginate-Laponite® gels on their own at comparable concentrations and temperatures, which form relatively weak gels. These results provide a simple strategy for significantly increasing the mechanical properties of polymer hydrogels used in biomaterials applications.

The thermal response of semi-dilute solutions (5 w/ w%) of two amphiphilic thermoresponsive poly(ethylene oxide)-b-poly(N,N-diethylacrylamide)-b-poly(N,N-dibutylacrylamide) (PEO 45 -PDEAm x -PDBAm 12 )triblock copolymers, which differ only in the size of the central responsive block, in water was examined. Aqueous PEO 45 -PDEAm 41 -PDBAm 12 solutions,whichundergo athermally induced sphere-to-worm transition in dilute solution, were found to reversibly form soft (G' % 10 Pa)f ree-standing physical gels after 10 min at 55 8 8C. PEO 45 -PDEAm 89 -PDBAm 12 copolymer solutions,w hich undergo at hermally induced transition from spheres to large compound micelles (LCM) in dilute solution, underwent phase separation after heating at 55 8 8Cfor 10 min owing to sedimentation of LCMs.T he reversibility of LCM formation was investigated as an on-specific method for removal of aw atersoluble dye from aqueous solution. The composition and size of the central responsive block in these polymers dictate the microscopic and macroscopic response of the polymer solutions as well as the rates of transition between assemblies.Supportinginformation, includinge xperimental details, and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.