About

Ralph H. Colby received his B.S. in Materials Science and Engineering from Cornell University in 1979. After working for two years at the General Electric Company in rheology research and process development, he attended Northwestern University, where he earned his M.S. and Ph.D. in Chemical Engineering in 1983 and 1985, respectively. His graduate research focused on the rheology of linear polybutadiene melts and solutions, including a 15-month period as a visiting scholar at Exxon Research and Engineering Company. He then worked for ten years at the Eastman Kodak Company's Corporate Research Laboratories, conducting rheology research on linear polymer melts and solutions, miscible polymer blends, block copolymers, randomly branched polymers, polymer gels, liquid crystalline polymers, polyelectrolytes, proteins, surfactants, and colloidal suspensions. In 1995, Dr. Colby joined Pennsylvania State University as an Associate Professor of Materials Science and Engineering and was promoted to Professor in 2000. He teaches undergraduate courses on Polymer Processing and graduate courses on Polymer Physics. Dr. Colby has authored over 130 publications and published a textbook titled 'Polymer Physics' in 2003. His research group focuses on understanding the dynamics of interesting liquids at a molecular level, particularly viscoelastic polymer liquids, liquid crystals, and surfactants, using mechanical rheology, dielectric spectroscopy, neutron and x-ray scattering, and optical methods. His work aims to elucidate structure-property relations in the liquid state, with technological impacts in polymer processing, ionomer membranes, and materials for actuators, sensors, and batteries. Dr. Colby has received numerous awards, including the Penn State Faculty Scholar Medals for Outstanding Achievement in 2022, the Bingham Medal from the Society of Rheology in 2012, and an American Chemical Society Fellowship.

Research topics

• Chemistry
• Materials science
• Polymer chemistry
• Composite material
• Quantum mechanics
• Physical chemistry
• Chemical engineering
• Chemical physics
• Organic chemistry
• Physics
• Thermodynamics

Selected publications

• Formation of Anisotropic Flow-Induced Morphologies above the Equilibrium Melting Temperature in Isotactic Polypropylene

  Macromolecules · 2026-04-27

  articleOpen accessSenior authorCorresponding

  Shearing an isotactic polypropylene melt, even above its equilibrium melting temperature (Tm° ∼ 187 °C) leads to the formation of stable flow-induced precursors. Anisotropic structures result from shearing at temperatures as high as 220 °C (>30 °C above Tm°), and are no longer generated at shearing temperatures exceeding 230 °C. The long periods increase with deformation, accompanied by a change in structural morphology. The crystallization kinetics were strongly affected by flow at shearing temperatures near Tm° and persist at even higher shearing temperatures, as chains continue to be aligned and stretched with large deformations, perhaps further stabilized by stretched chains adsorbing onto heterogeneous impurities from polymerization.

  PublisherDOI

• Giant energy storage and dielectric performance in all-polymer nanocomposites

  Nature · 2026-02-18 · 2 citations

  article
  PublisherDOI

• A Solid State Zwitterionic Plastic Crystal With High Static Dielectric Constant

  Advanced Materials · 2026-01-16

  articleOpen accessSenior authorCorresponding

  ABSTRACT Solid materials with a high dielectric constant have a wide range of applications in the energy storage field. In this research, an imidazolium‐based zwitterion is designed, synthesized, and confirmed to have a plastic crystal phase based on the following experimental and computational evidence: (i) the presence of long‐range order with weak intermolecular forces and competing attractive‐repulsive interactions along different crystallographic directions; (ii) the observation of more than one endotherm on heating including a solid‐solid phase transition at T s‐s = −26 °C and melting of the plastic crystal at T m = 72°C; (iii) a low entropy of fusion at melting (2.1 JK −1 mol −1 ); (iv) a strongly anisotropic morphology; (v) relatively fast dynamics originating from short‐range degrees of freedom. Furthermore, it exhibits a very high dielectric constant in the plastic crystal solid state (147 at −10°C and 103 at 70°C) due to the rotational degrees of freedom of plastic crystals that arise from weak net intermolecular interactions of zwitterions due to only having two carbons between the anion and cation. This material conveniently remains in the plastic crystal phase within 50 K of ambient temperature. This discovery opens new opportunities in the search for solid‐state high dielectric constant materials.

  PublisherOA PDFDOI

• A Solid State Zwitterionic Plastic Crystal with High Static Dielectric Constant

  Zenodo (CERN European Organization for Nuclear Research) · 2025-08-18

  datasetOpen accessSenior author

  The dielectric data in Figure 3, Figure 4, Figure S6 of the published paper was extracted from 2EOIMTSA-BDS-DATA .txt file. This file can be directly opened using a text file editor. It can also be imported to Excel/ Origin for further plotting and analysis. The G' and G'' in Figure 3 of the publihsed paper was plotted from data in file 2EOImTSA-temperature-sweep.xlsx. This file can be directly opend using Excel. The details of DFT simulations mentioned in Figure 2, Figure 7, and Figure S9 of the published paper are included in the DFT.zip file.

