Professional Education


  • Doctor of Philosophy, University of California Santa Barbara (2021)
  • Bachelor of Science, North Carolina State Univ At Raleigh (2015)

Stanford Advisors


All Publications


  • Flow-Induced Concentration Nonuniformity and Shear Banding in Entangled Polymer Solutions PHYSICAL REVIEW LETTERS Burroughs, M. C., Zhang, Y., Shetty, A. M., Bates, C. M., Leal, L., Helgeson, M. E. 2021; 126 (20): 207801

    Abstract

    Recent models have predicted entangled polymer solutions could shear band due to unstable flow-induced demixing. This work provides the first experimental probe of the in situ concentration profile of entangled polymer solutions under shear. At shear rates above a critical value, we show that the concentration and velocity profiles can develop bands, in quantitative agreement with steady-state model predictions. These findings highlight the critical importance of flow-concentration coupling in entangled polymer solutions.

    View details for DOI 10.1103/PhysRevLett.126.207801

    View details for Web of Science ID 000652840600012

    View details for PubMedID 34110187

  • Cellulose nanocrystals for gelation and percolation-induced reinforcement of a photocurable poly(vinyl alcohol) derivative SOFT MATTER Corder, R. D., Adhikari, P., Burroughs, M. C., Rojas, O. J., Khan, S. A. 2020; 16 (37): 8602-8611

    Abstract

    Nanomaterials are regularly added to crosslinkable polymers to enhance mechanical properties; however, important effects related to gelation behavior and crosslinking kinetics are often overlooked. In this study, we combine cellulose nanocrystals (CNCs) with a photoactive poly(vinyl alcohol) derivative, PVA-SbQ, to form photocrosslinked nanocomposite hydrogels. We investigate the rheology of PVA-SbQ with and without CNCs to decipher the role of each component in final property development and identify a critical CNC concentration (1.5 wt%) above which several changes in rheological behavior are observed. Neat PVA-SbQ solutions exhibit Newtonian flow behavior across all concentrations, while CNC dispersions are shear-thinning <6 wt% and gel at high concentrations. Combining semi-dilute entangled PVA-SbQ (6 wt%) with >1.5 wt% CNCs forms a percolated microstructure. In situ photocrosslinking experiments reveal how CNCs affect both the gelation kinetics and storage modulus (G') of the resulting hydrogels. The modulus crossover time increases after addition of up to 1.5 wt% CNCs, while no modulus crossover is observed >1.5 wt% CNCs. A sharp increase in G' is observed >1.5 wt% CNCs for fully-crosslinked networks due to favorable PVA-SbQ/CNC interactions. A percolation model is fitted to the G' data to confirm that mechanical percolation is maintained after photocrosslinking. A ∼120% increase in G' for 2.5 wt% CNCs (relative to neat PVA-SbQ) confirms that CNCs provide a reinforcing effect through the percolated microstructure formed from PVA-SbQ/CNC interactions. The results are testament to the ability of CNCs to significantly alter the storage moduli of crosslinked polymer gels at low loading fractions through percolation-induced reinforcement.

    View details for DOI 10.1039/d0sm01376e

    View details for Web of Science ID 000573714400003

    View details for PubMedID 32845269

  • Coupled nonhomogeneous flows and flow-enhanced concentration fluctuations during startup shear of entangled polymer solutions PHYSICAL REVIEW FLUIDS Burroughs, M. C., Shetty, A. M., Leal, L., Helgeson, M. E. 2020; 5 (4)
  • Distinguishing shear banding from shear thinning in flows with a shear stress gradient RHEOLOGICA ACTA Cheng, P., Burroughs, M. C., Leal, L., Helgeson, M. E. 2017; 56 (12): 1007-1032
  • Cooperative Assembly of Metal Nitrate and Citric Acid with Block Copolymers: Role of Carbonate Conversion Temperature on the Mesostructure of Ordered Porous Oxides JOURNAL OF PHYSICAL CHEMISTRY C Burroughs, M. C., Bhaway, S. M., Tangvijitsakul, P., Cavicchi, K. A., Soucek, M. D., Vogt, B. D. 2015; 119 (22): 12138-12148
  • Cyclodextrin facilitated electrospun chitosan nanofibers RSC ADVANCES Burns, N. A., Burroughs, M. C., Gracz, H., Pritchard, C. Q., Brozena, A. H., Willoughby, J., Khan, S. A. 2015; 5 (10): 7131-7137

    View details for DOI 10.1039/c4ra09662b

    View details for Web of Science ID 000347609400015