Dimethyl Benzyl Isocyanate Research Articles

In-situ compatibilization of polyamide 6/polycarbonate blends through interfacial localization of silica nanoparticles

Nanoparticles are used to compatibilize immiscible polymer blends. The key to success is to localize nanoparticles at polymer-polymer interfaces. This work aims to use silica nanoparticles (SiO2) to compatibilize polyamide 6 (PA6)/polycarbonate (PC) blends. The strategy to ensure the interfacial localization of the SiO2 in the blends is to graft a methacrylic monomer onto the SiO2 and then copolymerize this methacrylic monomer with styrene (St) and 3-isopropenyl-α,α′-dimethylbenzyl isocyanate (TMI). When PA6 and PC are blended in the melt in the presence of the above surface modified SiO2 (denoted as SiO2-PST), PA6 chains are grafted onto the SiO2-PST to form PA6-SiO2-PST through a coupling reaction between the terminal amine group of the PA6 and the isocyanate moieties of the PST grafts which are partially miscible with the PC. It is shown that an optimum TMI content allows for the SiO2-PST to be preferentially localized at the interfaces between the PA6 and PC. This leads to a significant decrease in the PC domain diameter from 1.6 μm to 0.6 μm without and with the SiO2-PST, respectively. The presence of the SiO2-PST (0.5 wt% with an optimum TMI content) increases the tensile strength of the PA6/PC (70/30 by weight) from 64.1 to 79.6 MPa, the elongation at break from 84.7 to 284.7%, and the notched Charpy impact strength from 10.3 to 29.4 kJ/m2.

Changes in colour and mechanical properties of wood polypropylene composites on natural weathering

This comparative study focused on understanding the effect of coupling agent and particle size on weath-ering behaviour of wood polypropylene composite. Two coupling agents, namely maleic anhydride grafted polypropylene and m-TMI (m-Isopropenyl-α,α− dimethylbenzyl isocyanate) grafted polypropylene were used in preparation of the composites. The composites were exposed to outdoor conditions for one year and changes in surface colour and mechanical properties were measured after 2, 4, 8 and 12 months of natural weathering. During the initial four months of weathering considerable colour change was observed with increase in light-ness. Mechanical properties were unaffected largely for the initial four months and thereafter started declining. Overall, tensile strength decreased by about 15 % and flexural strength decreased by about 8 % after one year of weathering. The flexural modulus also decreased by about 10 %. Wood particle size was found to affect the aesthetic and strength of the composites after natural weathering. Coupling agents had a positive impact on mechanical properties however their influence on weathering degradation was not noticeable

Synthesis of Pendant Amine Functional Methyl Acrylate/Acrylonitrile Copolymers and Reactively Compatibilized Blends with Poly(Ethylene)

Acrylonitrile (AN)-containing copolymers have not been widely considered as barrier dispersed phases in blends with poly(ethylene) (PE), despite the versatility in their synthesis (i.e. controlled radical radical polymerization). To use such copolymers in PE, compatibilization is essential to obtain the desired morphology and thus we made a primary amine functional monomer, IDBA (3-isopropenyl-α,α–dimethylbenzylamine), with minimal purification steps, high yield (up to 76%) and high conversion (98%) in multi-gram batches from a cheap, commercially available precursor m-TMI (3-isopropenylα,α−dimethylbenzyl isocyanate). Terpolymers of AN, IDBA, MA (methyl acrylate) and AN (acrylonitrile) were then synthesized in DMF solution by conventional radical polymerization (number average molecular weight

2-(Perfluorooctyl) Ethyl Acrylate (PFOEA) 및 m-Isopropenyl-α, α-Dimethylbenzyl Isocyanate (TMI)가 함유된 발수체 합성 및 특성연구

Abstract: A series of terpolymers based on stearyl methacrylate (SMA), n-methyol acrylamide (n-MAM), and 2-(perfluorooctyl) ethyl acrylate (PFOEA) were synthesized by changing PFOEA contents up to 8 wt% in order to obtain optimal water-repellent properties. In addition, various contents of m-isopropenyl-α,α’-dimethylben-zyl isocyanate (TMI) from 1 to 4 wt% were added to the above terpolymers with 4 wt% of PFOEA content. The emulsion polymerization was carried out using tridecyl alcohol (EO) 7 (TDA-7) as a nonionic surfactant, alkyl dimethyl amine derivatives (ADAD) as a cationic surfactant, and 2,2’-azobis(2-amidinopropane dihy-drochoride) (AAPDL) as an initiator. The synthesized copolymers were characterized by FT-IR spectroscopies, contact angle, surface energy, and water-repellency. Surface and thermal properties were analyzed by SEM, TGA, and DSC. It was found that water repellency increased with increasing the contents of PFOEA and TMI. Keywords: emulsion polymerization, water-repellency, surface modification, thermal property

