Influence of Architecture on the Interaction of Negatively Charged Multisensitive Poly(N-isopropylacrylamide)-co-Methacrylic Acid Microgels with Oppositely Charged Polyelectrolyte: Absorption vs Adsorption
Influence of Architecture on the Interaction of Negatively Charged Multisensitive Poly(N-isopropylacrylamide)-co-Methacrylic Acid Microgels with Oppositely Charged Polyelectrolyte: Absorption vs Adsorption
复制标题
DOI：
10.1021/la100579b
复制
发表时间：
2010-07-06
期刊：
影响因子：
3.9
通讯作者：
Richtering, Walter
中科院分区：
文献类型：
--
作者：
Kleinen, Jochen;Klee, Andreas;Richtering, Walter
制备了两组由温度敏感型聚n -异丙基丙烯酰胺（PNiPAM）组成的核壳微凝胶，其ph敏感型甲基丙烯酸（maa）基团的空间分布不同。磁芯由PNiPAM（中性磁芯；tic）或PNiPAM-co- maa（带电磁芯；cc）组成。在中性核上加入已有的PNiPAM-co-MAA带电壳层（产生中性核带电壳；nccs）；另一方面，加入PNiPAM的中性壳层（带电核中性壳；混合）。制备了带正电的不同摩尔质量的聚二烯基二甲基氯化铵（PDADMAC）微凝胶配合物。对结合的聚电解质的数量进行了量化，并对微凝胶-聚电解质复合物的电泳迁移率和流体动力半径进行了表征。通过对一种与聚l -赖氨酸共价结合的荧光染料的寿命分析来监测聚电解质对微凝胶的渗透，从而提供有关探针局部环境的信息。微凝胶的结构对其与带相反电荷的聚电解质的相互作用有显著的影响。带电荷壳的微凝胶配合物在电荷比为I时倾向于絮凝，因此类似于具有刚性胶体颗粒的聚电解质配合物。由带电核和中性壳组成的微凝胶复合物表现出非常不同的性质：它们仍然对温度敏感，并显示出聚电解质链长度的一部分。低分子量PDADMAC可以穿透中性壳层进入带电核，因此几乎不发生电荷反转。高毫瓦的聚电解质不能完全穿透，导致电荷反转。结果表明，微凝胶吸附聚电解质的能力取决于聚电解质的链长和微凝胶的结构。可以制备具有不同表面性质和不同胶体稳定性的配合物，并将聚电解质封装在微凝胶芯中。因此，多敏感核壳微凝胶在纳米尺度上结合了渗透性和区隔性，为控制吸收和释放提供了独特的应用机会。
Two sets of core-shell microgels composed of temperature-sensitive poly(N-isopropylacrylamide) (PNiPAM) with different spatial distribution of pH-sensitive methacrylic acid (M AA) groups were prepared. The cores consist or either PNiPAM (neutral core; tic) or PNiPAM-co-MAA (charged core; cc). A charged shell existing of PNiPAM-co-MAA was added to the neutral core (yielding neutral core charged shell; nccs), on the charged core; on the other hand, a neutral shell of PNiPAM was added (charged core neutral shell; mix). Complexes of these microgels with positively charged poly(diallyldimethylammonium chloride) (PDADMAC) of different molar masses were prepared. The amount of bound polyelectrolyte was quantified, and the microgel-polyelectrolyte complexes were characterized with respect to electrophoretic mobility and hydrodynamic radius. The penetration of polyelectrolyte into the microgel was also monitored by means of lifetime analysis of a fluorescent dye covalently bound to poly(L-lysine) providing information on the probe's local environment. The architecture or the microgel has a significant influence on the interaction with oppositely charged polyelectrolyte. Complexes with microgel with the charged shell tend to flocculate at charge ratios of I and are thus similar to polyelectrolyte complexes with rigid colloidal particles. Complexes with microgels that consist of a charged core and a neutral shell show very different properties: They are still temperature sensitive and reveal an in of the polyelectrolyte's chain length. Low molecular weight PDADMAC can penetrate through the neutral shell into the charged core, and thus nearly no charge reversal occurs. The high-MW polyelectrolyte does not penetrate fully and leads to charge reversal. The results demonstrate that microgels are able to absorb or adsorb polyelectrolytes depending on the polyelectrolyte's chain length and the microgels architecture. Complexes with different surface properties and different colloidal stability can be prepared, and polyelectrolytes can be encapsulated in the microgel core. Thus, multisensitive core shell microgels combine permeability and compartmentalization on a nanometer length scale and provide unique opportunities for applications in controlled uptake and release.