Dimethyl Meta-isopropenyl Benzyl Isocyanate Research Articles

Hydrolysis of Dimethyl Meta-Isopropenylbenzyl Isocyanate (TMI) and Colloidal Stability of Latexes During Storage: Effect of pH

The hydrolysis of the isocyanate (NCO) group of dimethyl meta-isopropenylbenzyl isocyanate (TMI) and colloidal stability of terpolymer latexes during storage at different pH were studied. These latexes were prepared at 40°C by batch emulsion polymerizations using vinyl acetate (VAc), butyl acrylate (BA) and TMI as monomers and Aerosol A-103 as surfactant. The TMI content was calculated in the poly(VAc-BA-TMI) latex at the end of the polymerization and also monitored during storage (at room temperature). It was found that the hydrolysis of the NCO group of the TMI and the colloidal stability of the latexes were affected to different extents by the pH value. The feasibility that the other chemical groups formed by hydrolysis of the VAc and BA units in the latexes during storage could promote these phenomena is discussed.

“Clickable” polymers via a combination of RAFT polymerization and isocyanate chemistry

We describe a facile, one-pot, two-step polymerization towards synthesizing block co-polymers bearing reactive isocyanate functional groups. Reversible addition fragmentation chain transfer (RAFT) polymerization is used to mediate the co-polymerization of isocyanate-bearing monomers dimethyl meta-isopropenyl benzyl isocyanate (TMI) and 2-isocyanatoethyl methacrylate (ICEMA) with styrene and methyl methacrylate (MMA), respectively. ICEMA was incorporated into the polymer at a faster rate than TMI and its unhindered isocyanate group was found to be more reactive than the hindered isocyanate group of TMI. Both the TMI/styrene and the MMA/ICEMA systems maintain the reactivity of the isocyanate functionality, which was exploited by attaching representative hydroxyl-bearing small and large molecules as well as solid substrates to the block co-polymers. Thus, we demonstrate the versatility of the block co-polymer system as a basis for forming branched polymers or as grafts for a solid substrate. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

'Pseudo-star' Copolymers Formed by a Combination of RAFT Polymerization and Isocyanate-Coupling

We describe the formation of pseudo-star copolymers via incorporation of an isocyanate-bearing monomer, dimethyl meta-isopropenyl benzyl isocyanate (TMI) into a homopolymer of butyl acrylate (BA) using a one-pot, two-step synthesis. The resultant product maintains the functionality of the isocyanate moiety, which is used to attach poly(ethylene glycol) methyl ether onto the copolymeric chain under benign reaction conditions. The resultant pseudo-star copolymers were isolated and their self-assembly in the presence of water studied.

Crosslinking of isocyanate functional acrylic latex with telechelic polybutadiene. I. Synthesis and characterization

An ambient curable isocyanate functional acrylic latex was synthesized by incorporating dimethyl meta-isopropenyl benzyl isocyanate (TMI®), an isocyanate monomer, into styrene/n-butyl acrylate copolymer. An artificial latex of amino-terminated telechelic polybutadiene was prepared and blended with the acrylic latex as a curing agent. The isocyanate content in the blended latex was determined by titration and FTIR measurements. The latex blend properties, in terms of particle size and latex viscosity, and the latex film properties, in terms of stress-strain behavior and solvent swelling behavior, showed no significant change after 30 days' storage of the latex blend at 50°C. The good storage stability was attributed to the stable nature of the latex blend in which there was little chance for the isocyanate-containing particles to come into contact with the curing agent particles, thus preventing premature contact of the acrylic chains with the telechelic chains. The reactivity of different functional groups in the telechelic polymer was studied; the amino group was found to be the most reactive toward the TMI. In addition, a shorter chain telechelic crosslinker was found to result in a higher degree of crosslinking, but this was more intraparticle than interparticle in nature.

Seeded emulsion terpolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI®) with acrylic monomers

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a novel bifunctional monomer. It has a double bond and an isocyanate group. The seeded emulsion terpolymerization of TMI with the acrylic monomers, methyl methacrylate and n-butyl acrylate, has been studied. A copolymer of methyl methacrylate and n-butyl acrylate was used as the seed latex. In order to minimize the risk of hydrolysis of TMI, polymerizations were carried out at 40°C using redox initiators. No additional surfactant was added during the second-stage polymerization in order to avoid the nucleation of secondary particles. TMI was found to retard the polymerization kinetics. The effect of variables, such as the total number of particles, initiator concentration, and the monomer feed rate on polymerization kinetics, was investigated. The composition of the second-stage polymer could be controlled by running the polymerization under monomer-starved conditions. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 685–694, 1998

Seeded emulsion terpolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI®) with acrylic monomers

