Diffusion of linear macromolecules and spherical particles in semidilute polymer solutions and polymer networks

详细信息    查看全文

• 作者：Sebastian Seiffert ; Wilhelm Oppermann
• 关键词：Tracer diffusion ; FRAP ; Semidilute solutions and networks
• 刊名：Polymer
• 出版年：2008
• 出版时间：9 September 2008
• 年：2008
• 卷：49
• 期：19
• 页码：4115-4126
• 全文大小：1135 K

文摘

The dynamics of fluorescently labeled linear macromolecules and spherical particles that are enclosed in semidilute polymer matrixes was studied by fluorescence recovery after photobleaching. The experiments were designed such that the transition from a semidilute solution to a permanent network could be covered. This was achieved by employing a matrix polymer, polyacrylamide, carrying pendant dimethylmaleimide groups. Stepwise irradiation of such samples in the presence of a triplet sensitizer causes successive dimerization of the maleimides leading to progressive crosslinking.

Studies were performed with varying concentrations of matrix polymer (20–80 g L⁻¹) as well as different molar masses (200,000–1,300,000 g mol⁻¹) and particle radii (17 and 36 nm) of enclosed labeled probes. Results show notable differences between the behavior of linear and spherical tracers: while the mobility of flexible linear chains remains nearly unaffected by the transition from a semidilute polymer solution into a chemically crosslinked network, spherical tracers get completely immobilized when the degree of crosslinking exceeds a certain threshold.