About

Peter Beltramo is an Associate Professor in the Chemical and Biomolecular Engineering Department at UMass Amherst, affiliated with the Riccio College of Engineering. His research group focuses on applying fundamental engineering principles and novel techniques to understand and engineer interfacial processes, which are prevalent across various applications. His work encompasses creating biomimetic materials for drug delivery, stabilizing emulsions in the food and petroleum industries, and exploring biophysical phenomena such as information transfer through cell membranes and particle/membrane interactions. Beltramo's research employs well-defined model experiments to replicate the essential physics of complex interfacial problems, gradually increasing in complexity through a bottom-up approach. His interdisciplinary research overlaps with fields including chemical engineering, physics, biology, and materials science, aiming to manipulate particle size, shape, and surface chemistry to develop super-stable emulsions and novel photonic materials.

Research topics

• Materials science
• Composite material
• Nanotechnology
• Chemical engineering
• Physics
• Mechanics
• Geometry
• Optics
• Organic chemistry
• Mathematics
• Polymer chemistry
• Chemical physics
• Chromatography
• Biophysics
• Chemistry
• Biochemistry

Selected publications

• Ordered interfacial assembly of rough microellipsoids

  ChemRxiv · 2026-05-22

  articleOpen accessSenior author

  Dense, orientationally and translationally ordered, two-dimensional (2D) monolayers of colloidal ellipsoids are fabricated at air-water interfaces. Kinetic arrest and disordered structures from long-range quadrupolar capillary attraction are overcome by synthesizing polystyrene microellipsoids with surface roughness, specifically nanoscale concavities, which attenuate capillary attraction. With increasing area fraction, the particle assembly shows a disorder-order transition from isotropic to plastic crystal at low ellipsoid aspect ratio (AR) and an isotropic to nematic transition at high AR, agreeing qualitatively with simulated hard ellipse close-packing in 2D. The ordered particle assembly is successfully transferred to solid substrates via Langmuir-Blodgett deposition, demonstrating the potential of surface roughness to create anisotropically ordered 2D patterns via interfacial templating.

  PublisherDOI

• Engineering active colloidal dynamics at a lipid bilayer interface

  Soft Matter · 2026-01-01

  articleOpen accessSenior authorCorresponding

  concentration increases the particles become increasingly wrapped in the membrane, as evidenced by their altered translational and rotational dynamics. We apply active Brownian models to characterize the nature of the particle-membrane interactions and also particle pair interactions. These results lay the groundwork to combine active colloidal systems with model lipid membranes to understand active transport in cellular contexts.

  PublisherOA PDFDOI

• Controlling self-assembly and interfacial mechanics of polymer spheres and ellipsoids at fluid interfaces with surface roughness

  ChemRxiv · 2025-09-12

  articleSenior author

  In this study, we describe the effect of surface topography on monolayer assembly and mechanics of spherical and ellipsoidal colloids at an air-water interface. Building off our prior work which directly measured the roughness-dependent capillary pinning of individual particles, we now show how the reduction in capillary interaction energy between rough ellipsoids, and increase in interaction energy between spheres, impacts their collective assembly. Two types of surface topography (convex/concave) and two degrees of roughness are compared with their smooth analogues. With increasing roughness, the measured surface pressure increases for spheres, in accordance with stronger capillary interactions, and decreases in ellipsoids, likewise confirming that individual particle attributes impacts their monolayer properties. However, the type of surface topography, not just the roughness magnitude, is shown to be a critical aspect of the assembly morphology as the interfaces approach their jammed state. In particular, concave rough ellipsoids are observed to form a complete unidirectional monolayer with high area fraction (~0.86), avoiding the kinetically arrested assemblies and low area fraction jamming (0.68) shown by smooth ellipsoids. Moreover, monolayers of concave rough ellipsoids demonstrate a two-dimensional interfacial isotropic–nematic phase transition with increasing particle areal density. The surface topography mediated capillary pinning and wetting behavior, coupled with the altered interparticle interactions and resultant interfacial microstruture further dictates the monolayer’s ability to resist compressive deformation and collapse mechanics. These findings open up opportunities to realize complex 2D ordered microstructures from anisotropic particles and manipulate fluid-fluid interface stability in emulsions and foams by leveraging particle topography and shape engineering.