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a novel bifunctional monomer. It has a double bond and an isocyanate group. The seeded emulsion terpolymerization of TMI with the acrylic monomers, methyl methacrylate and n-butyl acrylate, has been studied. A copolymer of methyl methacrylate and n-butyl acrylate was used as the seed latex. In order to minimize the risk of hydrolysis of TMI, polymerizations were carried out at 40°C using redox initiators. No additional surfactant was added during the second-stage polymerization in order to avoid the nucleation of secondary particles. TMI was found to retard the polymerization kinetics. The effect of variables, such as the total number of particles, initiator concentration, and the monomer feed rate on polymerization kinetics, was investigated. The composition of the second-stage polymer could be controlled by running the polymerization under monomer-starved conditions. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 685–694, 1998

Bulk copolymerization of dimethyl meta‐isopropenyl benzyl isocyanate (TMI®): Determination of reactivity ratios

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a bifunctional monomer with an unsaturation and an isocyanate group. Bulk copolymerizations of TMI with styrene, methyl methacrylate, and n-butyl acrylate were investigated. Polymerizations were carried out to low conversions in sealed test tubes at 70°C. The copolymer composition was determined using Fourier transform infrared (FTIR) spectroscopy. The data were analyzed using the terminal, as well as restricted penultimate, model of copolymerization. The method of Kelen-Tudos was used to calculate the reactivity ratios according to the terminal model. A nonlinear regression analysis was also carried out. Low reactivity ratio values for TMI were obtained for the copolymerizations with styrene and methyl methacrylate as a result of the inability of TMI to undergo homopolymerization. The value was higher for the copolymerization with n-butyl acrylate. Composition diagrams were generated, and the range of TMI concentration in the monomer charge for the preferential incorporation of TMI in the copolymer was identified. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 559–568, 1998

Bulk copolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI�): Determination of reactivity ratios

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a bifunctional monomer with an unsaturation and an isocyanate group. Bulk copolymerizations of TMI with styrene, methyl methacrylate, and n-butyl acrylate were investigated. Polymerizations were carried out to low conversions in sealed test tubes at 70°C. The copolymer composition was determined using Fourier transform infrared (FTIR) spectroscopy. The data were analyzed using the terminal, as well as restricted penultimate, model of copolymerization. The method of Kelen-Tudos was used to calculate the reactivity ratios according to the terminal model. A nonlinear regression analysis was also carried out. Low reactivity ratio values for TMI were obtained for the copolymerizations with styrene and methyl methacrylate as a result of the inability of TMI to undergo homopolymerization. The value was higher for the copolymerization with n-butyl acrylate. Composition diagrams were generated, and the range of TMI concentration in the monomer charge for the preferential incorporation of TMI in the copolymer was identified. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 559–568, 1998

Isocyanate-functionalized latexes: Film formation and tensile properties

Latexes functionalized with isocyanate groups were prepared by carrying out the emulsion terpolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI®) with methyl methacrylate and n-butyl acrylate. The film formation of these latexes and the tensile properties of the resulting latex films were studied. The effect of TMI concentration on the film properties was investigated. The locus of the isocyanate groups in the latex particles was controlled by using different polymerization processes. The locus of the functional groups was found to greatly influence the tensile properties of the latex films. Triethyl amine was used as an external catalyst to cure the TMI polymer films. One-component self-curable systems capable of undergoing crosslinking at ambient temperatures were developed by incorporating small amounts of methacrylic acid into the recipe. These systems exhibited significant improvement in tensile properties upon curing. In addition, the shelf-stability of these latexes was found to be excellent. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1869–1884, 1997

Study of the consumption of TMI® in latex using attenuated total reflectance FTIR (ATR‐FTIR)

Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to study the mechanism for consumption of isocyanate groups from a dimethyl meta-isopropenyl benzyl isocyanate (TMI®) monomer. A series of polystyrene/poly(butyl acrylate-co-TMI) [PS/P(BA-TMI)] core/shell structured latexes with different core/shell ratios were prepared by seeded emulsion polymerization techniques. These latexes were air-dried on ATR-FTIR germanium (Ge) discs while the FTIR spectra were taken during the film-formation process. The amounts of isocyanate moieties which were reacted during polymerization and the film-formation process were determined quantitatively using the FTIR data combined with titration calibration of the isocyanate groups. The thickness of the shell in which the TMI monomer was incorporated was found to be very important in determining the extent of consumption (hydrolysis) of the isocyanate groups during either polymerization or film formation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1967–1973, 1997

Study of the consumption of TMI� in latex using attenuated total reflectance FTIR (ATR-FTIR)

Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to study the mechanism for consumption of isocyanate groups from a dimethyl meta-isopropenyl benzyl isocyanate (TMI®) monomer. A series of polystyrene/poly(butyl acrylate-co-TMI) [PS/P(BA-TMI)] core/shell structured latexes with different core/shell ratios were prepared by seeded emulsion polymerization techniques. These latexes were air-dried on ATR-FTIR germanium (Ge) discs while the FTIR spectra were taken during the film-formation process. The amounts of isocyanate moieties which were reacted during polymerization and the film-formation process were determined quantitatively using the FTIR data combined with titration calibration of the isocyanate groups. The thickness of the shell in which the TMI monomer was incorporated was found to be very important in determining the extent of consumption (hydrolysis) of the isocyanate groups during either polymerization or film formation.

