Volume transition and structure of triethyleneglycol dimethacrylate, ethylenglykol dimethacrylate, and N,N′-methylene bis-acrylamide cross-linked poly(N-isopropyl acrylamide) microgels: a small angle neutron and dynamic light scattering study

The influence of the cross-linker type on the swelling behaviour and the local structure of colloidal poly(N-isopropyl acrylamide) microgel particles is investigated by dynamic light scattering and small angle neutron scattering (SANS). The cross-linkers ethylenglykol dimethacrylate and triethyleneglycol dimethacrylate are found to form particles with larger swelling/de-swelling capacities compared to N,N′-methylene bis-acrylamide (BIS) cross-linked particles at identical cross-linker concentration. At low temperature the SANS spectra reveal similar values for the blob size, ξ, of the solution like domains in the three different networks. However, the temperature dependent scaling behaviour of ξ differs strongly between the BIS cross-linked and the other two species.