  PublisherDOI

• Controlling self-assembly and interfacial mechanics of polymer spheres and ellipsoids at fluid interfaces with surface roughness

  Soft Matter · 2025-11-18

  articleSenior author

  In this study, we describe the effect of surface topography on monolayer assembly and mechanics of spherical and ellipsoidal colloids at an air-water interface. Building off our prior work which directly measured the roughness-dependent capillary pinning of individual particles, we now show how the reduction in capillary interaction energy between rough ellipsoids, and the increase in interaction energy between spheres, impacts their collective assembly. Two types of surface topography (convex/concave) and two degrees of roughness are compared with their smooth analogues. With increasing roughness, the measured surface pressure increases for spheres, in accordance with stronger capillary interactions, and decreases in ellipsoids, confirming that individual particle attributes impact their monolayer properties. However, the type of surface topography, not just the roughness magnitude, is shown to be a critical aspect of the assembly morphology as the interfaces approach their jammed state. In particular, concave rough ellipsoids are observed to form a complete unidirectional monolayer with high area fraction (∼0.86), avoiding the kinetically arrested assemblies and low area fraction jamming (0.68) shown by smooth ellipsoids. Moreover, monolayers of concave rough ellipsoids demonstrate a two-dimensional interfacial isotropic-nematic phase transition with increasing particle areal density. The surface topography mediated capillary pinning and wetting behavior, coupled with the altered interparticle interactions and the resultant interfacial microstructure, further dictates the monolayer's ability to resist compressive deformation and collapse mechanics. These findings open up opportunities to realize complex two-dimensional (2D) ordered microstructures from anisotropic particles and manipulate fluid-fluid interface stability in emulsions and foams by leveraging particle topography and shape engineering.

  PublisherDOI

• Engineered Active Colloids Drive Environmental and Biomimetic Technologies

  ACS Applied Engineering Materials · 2025-10-24

  article1st authorCorresponding
  PublisherDOI

• Encapsulation of Inorganic Nanoparticles by Anionic Emulsion Polymerization of Diethyl Methylene Malonate for Developing Hybrid Microparticles with Tailorable Composition

  Colloids and Interfaces · 2024-02-02 · 3 citations

  articleOpen accessSenior authorCorresponding

  Colloidal particle self-assembly into higher-ordered structures has been of great interest due to the promise of creating metamaterials with novel macroscopic properties. The physicochemical properties of these metamaterials can be tailored to achieve composites with tunable functionalities, either by controlling the assembly morphology and/or chemistry of the colloidal building blocks. This work describes a strategy of developing microparticles with a hybrid configuration that have an inorganic and an organic part. The inorganic part comprises functional nanoparticles, which are embedded within an organic polymer particle composed of diethyl methylene malonate polymer [p(DEMM)] prepared using anionic emulsion polymerization. DEMM polymerization is initiated entirely by the presence of hydroxyl anions and the resulting particle diameter can be tuned between 300 nm and 1 micrometer by reaction pH. Inorganic nanoparticles with varying chemistry (TiO2, CdTe, ZnO) can be loaded into the p(DEMM) particle with a controlled weight fraction, as confirmed by thermogravimetric analysis. The colloidal stability of the composite microparticles is seen to be dependent on the ligand coating attached to the inorganic constituent. These results provide a synthetic groundwork for creating hybrid, stimuli-responsive microparticles.

  PublisherOA PDFDOI

• The paradoxical behavior of rough colloids at fluid interfaces

  ChemRxiv · 2024-04-25

  preprintOpen accessSenior author

  Colloidal particles adsorb and remain trapped at immiscible fluid interfaces due to strong interfacial adsorption energy, with a contact angle defined by the chemistry of the particle and fluid phases. An undulated contact line may appear due to either particle surface roughness or shape anisotropy, which results in a quadrupolar interfacial deformation and strong long range capillary interaction between neighboring particles. While each effect has been observed separately, here we report the paradoxical impact of surface roughness on spherical and anisotropic ellipsoidal polymer colloids. Using a seeded emulsion polymerization technique, we synthesize spherical and ellipsoidal particles with controlled roughness magnitude and topography (concave/convex). Via in situ measurement of the interfacial deformation around colloids at an air-water interface, we find that while surface roughness strengthens the quadrupolar deformation in spheres as expected by theory, in stark contrast, it weakens the same in ellipsoids. As roughness increases, particles of both shapes become more hydrophilic and their apparent contact angle decreases. Using numerical predictions, we show that this partially explains the decreased interfacial deformation and capillary interactions between ellipsoids. Therefore, particle surface engineering has the potential to decrease the capillary deformation by asymmetric particles via changing their capillary pinning as well as wetting behavior at fluid interfaces.