  PublisherDOI

• Isothermal crystallization of Poly(ether ether ketone)/carbon fiber composites

  Composites Part B Engineering · 2025-03-08 · 10 citations

  article
  PublisherDOI

• Co‐continuous composites from cold sintering

  Journal of the American Ceramic Society · 2025-06-03 · 4 citations

  article

  Abstract Cold sintering enables the fabrication of ceramic matrix‐polymer composites through low temperature densification by employing a transient solvent under moderate pressure to drive diffusional processes. This innovative processing allows the integration of seemingly incompatible components in a single step to provide new possibilities for tailored multifunctional composites. However, the microstructure of these cold‐sintered composites is controlled by a complex interplay between solubility, evaporation, plastic flow and compaction of the inorganic particles. Pressure solution creep process densifies the inorganic particulates through the dissolution, transport and precipitation at the interfaces of the particulates under applied stresses and slightly elevated temperatures. Through selection of ceramic (gypsum and MgO) and polymer (polypropylene and polymethyl methacrylate) materials that differ in densification mechanisms, new insights are gleaned about how material selection impacts the morphology and mechanical behavior of cold‐sintered composites. Cold sintering of gypsum leads to a well‐densified ceramic, while rapid hydration of MgO leads to minimal densification of the inorganic phase. This difference in ceramic densification affected characteristics of the composites, including the polymer distribution, phase connectivity, and mechanical performance. The high compaction of gypsum during cold sintering facilitated polymer infiltration between particles to form co‐continuous phases on cold sintering. In contrast, the limited densification of MgO did not promote flow of polymer and produced isolated polymer domains that led to poor mechanical performance in the cold sintered composites. Although the cold sintering temperature impacts the rheology of the polymer phase to alter the infiltration of the plastic between the inorganic phase during processing, the primary factor dictating the formation of co‐continuous phases and corresponding good mechanical performance is signficant densification of the ceramic during cold sintering. The processing temperature and material interactions between the polymer and inorganic phases also impact the morphology of cold sintered ceramic‐polymer composites. The combination of materials selection and cold sintering processing parameters provide routes to control morphology for engineering composites with cold sintering with a key heuristic identified here that the inclusion of the polymer cannot overcome poor sintering of the ceramic and densification (compaction) during cold sintering appears to drive the flow and developed connectivity of the polymer phase.

  PublisherDOI

• Boosting Discharge Energy Density of Commercially Available Polyethylene via Post-Polymerization Modification

  Macromolecules · 2025-12-01

  article

  Enhancing polymer dielectric properties is critical for more efficient and reliable energy storage, sensors, and actuators. However, achieving high dielectric constant and low dielectric loss tangent in polymer materials is challenging without incurring higher cost in comparison to polyolefins that are widely used as dielectric materials. Here, we demonstrate postpolymerization modification (PPM) of linear low-density polyethylene (LLDPE) by using azide–alkyne click chemistry to covalently attach polar amines and zwitterions to the backbone, dramatically improving dielectric performance. Amine- and zwitterion-functionalized LLDPE exhibited greater dielectric constants (εs = 12 and 5.6, respectively) than unfunctionalized LLDPE (εs = 2.8). Moreover, the trade-off in functionalizing LLDPE was minimal with the dielectric loss tangent (tan δ) increasing from 0.0002 to 0.007–0.17 at 1 kHz and 30 °C and a modest reduction in the breakdown strength. Electric displacement–electric field loop studies indicate that the discharge energy density (Ud) of amine-modified LLDPE (Ud = 1.59 J/cm3 at 150 MV/m with a high efficiency of 83.5%) outperforms that of poly(vinylidene fluoride), a high-performance ferroelectric polymer, and is 7 times greater than that of the pristine LLDPE. PPM provides a versatile approach to enhance the dielectric properties of commercially available polyolefins for capacitor applications through covalent attachment of polar functionality.

  PublisherDOI

• Crystallization of Polyamide 66 in Blends with a Random Noncrystallizable Poly(hexamethylene isophthalamide-<i>co</i>-terephthalamide)

