Pompe Tilo, Renner Lars, Grimmer Milauscha, Herold Nicole, Werner Carsten
Leibniz Institute of Polymer Research Dresden, Max Bergmann Center of Biomaterials Dresden, Hohe Str. 6, 01069 Dresden, Germany.
Macromol Biosci. 2005 Sep 16;5(9):890-5. doi: 10.1002/mabi.200500097.
Reactivity and swelling of nanometer films of alternating maleic anhydride copolymers were investigated in dependence on the kind of comonomer and molar mass of copolymer in aqueous solution at pH 7.4 and pH 3.0 in order to reveal their characteristics under physiological conditions. Fully hydrolyzed (maleic acid) chains of the copolymers with styrene, propene, and ethylene comonomers covalently bound to SiO2 substrates showed a "mushroom" swelling behavior at pH 7.4 with a layer thickness scaling of N3/5. Decreasing the environmental pH was found to induce a comonomer-dependent shrinking or collapse of the immobilized polymers due to the change in ionization. From the swelling kinetics of non-hydrolyzed chains, the time constants and characteristics of swelling and anhydride hydrolysis were determined and found to depend on the type of comonomer. The short- and long-term swelling kinetics [l approximately t and approximately ln(t)1/2] were found to be in agreement with theoretical models of polymer swelling, while at intermediate time scales enhanced swelling was observed due to hydrolysis reaction of maleic anhydride groups. The findings elucidate the variety of properties of maleic anhydride copolymer films under physiological conditions, which can advantageously be applied for biofunctionalization of different templates.
为了揭示交替型马来酸酐共聚物纳米薄膜在生理条件下的特性，研究了其在pH值为7.4和pH值为3.0的水溶液中，根据共聚单体种类和共聚物摩尔质量所表现出的反应活性和溶胀情况。与苯乙烯、丙烯和乙烯共聚单体形成的共聚物中完全水解的（马来酸）链共价结合在SiO₂ 基底上，在pH值为7.4时呈现出“蘑菇状”溶胀行为，层厚度标度为N³/⁵。研究发现，由于电离变化，降低环境pH值会导致固定化聚合物出现共聚单体依赖性的收缩或塌陷。根据未水解链的溶胀动力学，测定了溶胀和酸酐水解的时间常数及特性，发现其取决于共聚单体的类型。短时间和长时间的溶胀动力学 [l约为t，约为ln(t)¹/²] 与聚合物溶胀的理论模型一致，而在中间时间尺度上，由于马来酸酐基团的水解反应，观察到溶胀增强。这些发现阐明了马来酸酐共聚物薄膜在生理条件下的多种特性，可有利地应用于不同模板的生物功能化。