Elastomeric films from structured latexes

A model structured latex that is capable of forming a self-curable elastomeric film under mild temperature conditions was developed. In this model latex system, a small amount of dimethyl meta-isopropenyl benzyl isocyanate (TMI®) was copolymerized with n-butyl acrylate (BA) onto poly(butadiene-co-styrene) [(P(Bd-S)] seed latex particles. In the final stage of the film formation process, the latex particles coalesce with each other, and interdiffusion of PBA-based polymer chains in the shell layers of adjacent structured particles occurs. At this stage, the isocyanate groups in the P(BA-TMI) shell layer would begin to crosslink by either a moisture-cure reaction via trace amounts of water remaining in the latex film or by a post-added crosslinker that contains amine groups. Improved elastomeric properties of the latex film are expected from this kind of “interphase” crosslinking structure. However, latex films prepared from the model P(Bd-S)/P(BA-TMI) core/shell latexes were cracked and brittle, which was explained by the formation of a highly crosslinked/grafted core/shell interphase zone. Saturation of the residual double bonds in the P(Bd-S) seed latex particles by hydrogenation was found to be an effective way to reduce the development of the interphase zone and the degree of crosslinking during the second-stage polymerization. An elastomeric film with good mechanical and anti-aging properties was formed from this hydrogenated-P(Bd-S)/P(BA-TMI) structured latex. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1143–1152, 1997

Emulsion terpolymerization of dimethyl meta‐isopropenyl benzyl isocyanate (TMI®) with acrylic monomers: Process development and kinetics

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a bifunctional monomer possessing a double bond and an isocyanate group. Emulsion terpolymerization of TMI with the acrylic monomers, methyl methacrylate and n-butyl acrylate, was studied. Polymerizations were carried out at 40°C using a redox initiator system in order to minimize the extent of hydrolysis of the isocyanate in the aqueous emulsion environment. The kinetics of the polymerization reaction were investigated. The polymerization rate was found to decrease with increasing TMI concentration. The effects of several preparative variables such as the monomer, surfactant, and initiator concentration on the polymerization kinetics was studied. Several semicontinuous polymerization processes were developed in order to enhance the incorporation of TMI at appreciable rates. These processes also allow us to control the polymer composition, latex particle size, and the locus of isocyanate groups in the latex particle. Process variables such as the mode of initiator addition (batch versus semicontinuous) were found to greatly influence the polymerization behavior. © 1996 John Wiley & Sons, Inc.

Emulsion terpolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI�) with acrylic monomers: Process development and kinetics

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a bifunctional monomer possessing a double bond and an isocyanate group. Emulsion terpolymerization of TMI with the acrylic monomers, methyl methacrylate and n-butyl acrylate, was studied. Polymerizations were carried out at 40°C using a redox initiator system in order to minimize the extent of hydrolysis of the isocyanate in the aqueous emulsion environment. The kinetics of the polymerization reaction were investigated. The polymerization rate was found to decrease with increasing TMI concentration. The effects of several preparative variables such as the monomer, surfactant, and initiator concentration on the polymerization kinetics was studied. Several semicontinuous polymerization processes were developed in order to enhance the incorporation of TMI at appreciable rates. These processes also allow us to control the polymer composition, latex particle size, and the locus of isocyanate groups in the latex particle. Process variables such as the mode of initiator addition (batch versus semicontinuous) were found to greatly influence the polymerization behavior. © 1996 John Wiley & Sons, Inc.

Siloxanes with aliphatic isocyanate groups

Tetramethylcylcotetrasiloxane (D4H) was hydrosilylated with α,α′-dimethyl meta-isopropenyl benzyl isocyanate (m-TMI). The reaction with this commercially available and inexpensive isocyanate produces in 100% yield a well characterized tetrafunctional siloxane-based aliphatic isocyanate useful as a cross-linking agent and as a precursor for star polymers. The silylation reaction can also be carried out with other siloxanes containing SiH groups such as 1,1,3,3-tetramethyldisiloxane yielding siloxanes with terminal isocyanate groups.