  Macromolecules · 2025-07-30 · 2 citations

  article

  Many polymers exhibit bimodal temperature-dependent crystallization kinetics, with two distinct crystallization time minima at low and high temperatures. These regimes are typically governed by different nucleation mechanisms and are often associated with formation of different crystal polymorphs. In this work, we identify a strategy to systematically modulate the crystallization kinetics of polyamide 66 (PA 66) across both regimes by incorporating a random noncrystallizable poly(hexamethylene isophthalamide-co-terephthalamide) (PA 6I/6T). The addition of PA 6I/6T systematically slows down crystallization of PA 66, and an apparent transition from a bimodal to unimodal crystallization kinetics is observed when the PA 6I/6T content exceeds 30 wt %. Although this change of the kinetics suggests α-phase dominance, fast scanning calorimetry (FSC), combined with other analytical techniques, collectively provide undisputable evidence that the persistence of mesophase formation at low temperature is not governed by overall crystallization kinetics. Instead, our results indicate that the selection between mesophase and α-phase is dictated by a fundamental, temperature-dependent switch in nucleation mechanism from heterogeneous to homogeneous nucleation. This finding rules out purely kinetic control as the primary cause of polymorph selection under deep undercooling conditions. Thermal analysis also shows a single glass transition temperature (Tg) across all blends, in both amorphous and semicrystalline states, confirming molecular-level miscibility between PA 66 and PA 6I/6T. The upward shift in Tg after crystallization indicates enrichment of PA 6I/6T in the amorphous matrix, consistent with selective exclusion during PA 66 crystallization. The mechanisms governing the slowing down of the crystallization process are extensively discussed. Together, these findings provide fundamental insights into how an amorphous component affects the crystallization kinetics, polymorphic selection, and phase behavior in polymer blends across a wide crystallization temperature range.

  PublisherDOI

• Shear‐Induced Nematic Alignment in Polysulfone Melts

  Advanced Functional Materials · 2025-06-01 · 1 citations

  articleOpen accessSenior authorCorresponding

  Abstract Polymer melt processing often requires conditions of temperature and shear that create flow‐induced structures that impact the properties of the resulting material. Such an effect is connected to chain stretching, often leading to shear‐induced nematic alignment of at least the longest chains, reported for rod‐like polymers but also polyolefins. A polysulfone melt is shown here to undergo such nematic alignment, as can be predicted from its chain stiffness. Its convenient chain linearity, verified by very good agreement of the linear viscoelastic data with a tube model (BoB) for entangled polymer melts, and its inability to crystallize make it suitable for exploring the temperature dependence of the nematic alignment, monitored by both rheology and birefringence. The critical shear rate for nematic alignment at various temperatures is determined and contrasted with that expected from the Rouse time of the longest chains, often considered as the control parameter. Although the onset shear rate for nematic alignment is shown to follow the same temperature dependence as the chain relaxation times, suggesting that chain stretching is the underlying mechanism, the critical shear rate is much smaller than expected. This anomalous behavior of polysulfone is discussed in relation with possible π‐stacking interactions stabilizing the nematic domains.

  PublisherOA PDFDOI

• Polyzwitterionic Material Structure and Dielectric Properties

  Langmuir · 2025-04-07 · 3 citations

  article

  There is a growing need for flexible, high-dielectric-constant materials that move beyond current polar solvent swelling and nanofiller approaches to advance energy storage and actuator applications. Here, we synthesized a series of statistical copolymers consisting of polybutyl acrylate-co-poly(2-(dimethylamino)ethyl acrylate), which were then converted into polyzwitterions to explore the impact of zwitterions on the material structure and dielectric properties. The DMAEA residues in each copolymer were quaternized using 1,4-butane sultone to yield polyzwitterions through postpolymerization modification. The functionalization of the copolymers with zwitterions increases the static dielectric constant of the materials (i.e., ∼9.3 at 80 °C) compared with the unquaternized materials. The strong dipolar interactions between zwitterions lead to aggregation, resulting in the appearance of either a second glass-transition temperature or the softening of the zwitterion aggregates. Although the zwitterions increased the dielectric constant of the materials, the zwitterion-rich aggregates are posited to restrict zwitterion mobility, precluding the maximum material dielectric constant. The reported findings position polyzwitterions as promising next-generation dielectric materials, potentially broadening applications in flexible electronics and energy-efficient devices.

  PublisherDOI

Recent grants

• First Principles Design of Ionomers for Facile Ion Transport

  NSF · $313k · 2009–2013

• Collaborative: Viscoelasticity of Nanoparticle Dispersed Polymer Melts: Experiment and Simulation

  NSF · $553k · 2010–2016

• Energy materials based on single-ion conducting polymers mixed with zwitterions

  NSF · $634k · 2018–2023

• Controlling Rheology by Tuning Colloidal Interactions

  NSF · $296k · 2010–2014

• SusChEM: Rheology of Cellulose and other Biopolymers in Ionic Liquids

  NSF · $345k · 2015–2020

Frequent coauthors

• Gary L. Leal

  University of California, Santa Barbara

  469 shared

• A. Jeffrey Giacomin

  University of Nevada, Reno

  468 shared

• Albert Co

  323 shared

• Albert Co

  152 shared

• Sanat K. Kumar

  Columbia University

  50 shared

• James Runt

  Pennsylvania State University

  45 shared

• Quan Chen

  Huaiyin Institute of Technology

  44 shared

• U Hyeok Choi

  42 shared

Labs

• Ralph Colby LabPI

Awards & honors

• Penn State Faculty Scholar Medals for Outstanding Achievemen…
• Bingham Medal, Society of Rheology (2012)
• American Chemical Society Fellowship