Synthesis and Properties of Long-Chain Aromatic Telechelic Monodispersed Diols Radical-Initiated, Addition of 2-Mercaptoethanol onto α, ω Nonconjugated Dienes

The synthesis of aromatic telechelic mono dispersed diols produced from the radical-initiated addition reaction of a twofold excess of 2-mercaptoethanol onto original α,ω nonconjugated dienes reaction is presented. These novel α,ω nonconjugated dienes were prepared by addition reaction of m-isopropyl α,α′dimethyl benzylisocyanate with mono dispersed telechelic diols obtained by fractionation of oligo(ethylene terephthalate)s. In these cases, the long chain α,ω diols were produced selectively and quantitatively. The products are soluble in most organic solvents in contrast to classical oligo (ethylene terephthlate)s and posses a lower glass transition and melting temperatures. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Figures S1-S3.

Cellular compatibility of copolymer hydrogels based on site‐selectively‐modified chitosan with poly(N‐isopropyl acrylamide)

AbstractThis research synthesized graft copolymers of chitosan‐g‐poly(N‐isopropyl acrylamide) (CS‐g‐PNIPAAm) by UV‐initiated free‐radical polymerization of NIPAAm monomer to CS selectively at the C‐6 position of pyranose ring. First, amino groups in CS were protected by reaction with phthalic anhydride (PA) to form PACS. The degree of phthaloylation was carefully controlled to ensure that most amino groups were protected, and only a very small amount of hydroxyl groups were reacted. In the second step, the vinyl functional group was introduced to the PACS by reaction with a vinyl compound containing an isocyanate group (3‐isopropenyl‐αα′‐dimethylbenzyl isocyanate), through the urethane linkage with hydroxyl groups at the C‐6 position. The phthaloyl groups were then removed by hydrazine to recover the amino groups in CS. Finally, PNIPAAm was grafted to the vinyl CS at the C‐6 position by UV‐initiated free‐radical polymerization. The synthesized CS‐g‐PNIPAAm copolymers were confirmed to have a structure of an AB‐crosslinked graft copolymer. Respectively, these copolymer hydrogels exhibited pH‐ and thermal‐responsive swelling properties in an aqueous solution due to their CS and PNIPAAm components. The test of cell viability with L929 fibroblast revealed that the CS‐g‐PNIPAAm copolymers having a grafting ratio lower than 1.7 had cellular compatibility as good as pure CS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Unexpected alternating radical copolymerization of chlorotrifluoroethylene with 3‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate

AbstractThe radical solution copolymerization of hexafluoropropylene, chlorotrifluoroethylene (CTFE), vinylidene fluoride, and tert‐butyl‐α‐trifluoromethylacrylate with different monomers bearing isocyanato groups such as allyl isocyanate, 3‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate (m‐TMI), and 2‐isocyanatoethyl methacrylate, initiated by 2,5‐bis(tert‐butylperoxy)‐2,5‐dimethylhexane were studied. Several of these radical copolymerizations were not successful in contrast to that of CTFE with m‐TMI, although m‐TMI monomer does not homopolymerize under radical initiation. The resulting poly(CTFE‐co‐m‐TMI) copolymers were characterized by 1H and 19F nuclear magnetic resonance and Fourier transform infrared spectroscopy and their compositions assessed by elemental analysis. The reactivity ratios of both comonomers were determined by linearization methods of Fineman‐Ross, Kelen‐Tüdös for low conversions of monomers, and by the extended Kelen‐Tüdös method for high monomer conversions. The average values of the monomer reactivity ratios, rCTFE and rm‐TMI, were 0.076 and 0.034 at 130 °C, respectively, depending on these monomer conversions and the applied methods of calculation. In all cases, rCTFE × rm‐TMI product was close to zero, which indicates that poly(CTFE‐co‐m‐TMI) copolymers exhibit a high tendency toward alternation. This was also confirmed by the Igarashi's theory which revealed a high content of CTFE‐m‐MTI heterodyads. The Q and e values for m‐TMI monomer were also assessed (Qm‐TMI = 0.007 and em‐TMI = 0.99). As well as this kinetics of copolymerization, several properties of the obtained fluorofunctional copolymers such as molecular weights (ranging from 1500 to 8200 g mol−1), molecular weight distributions (from 1.2 to 2.1) were also investigated. Their thermal properties revealed satisfactory thermal stability (higher than 250 °C). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2681–2697, 2010

