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Dispersion at Single Unit TiO2 Nanoparticles Reduced Tg, Induced Chain Disentanglement and Reduced Tensile Modulus in Waterborne Acrylic Coatings
Macromolecular Materials and Engineering ( IF 4.2 ) Pub Date : 2020-12-28 , DOI: 10.1002/mame.202000591
Angel Romo‐Uribe 1
Affiliation  

Spatially distributed TiO2 nanoparticles induced an order of magnitude decrease of glass transition temperature, Tg, and chain disentanglement in waterborne acrylic coatings. Acrylic/TiO2 coatings are synthesized in situ by batch emulsion polymerization. The copolymer is based on butyl acrylate (BA), methyl methacrylate (MMA), and acrylic acid (AA) with composition 56:42:2 mol%, and nano‐TiO2 (ca. 12 nm) is incorporated up to 3 wt% content. Transmission electron microscopy (TEM) showed that TiO2 is dispersed at nearly single unit throughout the acrylic matrix. The nanoparticle reduced Tg and broadened the temperature range of the glass transition, δTg. The considerable increase of δTg suggests gradients of dynamics. Shear rheometry demonstrated that TiO2 induced chain disentanglement, the rubbery modulus Ge decreased two orders of magnitude with only 1 wt% TiO2 content thus increasing the packing length p (and the reptation tube diameter as dt = kp, k > 1). Consequently, the tensile Young's modulus E decreased an order of magnitude, relative to the neat copolymer. The reduction of Tg, the slowdown of macromolecular dynamics, the chain disentanglement and the increase of dt suggests dynamics modification due to intercalation of the entangled web by the TiO2 nanoparticles, and these results may be ascribed to a nanoconfinement effect.

中文翻译:

TiO2纳米粒子在单单元中的分散性降低了水性丙烯酸涂料的Tg,诱导的链解缠和降低的拉伸模量

空间分布的TiO 2纳米颗粒导致水性丙烯酸涂料的玻璃化转变温度T g和链解缠度降低了一个数量级。通过间歇乳液聚合原位合成丙烯酸/ TiO 2涂层。该共聚物基于丙烯酸丁酯(BA),甲基丙烯酸甲酯(MMA)和丙烯酸(AA)组成,组成为56:42:2 mol%,并掺入了高达3 wt %的nano-TiO 2(约12 nm) % 内容。透射电子显微镜(TEM)表明,TiO 2以几乎单一的单元分散在整个丙烯酸基质中。纳米颗粒降低了T g并扩大了玻璃化转变的温度范围,δT。的相当大的增加δT表明动力学的梯度。剪切流变法表明,TiO 2引起链解缠,橡胶模量G e仅以TiO 2含量为1 wt%降低了两个数量级,从而增加了填料长度p(并且延长管直径为d t = kp,k  > 1) 。因此,相对于纯共聚物,拉伸杨氏模量E降低了一个数量级。T g降低,大分子动力学减慢,链解缠和d t增大提示由于TiO 2纳米颗粒对缠结的网状材料的嵌入而引起的动力学改变,并且这些结果可能归因于纳米约束作用。
更新日期:2021-02-15
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