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Biomedical subjects

Ingo Berndt

Publications and source records attributed to Ingo Berndt.

4 recordsLinked to original sources
PubMed2006

Influence of shell thickness and cross-link density on the structure of temperature-sensitive poly-N-isopropylacrylamide-poly-N-isopropylmethacrylamide core-shell microgels investigated by small-angle neutron scattering.

Swelling properties of doubly temperature sensitive core-shell microgels consisting of two thermosensitive polymers with lower critical solution temperatures (LCTS) at, respectively, 34 degrees C in the core and 44 degrees C in the shell have been investigated by small-angle neutron scattering (SANS). A core-shell form factor has been employed to evaluate the structure, and the real space particle structure is expressed by radial density profiles. By this means, the influences of both shell/core mass composition and shell cross-linker content on the internal structure have been revealed at temperatures above, between, and below the LCSTs. Higher shell/core mass ratios lead to an increased expansion of the core at temperatures between the LCSTs, whereas a variation of cross-linker in the shell mainly effects the dimensions of the shell. The influence on the core structure was interpreted as resulting from an elastic force developed from the swollen shell. At temperatures below the core LCST, the core cannot swell to its native size (i.e., in the absence of a shell), because the maximum expanded shell network prohibits further swelling. Thus, depending on temperature, the shell either expands or compresses the core.

Journal Article↗
PubMed2005

Structure of multiresponsive "intelligent" core-shell microgels.

A doubly temperature-sensitive core-shell microgel composed of two temperature-sensitive polymers with different lower critical solution temperatures (LCSTs) in the core and shell has been studied by small-angle neutron scattering (SANS). The application of a novel universal form factor model in the analysis of the SANS data reveals that the radial density profile at temperatures above the LCSTs of both polymers can be well described by a two-box profile with narrow interfaces. At temperatures between the LCSTs, the radial density profile reveals that the core in the core-shell microgel has larger dimensions than the naked core. Thus the swollen shell pulls the core apart. At temperatures below both LCSTs, however, the shell restricts the core swelling, and the core is found to be smaller than in its native state. This clearly demonstrates the mutual influence of core and shell swelling.

Journal Article↗