Influence of Compatibiliser and Wood Flour on the Non-Isothermal Crystallisation Behaviour of Polypropylene Composites

The influence of m-isopropenyl-±,±dimethylbenzyl isocyanate grafted polypropylene (m-TMI-g-PP) and wood flour (WF) on the non-isothermal crystallisation behaviour of wood flour/polypropylene (WF/PP) composites was studied by differential scanning calorimetry. The crystalline morphology of PP was observed by polarised optical microscopy. The results demonstrated that the wood flour induces nucleation, while m-TMI-g-PP could greatly reduce the number of nucleation sites of the WF. Avrami analysis showed that the non-isothermal crystallisation of PP and its composites followed the Avrami equation. The activation energy was calculated by using the Kissinger method, and the values were 253.3, 197.4 and 203.1kJ·mol-1 for PP, WF/PP and WF/m-TMI-g-PP/PP, respectively. This proved the nucleation effect of WF; the effect was much smaller in the presence of compatibiliser. The results indicate that the presence of m-TMI-g-PP generates a compatibilisation phenomenon, which leads to a reduction in the crystallisation rate, crystallisation temperature and crystallinity, and an increase in activation energy of PP compared with WF/PP composite.

Reversible addition–fragmentation chain transfer graft copolymerization of styrene and m‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate from polypropylene lanterns: Solid phases for scavenging applications

AbstractThe γ‐initiated reversible addition–fragmentation chain transfer mediated free‐radical graft copolymerization of styrene and m‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate (TMI) from a polypropylene (PP) solid phase was performed with cumyl phenyldithioacetate (CPDA) as the chain‐transfer agent. The initial CPDA concentration was 8 × 10−3 mol L−1. Polymerizations were performed with a dose rate of 0.18 kGy h−1 at the ambient temperature. Initial comonomer mixtures with 15, 30, and 50 mol % TMI were used. Depending on the amount of TMI in the initial comonomer mixture, the plot of the grafting ratio versus the time showed two grafting regimes (for 15 and 50 mol % TMI) or one (for 30 mol % TMI). Scavenger lanterns with 15 and 50 mol % TMI featured two isocyanate loading regimes, the second with higher loading capacities. The scavenger lanterns with 30 mol % TMI showed a linear loading capacity over the full grafting ratio. A maximum loading capacity of 110 μmol per scavenger lantern was achieved with 50 mol % TMI at a grafting ratio of approximately 60 wt %. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 857–864, 2006

Effect of a natural magnesium silicate treated with a new coupling agent on the properties of ethylene–propylene–diene rubber compounds

AbstractThe behavior of sepiolite (magnesium silicate with a microfibrillar morphology) as a filler in ethylene–propylene–diene compounds was studied. A new coupling agent, meta‐isopropenyl dimethyl benzyl isocyanate, was used. The effect of the filler modified by meta‐isopropenyl dimethyl benzyl isocyanate on the physical properties was improved with respect to other fillers and commercial silane coupling agents under the same conditions. In addition to a smoother surface, the flow behavior of compounds filled with sepiolite, on account of its fibrous morphology, was better than that obtained with other fillers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1489–1493, 2004

Crab Shell Chitin Whiskers Reinforced Natural Rubber Nanocomposites. 3. Effect of Chemical Modification of Chitin Whiskers

