A novel in situ intercalative polymerization technique was used to disperse clay mineral in a precursor resin for use in UV curing by performing an in situ ion exchange reaction during polyesterification. Unmodified montmorillonite (MMT) was added to a reaction mixture composed of monomers and methyl, tallow, bis-2-hydroxyethyl ammonium (MTEtOH) during the synthesis of unsaturated polyesters to create resins containing highly dispersed, organically modified MMT. UV-curable clay–polymer nanocomposite (CPN) films were then prepared utilizing donor–acceptor chemistry through reactions of the unsaturated polyester resin with triethylene glycol divinyl ether. Functional group conversion improved up to 15% by the incorporation of clay mineral into the polymer matrix through the in situ polymerization method. The CPNs also had improved barrier, mechanical, and thermal properties over a control film containing no clay mineral. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42601.

Renewable polymeric materials derived from biomass with built-in phototriggers were synthesized and evaluated for degradation under irradiation of UV light. Complete decomposition of the polymeric materials was observed with recovery of the monomer that was used to resynthesize the polymers.

A new 100 % bio-based thermosetting coating system was developed from epoxidized sucrose soyate crosslinked with blocked bio-based dicarboxylic acids. A solvent-free, green method was used to block the carboxylic acid groups and render the acids miscible with the epoxy resin. The thermal reversibility of this blocking allowed for the formulation of epoxy-acid thermoset coatings that are 100 % bio-based. This was possible due to the volatility of the vinyl ethers under curing conditions. These systems have good adhesion to metal substrates and perform well under chemical and physical stress. Additionally, the hardness of the coating system is dependent on the chain length of the diacid used, making it tunable.

The potential of nanoclay organic modifiers to induce plasticizing effects in resin and coatings systems was studied. In previous work, it was found that while low amounts of incorporation of organomodified clays significantly improved the physical and mechanical properties of a ultraviolet (UV)-curable nanocomposite, further increasing the organomodified clay content could result in the reduction of properties. To investigate the potential impact of the organic modifier composition and concentration on polymer properties, a series of experiments were carried out using only the organic modifier. Methyl, tallow, bis-2-hydroxyethyl ammonium (MTEtOH), the organic modifier used in montmorillonite clay Cloisite® 30B, was dispersed with precursor polyester oligomers at 1–10 wt % through an in situ synthesis process and via sonication, and UV-curable coatings were prepared from these MTEtOH-containing resins. The organic modifier cetyltrimethylammonium bromide (CTAB) was also studied to examine the impact of the organic modifier structure. According to differential scanning calorimetry, small decreases in the glass transition temperatures (T_g) of the MTEtOH-containing polyesters were observed, but CTAB-containing polyesters had small T_g increases. Polyester molecular weight and viscosity were also affected by both the structure of the organic modifier as well as its concentration. The mechanical performance of the UV-curable coatings diminished with increased MTEtOH concentration for the films containing the organic modifier compared to a control film. Furthermore, the crosslink density was found to reduce ∼ 50% with increased MTEtOH loading into the UV-curable films. The cure characteristics, thermal stability, and optical clarity were also studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Ultraviolet-curable nanocomposites containing organically modified nanoclays were prepared to serve as barrier coatings against oxygen and water permeation. A novel in situ synthesis technique was used to produce well-dispersed clays in an unsaturated polyester polymer before crosslinking. The in situ dispersion route was compared with nanocomposites prepared by mixing and sonication for several levels of nanoclay loading (1, 2, 5, and 10 wt %). The comparison of nanocomposite properties prepared from each processing method demonstrated that the in situ preparation technique led to better clay dispersion as verified by transmission electron microscopy. The in situ route for nanoclay dispersion produced nanocomposites with lower water vapor transmission and permeability compared with the sonicated dispersion method. The impact on cure characteristics, mechanical properties, thermal stability, and optical clarity of the nanocomposites were also compared. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

High-functionality polyols for application in polyurethanes (PUs) were prepared by epoxide ring-opening reactions from epoxidized sucrose esters of soybean oil—epoxidized sucrose soyates—in which secondary hydroxyl groups were generated from epoxides on fatty acid chains. Ester polyols were prepared by using a base-catalyzed acid–epoxy reaction with carboxylic acids (e.g., acetic acid); ether polyols were prepared by using an acid-catalyzed alcohol–epoxy reaction with monoalcohols (e.g., methanol). The polyols were characterized by using gel permeation chromatography, FTIR spectroscopy, ¹H NMR spectroscopy, differential scanning calorimetry (DSC), and viscosity measurements. PU thermosets were prepared by using aliphatic polyisocyanates based on isophorone diisocyanate and hexamethylene diisocyanate. The properties of the PUs were studied by performing tensile testing, dynamic mechanical analysis, DSC, and thermogravimetric analysis. The properties of PU coatings on steel substrates were evaluated by using ASTM methods to determine coating hardness, adhesion, solvent resistance, and ductility. Compared to a soy triglyceride polyol, sucrose soyate polyols provide greater hardness and range of cross-link density to PU thermosets because of the unique structure of these macromolecules: well-defined compact structures with a rigid sucrose core coupled with high hydroxyl group functionality.

Industrial grade soybean oil (SBO) and thiols were reacted to generate thiol-functionalized oligomers via a thermal, free radical initiated thiol–ene reaction between the SBO double bond moieties and the thiol functional groups. The effect of the reaction conditions, including thiol concentration, catalyst loading level, reaction time, and atmosphere, on the molecular weight and the conversion to the resultant soy–thiols were examined in a combinatorial high-throughput fashion using parallel synthesis, combinatorial FTIR, and rapid gel permeation chromatography (GPC). High thiol functionality and concentration, high thermal free radical catalyst concentration, long reaction time, and the use of a nitrogen reaction atmosphere were found to favor fast consumption of the SBO, and produced high molecular weight products. The thiol conversion during the reaction was inversely affected by a high thiol concentration, but was favored by a long reaction time and an air reaction atmosphere. These experimental observations were explained by the initial low affinity of the SBO and thiol, and the improved affinity between the generated soy–thiol oligomers and unreacted SBO during the reaction. The synthesized soy–thiol oligomers can be used for renewable thiol–ene UV curable materials and high molecular solids and thiourethane thermal cure materials.

A humidity blocker approach to overcoming the humidity interference with cationic photopolymerization is proposed and validated. Environmental humidity is one of the major interfering factors in cationic photopolymerization, and cationic photopolymerization is found to be inhibited by high humidity. When curing cycloaliphatic epoxide based cationic UV curable materials flexibilized by various reactive diluents under different humidity conditions, it was found that the more hydrophobic materials exhibited higher monomer conversion under higher humidity. To obtain cationic UV curable materials that are less influenced by humidity, a humidity blocker approach was proposed and monomer conversion of materials containing both hydroxy-functional reactive diluents and epoxy-siloxane were examined using real-time FTIR. The hydroxy-functional reactive diluents act as an internal hydroxyl source that enhances monomer conversion through chain transfer mechanism, and the hydrophobic epoxy-siloxane acts as a humidity blocker, mitigating the inhibiting effects of humidity. Cationic UV curable materials with an optimized combination of these two components exhibited higher and more consistent monomer conversion under a range humidity conditions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4344–4351, 2008