  PublisherOA PDFDOI

• The Paradoxical Behavior of Rough Colloids at Fluid Interfaces

  ACS Applied Materials & Interfaces · 2024-06-26 · 8 citations

  articleSenior authorCorresponding

  Colloidal particles adsorb and remain trapped at immiscible fluid interfaces due to strong interfacial adsorption energy with a contact angle defined by the chemistry of the particle and fluid phases. An undulated contact line may appear due to either particle surface roughness or shape anisotropy, which results in a quadrupolar interfacial deformation and strong long-range capillary interaction between neighboring particles. While each effect has been observed separately, here we report the paradoxical impact of surface roughness on spherical and anisotropic ellipsoidal polymer colloids. Using a seeded emulsion polymerization technique, we synthesize spherical and ellipsoidal particles with controlled roughness magnitudes and topography (convex/concave). Via in situ measurement of the interfacial deformation around colloids at an air-water interface, we find that while surface roughness strengthens the quadrupolar deformation in spheres as expected by theory, in stark contrast, it weakens the same in ellipsoids. As roughness increases, particles of both shapes become more hydrophilic, and their apparent contact angle decreases. Using numerical predictions, we show that this partially explains the decreased interfacial deformation and capillary interactions between the ellipsoids. Therefore, particle surface engineering has the potential to decrease the capillary deformation by asymmetric particles via changing their capillary pinning, as well as wetting behavior at fluid interfaces.

  PublisherDOI

• The paradoxical behavior of rough colloids at fluid interfaces

  ChemRxiv · 2024-06-17 · 1 citations

  preprintOpen accessSenior author

  Colloidal particles adsorb and remain trapped at immiscible fluid interfaces due to strong interfacial adsorption energy, with a contact angle defined by the chemistry of the particle and fluid phases. An undulated contact line may appear due to either particle surface roughness or shape anisotropy, which results in a quadrupolar interfacial deformation and strong long range capillary interaction between neighboring particles. While each effect has been observed separately, here we report the paradoxical impact of surface roughness on spherical and anisotropic ellipsoidal polymer colloids. Using a seeded emulsion polymerization technique, we synthesize spherical and ellipsoidal particles with controlled roughness magnitude and topography (concave/convex). Via in situ measurement of the interfacial deformation around colloids at an air-water interface, we find that while surface roughness strengthens the quadrupolar deformation in spheres as expected by theory, in stark contrast, it weakens the same in ellipsoids. As roughness increases, particles of both shapes become more hydrophilic and their apparent contact angle decreases. Using numerical predictions, we show that this partially explains the decreased interfacial deformation and capillary interactions between ellipsoids. Therefore, particle surface engineering has the potential to decrease the capillary deformation by asymmetric particles via changing their capillary pinning as well as wetting behavior at fluid interfaces.

  PublisherOA PDFDOI

• Effects of Ion Concentration and Headgroup Chemistry on Thin Lipid Film Drainage

  Langmuir · 2023-11-08 · 1 citations

  articleSenior authorCorresponding

  While the use of lipid nanoparticles in drug delivery applications has grown over the past few decades, much work remains to be done toward the characterization and rational design of the drug carriers. A key feature of delivery is the interaction of the exterior leaflet of the LNP with the outer leaflet of the cell membrane, which relies in part on the fusogenicity of the lipids and the ionic environment. In this paper, we study the interactions between two lipid monolayers using a thin film balance to create lipid thin films and interferometry to measure film evolution. We probe the role of lipid headgroup chemistry and charge, along with ionic solution conditions, in either promoting or hindering film drainage and stability. Specific headgroups phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylserine (PS) are chosen to represent a combination of charge and fusogenicity. We quantify each film’s drainage characteristics over a range of capillary numbers. Qualitatively, we find that films transition from drainage via a large dimple to drainage via channels and vortices as the capillary number increases. Additionally, we observe a transition from electrostatically dominated film drainage at low CaCl2 concentrations to fusogenic-dominated film drainage at higher CaCl2 concentrations for anionic fusogenic (PS) films. Understanding the role of headgroup composition, ionic composition, and ionic concentration will pave the way for the design of tunable vesicle and buffer systems that behave desirably across a range of ex vivo and in vivo environments.

  PublisherDOI

Recent grants

• Cloaking Anisotropic Capillary Interactions Through Tunable Nanoscale Surface Topography

  NSF · $382k · 2023–2027

• CAREER: Understanding the interplay between lipid composition and biomolecule transport in biological membranes

  NSF · $592k · 2020–2027

Frequent coauthors

• Eric M. Furst

  University of Delaware

  10 shared

• Oscar Zabala-Ferrera

  University of Massachusetts Amherst

  10 shared

• Paige Liu

  University of Massachusetts Amherst

  10 shared

• Jan Vermant

  ETH Zurich

  9 shared

• Samuel Trevenen

  University of Massachusetts Amherst

  7 shared

• Md Anisur Rahman

  University of Massachusetts Amherst

  6 shared

• George Fytas

  6 shared

• D. Schneider

  4 shared

Education

• PhD, Department of Chemical and Biomolecular Engineering

  University of Delaware

  2014

Awards & honors

• Lilly Teaching Fellow (2020-2021)
• NSF CAREER Award (2020)
• ACS-PRF DNI Award (2019)
• Student Centered Teaching and Learning Fellow (2018–2019)