About

Stephen A. Miller is a Professor and Associate Chair in the Department of Chemistry at the University of Florida. His main research focus is on the synthesis of sustainable polymers derived from biorenewable feedstocks, with the goal of mimicking commodity thermoplastics. These polymers are generally designed to be biodegradable or water-degradable. His work includes the use of computational methods to understand unusual polymerization and depolymerization chemistry, such as hydrolysis under environmentally relevant conditions. Additionally, Miller is developing Long Covalent Bond Theory (LCBT), a theoretical framework that significantly expands the understanding of bonding in molecules and materials. His educational background includes a B.S. and M.S. in Chemistry from Stanford University, a Ph.D. in Chemistry from the California Institute of Technology, and a postdoctoral fellowship at the Massachusetts Institute of Technology in Richard R. Schrock's lab. His contributions to the field include advancing knowledge in sustainable polymer chemistry and bonding theories, with publications addressing water-degradable materials and the structure of silica through the application of LCBT.

Research topics

• Computer Science
• Materials science
• Chemistry
• Nanotechnology
• Engineering
• Optoelectronics
• Polymer chemistry
• Polymer science
• Organic chemistry
• Chemical engineering
• Electrical engineering

Selected publications

• Bio-oil derived polyesteramides as water-degradable replacements for polyethylene

  Green Chemistry · 2025-01-01 · 12 citations

  articleOpen accessSenior authorCorresponding

  Polyesteramides derived from Ethiopian mustard seed bio-oil possess commercially relevant thermomechanical properties and are chemically recyclable and water-degradable.

  PublisherOA PDFDOI

• Entropy-Driven Depolymerization of Poly(dimethylsiloxane)

  Macromolecules · 2023-05-12 · 11 citations

  articleSenior authorCorresponding

  Poly(dimethylsiloxanes) (PDMSs) are widely used because of their unique properties but require a highly polluting and energy-intensive synthesis starting from silica. Chemical recycling offers an opportunity to regenerate new materials with comparable properties while avoiding the inefficiencies of the de novo synthesis. Herein, we report computational and experimental results of depolymerizing PDMS with diols. Computationally, depolymerization with methanol is always endergonic, while depolymerization with 2-methyl-2,4-pentanediol (hexylene glycol, HG) is exergonic over a wide temperature range. Acid-catalyzed exchange reactions between SiMe2(OMe)2 and hexylene glycol show silicon’s thermodynamic preference for the diol due to entropically favorable chelation. An optimized procedure for depolymerizing PDMS with hexylene glycol to a cyclic monomer, M2HG, was developed and applied to a variety of commercial PDMS sources. Cyclic siloxanes are byproducts early in the reaction, requiring a two-step process to obtain highly pure M2HG. The procedure is selective for PDMS even in complex reaction mixtures and gives good yields (38–78%) regardless of the starting material used. Polymerizing M2HG back to PDMS proved challenging but feasible. Ring-opening polymerization of M2HG was catalyzed by trifluoromethanesulfonic acid or p-toluenesulfonic acid to yield low-molecular-weight polysilicon acetals (Mn up to 1500) or high-molecular-weight PDMS (Mn ∼ 39,900), respectively. Terpolymerizations of M2HG with vinyl ethers and aldehydes also yielded low-molecular-weight material (Mn up to 5000). PDMS was successfully reconstituted from M2HG under cationic emulsion polymerization conditions, affording high molecular weights up to Mn = 49,000.

  PublisherDOI

• The location of the chemical bond. Application of long covalent bond theory to the structure of silica

  Frontiers in Chemistry · 2023-02-16 · 10 citations

  articleOpen access1st authorCorresponding

  Oxygen is the most abundant terrestrial element and is found in a variety of materials, but still wanting is a universal theory for the stability and structural organization it confers. Herein, a computational molecular orbital analysis elucidates the structure, stability, and cooperative bonding of α-quartz silica (SiO 2 ). Despite geminal oxygen-oxygen distances of 2.61–2.64 Å, silica model complexes exhibit anomalously large O-O bond orders (Mulliken, Wiberg, Mayer) that increase with increasing cluster size—as the silicon-oxygen bond orders decrease. The average O-O bond order in bulk silica computes to 0.47 while that for Si-O computes to 0.64. Thereby, for each silicate tetrahedron, the six O-O bonds employ 52% (5.61 electrons) of the valence electrons, while the four Si-O bonds employ 48% (5.12 electrons), rendering the O-O bond the most abundant bond in the Earth’s crust. The isodesmic deconstruction of silica clusters reveals cooperative O-O bonding with an O-O bond dissociation energy of 4.4 kcal/mol. These unorthodox, long covalent bonds are rationalized by an excess of O 2 p –O 2 p bonding versus anti-bonding interactions within the valence molecular orbitals of the SiO 4 unit (48 vs. 24) and the Si 6 O 6 ring (90 vs. 18). Within quartz silica, oxygen 2 p orbitals contort and organize to avoid molecular orbital nodes, inducing the chirality of silica and resulting in Möbius aromatic Si 6 O 6 rings, the most prevalent form of aromaticity on Earth. This long covalent bond theory (LCBT) relocates one-third of Earth’s valence electrons and indicates that non-canonical O-O bonds play a subtle, but crucial role in the structure and stability of Earth’s most abundant material.

  PublisherOA PDFDOI

• Renewable and water-degradable polyimide-esters from citric acid

  Green Chemistry · 2023-01-01 · 16 citations

  articleSenior authorCorresponding

  Polyimide-esters derived from sustainable citric acid and glycine exhibit commercially-relevant glass transition temperatures and environmentally-relevant water-degradability.

