Joaquin Stella
Advisor: Prof. Brettmann

will defend a master's thesis entitled,

Aluminum Isopropoxide: A Versatile Crosslinker for the Development of Organic-Inorganic Hybrid Materials 

On

Tuesday, April 21 at 3:00 p.m.
EBB Conference Room 5029

and/or

 Virtually via MS Teams or Zoom

https://teams.microsoft.com/l/meetup-join/19%3ameeting_ZWI4NmZhNjItN2YxYi00N2UwLWJhMjYtNDM4NGRiMDRhMDg4%40thread.v2/0?context=%7b%22Tid%22%3a%22482198bb-ae7b-4b25-8b7a-6d7f32faa083%22%2c%22Oid%22%3a%22d94c616a-028c-45a9-9c4a-6d0ca86cc35e%22%7d

Committee
            Prof. Blair Brettmann – School of Materials Science and Engineering, School of Chemical and Biomolecular Engineering (Advisor)
            Prof. Lukas Graber – School of Electrical and Computer Engineering
            Prof. Juan-Pablo Correa-Baena – School of Materials Science and Engineering

Abstract

Organic-inorganic (OI) hybrid materials are a class of materials combining organic and inorganic components at the molecular level, creating a synergistic effect in properties that is greater than the sum of each part. Epoxy resins are known for having high chemical and corrosion resistance, high impact resistance, toughness, and outstanding adhesion. They are widely used as adhesives, high-performance composite matrices for aerospace and sporting goods, and protective coatings against corrosive and radiative environments. By incorporating inorganic materials into the epoxy matrix at the molecular level, properties of the organic epoxy and the inorganic fillers can be covalently connected, decreasing the risks of phase separation and leading to a homogenous hybrid material. Existing epoxy OI hybrid materials typically rely on silicon as the inorganic component and require the addition of hardeners, catalysts, or solvents to generate a crosslink network. Aluminum isopropoxide (AIP) presents an opportunity for the development of a two-part epoxy – AIP hybrid system. AIP takes on a dual-functional role as both an initiator for the ring-opening polymerization (ROP) of the epoxide ring and as an inorganic crosslinking center.

In this work, I demonstrate that AIP concentration influences the thermal properties of the epoxy – AIP network and can match or exceed that of epoxy resins cured with traditional hardeners. Curing was carried out under high pressure (300 psi) to suppress bubbling from the volatilization of free isopropanol generated during the reaction, enabling the formation of consistent, defect-free hybrid materials.

This work analyzes and compares the results of three epoxy systems: a commercial epoxy resin (EC 1159A), 2,2-Bis(4-glycidyloxyphenyl)propane / Bisphenol A diglycidyl ether (DGEBA), and Bis(7-oxabicyclo[4.1.0]heptan-3-ylmethyl) adipate  (BECHMA). Thermal properties of the commercial epoxy – AIP, DGEBA – AIP, and BECHMA – AIP systems cured at varying AIP concentrations revealed the effects AIP has on the crosslinking network and the thermal stability of the systems. At 15 wt% AIP, a more homogenous crosslinked network formed, evidenced by the higher reported values for glass transition and onset of thermal degradation, while increased AIP concentrations resulted in hybrids with a greater resistance to total thermal degradation and higher thermal stability.

Overall, this work highlights the strong initiation properties of AIP towards the ROP reaction of epoxide rings. Combined with its tri-functional nature, AIP is a powerful cross-linker that is applicable across the investigated systems and can be used to cure epoxy resins with relative simplicity, resulting in consistent effects on the thermal properties.