The purpose of this study was to chemically modify the surface of chitin whiskers and to investigate the effect of the incorporation of these modified whiskers into a natural rubber (NR) matrix on the properties of the ensuing nanocomposite. Different chemical coupling agents were tested, namely, phenyl isocyanate (PI), alkenyl succinic anhydride (ASA) (Accosize 18 from American Cyanamid), and 3-isopropenyl-alpha,alpha'-dimethylbenzyl isocyanate (TMI). The extent of chemical modification was evaluated by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and surface energy analysis. After chemical modification, nanocomposite films were obtained using a toluene natural rubber solution in which the whiskers were dispersed. Their mechanical properties were found to be inferior to those of unmodified chitin/NR composites presented in our previous study. In fact, even though there is an increase in filler-matrix interaction as a result of chemical modification of the chitin whiskers, this does not contribute to the improvement in the mechanical properties of the resulting nanocomposite. It is concluded that this loss of performance is due to the partial destruction of the three-dimensional network of chitin whiskers assumed to be present in the unmodified composites.

Study of photocrosslinkable polysiloxanes bearing gem di-styrenyl groups: Synthesis and thermal properties

The synthesis of photocrosslinkable polysiloxanes containing gem di-oxaalkylene styrenyl groups and gem di-urethane-α-methyl styrenyl groups has been performed by copolycondensation of α,ω-dihydroxy polydimethyl siloxanes and dichlorosilanes bearing either cyclic acetal groups or Si–H groups (onto which the cyclic acetal groups are further added) and dichlorosilanes bearing alkyl groups. The introduction of styrenyl groups was then achieved by hydrolysis of the acetal groups into the corresponding alcohols followed by reaction with chloromethyl styrene or with 3-isopropenyl-α,α- dimethylbenzyl isocyanate. The structure of the different products synthesized was determined by IR, 1H, 13C and 29Si NMR spectroscopies. The thermal properties of the polysiloxanes bearing gem di-styrenyl groups have been studied at low and high temperatures. These products have been crosslinked under UV, in the presence of a cationic photoinitiator, and showed very good release paper properties.

Synthesis and characterization of an isocyanate functionalized polyhedral oligosilsesquioxane and the subsequent formation of an organic-inorganic hybrid polyurethane.

Organic-inorganic hybrids are an important class of new materials that offer improved thermal and mechanical properties over normal polymers. They may be produced by either the sol-gel route or through the use of inorganic compounds possessing reactive functional groups. Polyhedral oligosilsesquioxanes (POSS) are completely defined molecules of nanoscale dimensions that may be functionalized with reactive groups suitable for the synthesis of new organic-inorganic hybrids. Here we report the synthesis and characterization of a novel POSS possessing eight isocyanate groups via the hydrosilylation of octakis(hydridodimethylsiloxy)octasilsesquioxane (Q8M8H) and m-isopropenyl-alpha,alpha'-dimethylbenzyl isocyanate (m-TMI). The suitability of this new macromer to the synthesis of a organic-hybrids has been explored by forming a new type of highly cross-linked polyurethane elastomer via reaction of the macromer with poly(ethylene glycol) using dibutyltin dilaurate catalyst.

Free‐radical copolymerization of styrene and m‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate studied by 1H NMR kinetic experiments

AbstractThe free‐radical copolymerization of m‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate (TMI) and styrene was studied with 1H NMR kinetic experiments at 70 °C. Monomer conversion vs time data were used to determine the ratio kp × kt−0.5 for various comonomer mixture compositions (where kp is the propagation rate coefficient and kt is the termination rate coefficient). The ratio kp × kt−0.5 varied from 25.9 × 10−3 L0.5 mol−0.5 s−0.5 for pure styrene to 2.03 × 10−3 L0.5 mol−0.5 s−0.5 for 73 mol % TMI, indicating a significant decrease in the rate of polymerization with increasing TMI content in the reaction mixture. Traces of the individual monomer conversion versus time were used to map out the comonomer mixture composition drift up to overall monomer conversions of 35%. Within this conversion range, a slight but significant depletion of styrene in the monomer feed was observed. This depletion became more pronounced at higher levels of TMI in the initial comonomer mixture. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1064–1074, 2002

Kinetics and thermal analysis of copolymerization ofm-isopropenyl-?,??-dimethylbenzyl isocyanate with styrene

The copolymerizations of m-isopropenyl-α,α'-dimethylbenzyl isocyanate (m-TMI) with styrene (STY) was investigated. The weight conversion of the copolymerization reaction increased as the duration of copolymerization increased. The reaction temperature was maintained between 60 and 75°C. Molecular weights of the copolymers decreased with increasing molar fraction of m-TMI in the feed. This study obtained reactivity ratios, Alfrey-Price parameters, Mark-Houwink constant, characteristic ratio, thermal degradation activation energy, difference of reactive propagation activation energy, and intrinsic viscosity for the copolymers. The copolymers were characterized by using elemental analysis (EA), gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. The copolymer chains in solution were observed to have a high degree of stiffness and a lack of rotational freedom.