  PublisherDOI

• Catalyst system for the polymerization of alkenes to polyolefins

  OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2023-01-23

  articleOpen access1st authorCorresponding

  The invention provides metallocene catalyst systems for the controlled polymerization of alkenes to a wide variety of polyolefins and olefin coplymers. Catalyst systems are provided that specifically produce isotactic, syndiotactic and steroblock polyolefins. The type of polymer produced can be controlled by varying the catalyst system, specifically by varying the ligand substituents. Such catalyst systems are particularly useful for the polymerization of polypropylene to give elastomeric polypropylenes. The invention also provides novel elastomeric polypropylene polymers characterized by dyad (m) tacticities of about 55% to about 65%, pentad (mmmm) tacticities of about 25% to about 35%, molecular weights (M.sub.w)in the range of about 50,000 to about 2,000,000, and have mmrm+rrmr peak is less than about 5%.

  PublisherOA PDF

• High-speed, scanned laser structuring of multi-layered eco/bioresorbable materials for advanced electronic systems

  Nature Communications · 2022 · 59 citations

  • Computer Science
  • Materials science
  • Nanotechnology

  Physically transient forms of electronics enable unique classes of technologies, ranging from biomedical implants that disappear through processes of bioresorption after serving a clinical need to internet-of-things devices that harmlessly dissolve into the environment following a relevant period of use. Here, we develop a sustainable manufacturing pathway, based on ultrafast pulsed laser ablation, that can support high-volume, cost-effective manipulation of a diverse collection of organic and inorganic materials, each designed to degrade by hydrolysis or enzymatic activity, into patterned, multi-layered architectures with high resolution and accurate overlay registration. The technology can operate in patterning, thinning and/or cutting modes with (ultra)thin eco/bioresorbable materials of different types of semiconductors, dielectrics, and conductors on flexible substrates. Component-level demonstrations span passive and active devices, including diodes and field-effect transistors. Patterning these devices into interconnected layouts yields functional systems, as illustrated in examples that range from wireless implants as monitors of neural and cardiac activity, to thermal probes of microvascular flow, and multi-electrode arrays for biopotential sensing. These advances create important processing options for eco/bioresorbable materials and associated electronic systems, with immediate applicability across nearly all types of bioelectronic studies.

  PublisherOA PDFDOI

• Reductive Amination of Dialdehyde Cellulose: Access to Renewable Thermoplastics

  Biomacromolecules · 2022-12-21 · 41 citations

  articleOpen access

  of 1.30).

  PublisherDOI

• Sustainable One-Pot Synthesis and Polycondensation of a Levoglucosenone-Derived Cyclic Acetal Diol

  ACS Sustainable Chemistry & Engineering · 2022-07-27 · 19 citations

  articleCorresponding

  The already described one-pot two-step hydration/reduction of levoglucosenone (LGO) into (1R,2S,5R)-6,8-dioxabicyclo[3.2.1]octane-2,4-diol (HO-LGOL) was improved by replacing 50 mol % of Et3N by 5 mol % of K3PO4, a more sustainable base. The sterically hindered diol was then subjected to polycondensations with aliphatic comonomers to prepare new bio-based polyesters that exhibit glass transition (Tg) values between 12 and 54 °C and high thermal stability greater than 200 °C. Two different strategies were implemented to perform the polymerizations: (1) utilization of aliphatic diacyl chlorides, or (2) a method involving aliphatic diethyl esters in the presence of a metal catalyst. These methods were then subjected to life cycle assessment to study their environmental impacts.

  PublisherDOI

• Green synthesis of 2-deoxy-D-ribonolactone from cellulose-derived levoglucosenone (LGO): A promising monomer for novel bio-based polyesters

  European Polymer Journal · 2021-09-01 · 14 citations

  articleCorresponding
  PublisherDOI

• Polyvinyl alcohol modification with sustainable ketones

  Polymer Chemistry · 2021-01-01 · 21 citations

  articleSenior authorCorresponding

  Water-degradable polyvinyl ketals with high glass transition temperatures (78–127 °C) were made via ketalization of polyvinyl alcohol (PVA) with sustainable ketones.

  PublisherDOI

Recent grants

• SusChEM: Building Superior Sustainable Polymers with Bioaromatics

  NSF · $465k · 2016–2021

• CAREER: Catalytic Aldimine Coupling: A Versatile Carbon-Carbon Bond Forming Reaction

  NSF · $437k · 2007–2011

• SusChEM: Polyesters from Sustainable C1 Feedstocks

  NSF · $420k · 2013–2017

• Next Generation Thermoplastics from Biorenewable Carbonyl Compounds

  NSF · $383k · 2009–2013

• CAREER: Catalytic Aldimine Coupling: A Versatile Carbon-Carbon Bond Forming Reaction

  NSF · $500k · 2006–2008

Frequent coauthors

• Florian Diot‐Néant

  Agro-Biotechnologies Industrielles

  20 shared

• Florent Allais

  AgroParisTech

  19 shared

• Khalil A. Abboud

  University of Florida

  18 shared

• Michael R. Wasielewski

  Northwestern University

  15 shared

• Joseph H. Reibenspies

  15 shared

• Hsuan‐Ying Chen

  National Pingtung University of Science and Technology

  14 shared

• Pengxu Qi

  University of Florida

  13 shared

• Ha Thi Nguyen

  Vietnam National University Ho Chi Minh City

  12 shared