I obtained my PhD in Polymer Physical Chemistry from Georgia Tech under the direction of Professor L. Andrew Lyon. I have also received my Master's degree in Polymer Chemistry from the University of Toronto and Peking University. My bachelor's degree was in Polymer Materials from Sichuan University. In my research, I combine theoretical calculations with experimental synthesis.
I have been working on hydrogel, including macrogel and microgel, for 9 years. My research interests range from thermoreversible biodegradable hydrogels, silicone-based hydrogels, to thermosensitive microgels. All these hydrogels and microgels are based upon water soluble thermoresponsive polymer, poly(N-isopropyacrylamide) (pNIPAm). The structure of pNIPAm is shown below.
While the temperature is below the lower critical solution temperature (LCST) of pNIPAm, the polymer is water soluble with a coil configuration; whereas when the temperature is above the LCST of pNIPAm, the polymer collapses to globule. Corresponding to coil-to-globule transition is the linear pNIPAm, cross-linked pNIPAm networks demonstrate a volume phase transition at the LCST, also called volume phase transition temperature (VPTT).
Exploring the structure-property correlation of hydrogels and their applications in a variety of fields, such as drug delivery, water purification, and sensors, are very important. I have been working on the aging and phase behavior of pNIPAm-Acrylic Acid (AAc) random copolymeric microgel particles in closed systems. The aging of pNIPAm-AAc microgel dispersions is associated with slower microscopic dynamics and swollen particle volumes, which is shown below. In the concentrated regime, aging is associated with phase transition from a fluid state to a crystalline state.
Furthermore, the inter-particle attractive interactions evolve during aging, probably due to the rearrangement of dangling chains of pNIPAm-AAc microgels to minimize local free energy, which is demonstrated by the enhanced thermostability of colloidal crystals. Finally, similar to hard sphere dispersions, microgel dispersions show a gas-liquid-crystal-glass transition series by increasing their volume fractions.
Microgels are not only a great model for fundamental physics, but also a great candidate for drug delivery vehicles and sensors. Functionalization of microgels with bioorthogonal click chemistry is a feasible approach to simultaneously modify microgels with a variety of functional groups without side reactions. Cu(I)-catalyzed azide-terminal alkyne 1,3-dipolar cycloaddtion is one of the most important reactions in click chemistry tool box, which is used for the simultaneous functionalization of microgels with both carboxylic acid and azide groups.
I married my wife, Qing Ye, in December, 2001, and we had our daughter in March, 2008. My hobbies include surfing the internet (chat or watch news), jogging, and GO chess.
Published Papers and Book Chapters:
[1] Physical Aging and Phase Behavior of Multi-Responsive Microgel Colloidal Dispersions. Meng, Zhiyong; Cho, Jae Kyu; Breedveld, Victor; Lyon, L. Andrew. Journal of Physical Chemistry B (2009), 113, 4590-4599
[2] Thermoresponsive microgel-based materials Lyon, L. Andrew; Meng, Zhiyong; Singh, Neetu; Sorrell, Courtney; St. John, Ashlee. Chemical Society Reviews (2009), 38, 865-874
[3] Temperature-Programmed Synthesis of Micron-Sized Microgels. Meng, Zhiyong; Lyon, L. Andrew, Colloid and Polymer Science (2009), 287, 277-285
[4] Crystallization Behavior of Soft, Attractive Microgels. Meng, Zhiyong; Cho, Jae Kyu; Debord, Stella; Breedveld, Victor; Lyon, L. Andrew. Journal of Physical Chemistry B (2007), 111, 6992-6997.
[5] Tunable attractive and repulsive interactions between pH-responsive microgels. Cho, Jae Kyu; Meng, Zhiyong, Lyon, L. Andrew, Breedveld Victor. Soft Matter (2009) doi: 10.1039/b912105f
[6] Microgels for Sensors, Microlenses, and Photonic Crystals Lyon, L. Andrew; Grant, Hendrickson; Meng, Zhiyong; St. John, Ashlee. Invited book chapter submitted for Wiley-VCH publishing book
[7] Multi-responsive clickable microgels Meng, Zhiyong; Lyon, L. Andrew Macromolecules doi: 10.1021/ma9013719
[8] Interaction of sulfonated polystyrene with cationic surfactants in aqueous solution. Meng, Zhiyong; Lu, Yingxian; Cao, Weixiao. Journal of Macromolecular Science, Pure and Applied Chemistry (2001), A38, 233-242
[9] Interaction of sodium dodecyl sulfate with polyelectrolyte complexes derived from diazo resin and sulfonate-containing polymers. Cao, Weixiao; Meng, Zhiyong; Tao, Yie; Zhang, Donghui; Yang, Boxuan. Journal of Polymer Science, Part A: Polymer Chemistry (1999), 37, 2601-2606.
Manuscripts In Preparation:
[1] Multi-functional membrane composed of clickable microgels Meng, Zhiyong; Lyon, L. Andrew in preparation for Advanced Materials
[2] Ultrathin films composed of cross-linker free microgels Meng, Zhiyong; South, Toni B.; Yen, Howard; Lyon, L. Andrew in preparation for Angewandt Chemie-International Edition
[3] Phase Behavior of Colloidal Dispersions - Interaction Potential Meng, Zhiyong; Lyon, L. Andrew in preparation for Accounts of Chemical Research
