GDHPPC Lab, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, 510275, China.
GDHPPC Lab, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, 510275, China; Key Lab for Polymer Composite and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
J Colloid Interface Sci. 2015 Jul 15;450:264-271. doi: 10.1016/j.jcis.2015.03.029. Epub 2015 Mar 19.
Narrowly size distributed spherical, ellipsoid-like and lamellae stacked poly(ε-caprolactone) (PCL) nano-aggregates in aqueous dispersions with a diameter ranging from about (∼) 50 to 330 nm were prepared via nanoprecipitation method in the present study. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to characterize the morphology and size of the PCL nano-aggregates. We investigated the melt behaviors of the original (without any thermal treatment after preparation) PCL nano-aggregates in aqueous dispersions by nano differential scanning calorimetry (nano-DSC). In particular, the condensed state of the original ∼50 nm PCL nanospheres was demonstrated to be amorphous as a result of exhibiting no melting peak in the first nano-DSC heating scan. Furthermore, the rubbery↔flow condensed state transition of the amorphous PCL nanospheres was explored by fluorescence measurements. Moreover, the confined crystallization of the ∼50 nm PCL nanospheres from rubbery state in aqueous dispersions was investigated via isothermal crystallization process. Enormous supercooling was observed during crystallization due to nanoconfinement effect. In addition, when the diameter of the original PCL aggregates was increased to more than 150 nm, PCL is in semi-crystalline state and the crystallinity increases with the diameter.
通过纳米沉淀法，制备了在水中分散的具有 50 至 330nm 直径的窄尺寸分布的球形、椭圆形和层状堆叠的聚己内酯（PCL）纳米聚集体。扫描电子显微镜（SEM）、透射电子显微镜（TEM）和原子力显微镜（AFM）用于表征 PCL 纳米聚集体的形态和尺寸。我们通过纳米差示扫描量热法（nano-DSC）研究了原始（制备后未经任何热处理）PCL 纳米聚集体在水中分散体中的熔融行为。特别是，由于在第一次 nano-DSC 加热扫描中没有观察到熔融峰，因此原始约 50nm PCL 纳米球的凝聚态被证明为无定形。此外，通过荧光测量研究了无定形 PCL 纳米球的橡胶态到流动态的凝聚态转变。此外，通过等温结晶过程研究了约 50nm PCL 纳米球从橡胶态在水中分散体中的受限结晶。由于纳米限制效应，在结晶过程中观察到巨大的过冷。此外，当原始 PCL 聚集体的直径增加到 150nm 以上时，PCL 处于半结晶状态，结晶度随直径的增加而增加。
