Morphology Evolution of Polystyrene-core/Poly(N-isopropylacrylamide)-shell Microgel Synthesized by One-pot Emulsion Polymerization
writer：Wen-tao Hua, Hua Yangb, He Chengb, and Hai-qing Hu
keywords：sans
source：期刊
specific source：journal of chinese polymer science
Issue time：2017年
One-pot emulsion polymerization with macroinitiator is supposed to be a robust, facile
way to synthesize well-defined core-shell nanoparticles with fixed shell thickness. To testify this, we calibrated the temperature dependence morphology evolution of polystyrene (PS) core/poly(N-isopropylacrylamide) (PNIPAM) shell microgel synthesized by one-pot emulsion polymerization with PNIPAM-RAFT as macroinitiator in dimethylformamide (DMF) by combined transmission electron microscopy (TEM), dynamic/static light scattering (DLS/SLS) and small angle neutron scattering (SANS). It is revealed that the microgel has a core-shell structure, i.e., the core is made of pure PS, but the shell is composed of both PNIPAM-RAFT macroinitiator and crosslinked PS. In fact, there are 92.0 wt% D2O,
6.7 wt% PNIPAM and 1.3 wt% PS in the shell in its aqueous solution at 21 °C; therefore, its shell thickness is much larger than the extended chain length of the macroinitiator in both SANS and DLS observation. Competitive growth of styrene, divinylbenzene and PNIPAM macroinitiator as well as possible chain transfer from amine proton of PNIPAM side chain may lead to the non-ideal shell thickness, which is not equal to the extended chain length of the macroinitiator. Our work may shed light on the real morphology control in
one-pot emulsion polymerization.
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:普通表格;
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-parent:"";
mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
mso-para-margin:0cm;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:10.0pt;
font-family:"Times New Roman",serif;}