Preparation of macromolecular tracers and their use for studying the residence time distribution of polymeric systems

AbstractIn this study, an easy route was developed to incorporate antracene moieties in polymer chains. It consisted of copolymerizing the monomer of a polymer of interest with 3‐isopropenyl‐α, α'‐dimethylbenzyl isocyanate (TMI) and then reacting the isocyanate‐bearing polymer with 9‐(methylamino‐methyl)anthracene. Such an antracene‐bearing polymer was then used as a tracer (macrotracer) to determine the RTD function of polymers in a twin screw extruder and compared with an antracene as a microtracer. As long as the tracers were well mixed with a polymer of interest and the resulting mixture had the same geometrical form as the polymer before they were charged to the flow stream, the differences between the microtracer and the macrotracer were not reflected in the measured RTD distribution. A variation in the feed rate (Q) or screw speed (N) changes both the RTD and the intensity of axial mixing. On the other hand, for a given but small Q/N, commonly called specific throughput, variations in Q and N change the RTD but not the intensity of axial mixing. When it is small, Q/N can be used as an operating parameter to separate the effect of the residence time from that of mixing for a small Q/N.

Cationic copolymerization of styrenes with an isocyanate-bearing homologue

The cationic homopolymerization of the isocyanate monomer 3-isopropenyl-α,α′-dimethylbenzyl isocyanate ( 1a) as well as its copolymerization with styrene ( 1b) and a-methylstyrene ( 1c) were studied. The syntheses involved the use of titanium tetrachloride in methylene chloride at low temperature. Apart from showing that it is possible to homopolymerize 1a, copolymers with less than 30 mol% of 1a were prepared and thoroughly characterized. They had a very wide molecular weight distribution ( I p ∼ 4) and their T g's followed Fox's equation. These highly reactive copolymers were synthetized in view of coupling them with cellulosic fibres.

Cationic copolymerization involving NCO-bearing monomers and reaction of the ensuing materials with the superficial hydroxy groups of cellulosic fibres

This paper describes the cationic polymerization of 3-isopropenyl-α,α′-dimethylbenzyl isocyanate (TMI) and its copolymerization with isopropenylbenzene (IPB) in order to synthesize materials with varying amounts of NCO side groups. These polymers were characterized by FTIR, 1H-NMR, elemental analysis and DSC. Their structure showed an essentially random incorporation of TMI. Preliminary reactions of the copolymers with cellulosic fibers are also reported.

Synthesis and characterization of new monomers containing UV-absorber function

Two new monomers, 2-hydroxy-4-benzophenonyl allyl carbamate and 2-hydroxy-4-benzophenonyl m-isopropenyl-α,α′-dimethyl-benzyl carbamate, were synthesized by the direct addition reaction of 2,4-dihydroxybenzophenone (DHBP) to allyl isocyanate (AI) or m-isopropenyl-α,α′-dimethylbenzyl isocyanate ( m-TMI) in the presence of dibutyltin dilaurate (DBTDL) catalyst at 80°C. The structure of these two monomers was characterized by FT-IR, 1H-NMR, UV-spectra, XPS, MS and elemental analysis. The properties of these two monomers are also described.

Preparation and characterization of new monomers containing N′-2,2,6,6-tetramethyl-4-piperidyl urea

Two new monomers, N-allyl, N′-2,2,6,6-tetramethyl-4-piperidyl urea (monomer-1) and N- m-isopropenyl- α, α′-dimethyl benzyl, N′-4-2,2,6,5-tetramethyl-4-piperidyl urea (monomer-2), were prepared by direct addition reaction of 4-amino-2,2,6,6-tetramethyl piperidine (ATMP) to allyl isocyanate (AI) and m-isopropenyl- α, α′-dimethyl benzyl isocyanate ( m-TMI) at room temperature without catalyst. The structures of these two monomers were characterized by FT-IR, 1H-NMR, XPS, MS and elemental analysis. The properties of these monomers are also described.