Sütekin S Duygu, Kiraç Feyza, Güven Olgun
Department of Chemistry, Faculty of Science, Hacettepe University, Ankara, Turkey.
Turk J Chem. 2023 Feb 1;47(2):386-398. doi: 10.55730/1300-0527.3545. eCollection 2023.
An easy method is proposed to prepare poly(vinyl pyrrolidone) (PVP) and poly(N-isopropylacrylamide) (PNiPAAm) nanogels with sizes less than 100 nm. The underlying principle is to prepare dilute polymer solutions in acetone/water mixtures where acetone acts to break tridimensional structure of water hence disrupting the H-bonds bridging polymer coils causing separation and shrinkage in their sizes. Irradiation of these solutions by gamma-rays directly leads to the formation of intramolecular crosslinks within the coils resulting with nanogels with sizes smaller than precursor coils. While the average size of nanogels of PVP irradiated in water only is 236 nm, they were reduced to about 44 nm when irradiation was carried out in acetone/water solutions at near theta compositions. PNiPAAm nanogels were also synthesized by irradiating their dilute acetone/water solutions. Multimodal coil size distribution of PNiPAAm was converted into monomodal distribution with 70 nm average size and low dispersity by the addition of acetone. Irradiation of such solutions yielded PNiPAAm nanogels with 50 nm average size. Stability of nanogels was followed for 1 year not showing any changes in their sizes or size distributions. Nanogels were characterized by dynamic light scattering, scanning electron microscopy, and atomic force microscopy techniques.
提出了一种制备尺寸小于100 nm的聚（乙烯基吡咯烷酮）（PVP）和聚（N-异丙基丙烯酰胺）（PNiPAAm）纳米凝胶的简便方法。其基本原理是在丙酮/水混合物中制备稀聚合物溶液，其中丙酮起到破坏水的三维结构的作用，从而破坏连接聚合物线圈的氢键，导致其尺寸分离和收缩。用γ射线辐照这些溶液直接导致线圈内分子内交联的形成，从而产生尺寸小于前体线圈的纳米凝胶。仅在水中辐照的PVP纳米凝胶的平均尺寸为236 nm，而在接近θ组成的丙酮/水溶液中进行辐照时，其尺寸减小到约44 nm。PNiPAAm纳米凝胶也通过辐照其稀丙酮/水溶液合成。通过加入丙酮，PNiPAAm的多峰线圈尺寸分布转变为平均尺寸为70 nm且分散度低的单峰分布。辐照此类溶液得到平均尺寸为50 nm的PNiPAAm纳米凝胶。对纳米凝胶的稳定性跟踪了1年，其尺寸或尺寸分布未显示任何变化。通过动态光散射、扫描电子显微镜和原子力显微镜技术对纳米凝胶进行了表征。
