Copolymer hydrogels formed from cationic and aromatic monomers with identical monomer compositions but different average sequences were synthesized by free-radical copolymerization in various solvents. We found that hydrogels with one-componentrich segments are mechanically stronger than those with adjacent-rich monomer sequences in water, while hydrogels with a rich cation-π adjacent sequence showed excellent mechanical strength and underwater adhesion in saltwater (0.7 M NaCl). The molecular mechanisms for these behaviors are discussed in terms of polymer structures. This work reveals the importance of monomeric sequences in determining hydrogel properties and provides a facile approach to develop hydrogels with different properties but the same monomer composition.

This study evaluated the impacts of tin and amino-functional silane on the long-term durability of a silicone coating material. An experimental design was applied. Tin and aminosilane's concentrations were the variables. Laboratory-made samples were tested for initial mechanical properties. Samples were further placed in the QUV accelerated weathering chamber (fluorescent UV and condensation method) and tested periodically for tensile and elongation properties within the durability evaluation. Based on the observations of the material and the measurements of mechanical properties, the concentration of tin in the formulation has the most influential impact on durability. The higher the concentration of tin, the faster the chalking. The concentration of the aminosilane also showed similar impacts on the durability, but not as significant as tin. This study suggested that it is feasible to reduce both tin and aminosilane's amount by 30 % without significant impacts on the material's properties, and this may improve the coating's durability by more than 50 %. This finding may also apply to silicone sealant and adhesives.