Morphology Control And Self-assembly Of The Red Blood Cell-like Colloidal Particles

With the anisotropy in structure,the red blood cell-like(RBC-like)colloidal particles exhibit the excellent physical and chemical properties and show great applicable value in the fields of the optical materials,the functional coating,the electric and the medicine.At present,the precise morphology control and the repeatability still have been the challenges during preparation of RBC-like colloidal particles and the application research of RBC-like colloidal particles is still in the initial stage.In this thesis,we succeeded in controlling the morphology of RBC-like colloidal particles precisely and exploring the formation mechanism.In addition,we also investigated the self-assembly behavior of RBC-like colloidal particles at air-water interface and driven by depletion force.(1)The RBC-like colloidal particles were synthesized via one-pot dispersion polymerization.The precise control of morphology was realized by adjusting divinylbenzene(DVB)concentration,the start feeding time of DVB,the total feeding time of DVB,the St mass ratio in stage I and stage II,and the mass ratio of ethanol and water in solvent.When the DVB concentration was between 0.5 wt% and 5.0 wt%,the start feeding time of DVB was between 1.5 h and 4.5 h,and the DVB feeding time was no less than 3.0 h,the RBC-like colloidal particles with smooth or multi-dimple surface were synthesized.The RBC-like colloidal particles could be obtained by regulating the mass ratio of St monomer from 10:10 to 19:1.In addition,no less than 9:1 of the mass ratio between ethanol and water provided a favorable condition for the generation of RBC-like colloidal particles.The main formation mechanism of RBC-like colloidal particles was attributed to the phase separation between cross-linked network and St homopolymer interior of the junior nuclei induced by the uneven distribution of cross-linked network.Because of the incompatibility between St homopolymer and cross-linked network,St homopolymer was forced to move to those zones where cross-linked density was relatively small,resulting in the formation of RBC-like colloidal particles.(2)The RBC-like colloidal particles were driven by the capillary attraction and convective force to assemble into the single-layer colloidal crystal at air-water interface.The self-assembly of RBC-like colloidal particles was controlled by adjusting mass ratio of ethanol and deionized water,particles concentration and SDS concentration.When the mass ratio of ethanol and deionized water was 3:2,the particles concentration was between 4.41×10-5 g?cm-2 and 6.29×10-5 g?cm-2,the SDS concentration was between 1.99×10-5 g?mL-1 and 4.95×10-5 g?m L-1,the high quality single-layer colloidal crystal was obtained.(3)The assembly of RBC-like colloidal particles and spherical PS particles was investigated by addition a non-adsorbing water-soluble polymer PEO to the system,where PEO was used as depletant.We investigated the effect of PEO concentration and the size of PS particles on the assembly.When the dimension of PS particles was greater than or equal to the size of the concave on the RBC-like colloidal particles and the PEO concentration was 1.2g/L,the RBC-like particles and PS particles were able to assemble together effectively.The principle behind depletion interaction was the entropy maximization: depletant was added to the solution,and maximum system entropy was achieved when the depletant had maximum freedom of motion.