Polymers, Colloids, and Materials Science
The research activity of the group is focused on the study of the phase behavior, assembled nanostructures, governing interactions and functional properties of biopolymers, synthetic polymers and special amphiphiles in aqueous and complex media. The research provides a broad training of both synthesis and physicochemical characterization of polymers, complexes, and hydrogels from nano- to micro- length scale. Specific projects of research include:
Intelligent polymer materials
Environmentally sensitive polymers/hydrogels have continuously attracted interests due to their enormous potential in various applications, such as drug delivery, chemical separations, sensors, and biomaterials. However, development of sensitive hydrogels with rapid response, better biocompatibility and controllable degradability is a formidable challenge. The objective of this project is to develop rapid responsive microgels with a wide array of desirable properties based on polysaccharides and polypeptides. Fundamentally, we investigate the effects of the composite compositions and environmental conditions (e.g., temperature, pH, and ions) on the nanostructures, phase transitions, and degradation behaviour of the microgels.
Polymeric nanoparticles from assembly
While polymeric particles are promising to overcome drug delivery challenges such as site-targeting and delivery options, the control of the particulate characteristics such as degradability, biocompatibility, size, surface properties, inner structures, and hydrophobicity are crucial for manipulating the loading and diffusion properties of therapeutic molecules as well as the transportation of the carrier particles through biological membrane. To tailor these specific properties of polymeric nanoparticles, we do chemical modification of polysaccharide chains with special chain architecture design. We study the influence of the structural graft chain composition and architecture on the macromolecular self-assembly and complexation to find out the defined tailoring of these polymeric nanoparticles. The functions for controlled release of model proteins will be connected with the degradation and structural properties of these nanoparticles.
Nanostructures of novel surfactants and their hybrid phases
The control of morphologies and nanostructures of supramolecular surfactant assembly is of utmost importance in both fundamental understanding of interface science and technological applications. While microemulsions and highly ordered nanostructures from surfactant assembly have been used to tailor the size, morphology and structures of various inorganic, polymeric and biological nanomaterials, we are fabricating 2D and 3D nanostructures of Fullerene ball based on self-assembly strategy. We are also investigating the morphological and nanostructural transition of surfactant hybrid phases, particularly focusing on the novel type of polymer-modified degradable surfactants. Fundamentally, we seek to understand the equilibrium between micelles, vesicles, oligomers, and liquid crystals via hybridizing surfactants with specially designed chemical structure. Technologically, we are trying to connect the morphologies and structures of the hybrid surfactant phases to the stability, rheology, shear sensitivity, and controlled release behavior of the concentrated dispersions and gels.
Polyelectrolyte-surfactant complexes
Polyelectrolytes have important biological and materials applications, e.g. as stabilizer, gelling agents, super-absorbants, flocculants, coatings or polyelectrolyte complex membranes for special separation processes or microencapsulation. In collaboration with the Dow Chemical Company, our interest is mainly focused on the complex systems formed by cationic polysaccharides with anionic/amphoteric surfactants. The main objective is to fundamentally understand the mechanism and the chemical and physical factors influencing the flocculation and stabilization of dispersions and the delivery of functional actives in personal care products, such as anti-dandruff and UV-block ingredients. We investigate the phase behavior, assembled structure, size/size distribution, and rheology of the polycations-surfactant complexes. To discover the general effects, we monitor a number of key factors, like concentration and mixing ratio of polycations and surfactants, charge density and location of the polycations, chain flexibility, hydrophobicity and architectures of polycations.
The individual project neither requires nor is isolated from others. We provide sufficient capacity for diverse individual style and progress in performing researches while the active interactions among the members are maximized.
Our major fundamental techniques include static and dynamic laser light scattering, rheometric spectrometer, and synchrotron X-ray scattering (NSLS at Brookhaven National Laboratory). We will also take advantage of the resources available in our Department, including NMR, spectrophotometers, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM).
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