Octyl Isocyanate Research Articles

Valorization of hemicellulose waste streams for moisture barrier coatings and hydrophobic films

Replacing plastics with renewable and environmentally friendly substitutes is becoming ever more critical as we begin to realize the consequences of their negative impacts on the environment. Plant polysaccharides are the most abundant biopolymers on Earth, and hemicelluloses like xylan that are enriched in many agro-industrial waste streams have vast potential as eco-friendly building blocks for polymer science and engineering. However, xylan is one of the less studied natural polymers for applications that are relevant to the synthetic plastics and polymeric materials markets. Hemicellulose isolated from viscose and Lyocell fiber mills is largely seen as a waste product due to difficulties arising from the potential for structural heterogeneity and its lack of solubility after enrichment. In this work, we developed a strategy to valorize hemicellulose by functionalization with octyl isocyanate to achieve solubility and thermoplastic/hydrophobic properties. Xylan isolated from dissolving pulp waste streams was successfully functionalized with octyl isocyanate in DMSO at an estimated 79% hydroxyl conversion. Reaction parameters, including temperature, time, and stoichiometry were optimized for each reaction. The resultant carbamates of xylan oligo- and monosaccharides have good solubility in chloroform and impressive hydrophobic film forming properties yet retain the composability properties desired for renewable materials that are envisioned to enter the circular bioeconomy. Functionalization of xylan with an aliphatic chain through formation of an aliphatic carbamate is not expected to harbor the same toxicity or carcinogenic characteristics as the reactive isocyanate it is derived from, and thus should not inherently restrict these materials for use in diverse packaging applications. These modified physical properties show that xylan from agro-industrial waste streams has considerable potential to replace petroleum-based feedstocks in the existing packaging industry. In the future, we will continue to further develop strategies for valorization of these materials.Graphical

Post-Synthetic Modification of a Metal-Organic Framework Glass.

Melt-quenched metal–organic framework (MOF) glasses have gained significant interest as the first new category of glass reported in 50 years. In this work, an amine-functionalized zeolitic imidazolate framework (ZIF), denoted ZIF-UC-6, was prepared and demonstrated to undergo both melting and glass formation. The presence of an amine group resulted in a lower melting temperature compared to other ZIFs, while also allowing material properties to be tuned by post-synthetic modification (PSM). As a prototypical example, the ZIF glass surface was functionalized with octyl isocyanate, changing its behavior from hydrophilic to hydrophobic. PSM therefore provides a promising strategy for tuning the surface properties of MOF glasses.

Cotton fiber modified via N-phenyl anhydride in situ ring-opening polymerization with controllable surface morphology and its wettability

A desired synthetic route of N-phenyl anhydride was proposed, and it was used as a monomer raw material. Poly(amino acid) chains were formed via in situ ring-opening polymerization of the acid anhydride, initiated by the self-assembled amine monomolecular film, and were subsequently grafted on the surface of cotton fibers to create a rough morphology and obtain a low-surface-energy surface. The effects of various experimental conditions on the rough surface structure with microspherical morphology were then studied. Moreover, the morphology of the grafted polymer on the fiber surface was observed by scanning electron and atomic force microscopy, substantiating the correlation analysis of the growth process and formation mechanism of the poly(amino acid) microspheres. On this basis, the poly(amino acid)–cotton fabric surface was modified with octyl isocyanate, which endowed the fabric with lower surface energy and superhydrophobicity. Notably, the water contact angle of the fabric reached 158.2 ± 0.8°. Self-cleaning and oil–water separation tests showed that the prepared superhydrophobic cotton fabrics displayed superior stain resistance and oil–water mixture separation performances. The prepared fabrics are highly rated for physicochemical stability and unaffected wearability, and are expected to broaden the application range of cotton fabrics.

Enhanced antimicrobial activities of polymerized arbutin and its derivatives prepared by oxidative polymerization of arbutin

The amplified antimicrobial activities of poly(arbutin) [poly(arb)] and its 10% octylated derivative [poly(arb)-C810] are described in this paper. Poly(arb) was prepared from monomeric arbutin via oxidative polymerization in an aqueous media, and poly(arb)-C810 was prepared by alkylation of poly(arb) with octyl isocyanate. The minimum inhibitory concentration of arbutin, poly(arb), and poly(arb)-C810 were determined to be 111, 15.2, and 52.6 mg/mL against Escherichia coli and 111, 1.00, and 1.00 mg/mL against StapHylococcus aureus, respectively. The higher antimicrobial activity of polymeric arbutin compared with monomeric arbutin was proposed to be the result of the neighboring effect of phenolic groups of polymers along with the concentration effect of the polymers on the surface of the culture plate, which was proved by ultraviolet–visible spectrophotometry.

Thermal effect of carbamates based polymer on the TiO2 growth

AbstractWe investigated the growth of TiO2 on poly((tetrahydropyran‐2‐yl N‐(2‐methacryloxyethyl) carbamate)‐co‐(methyl 4‐(3‐methacryloyloxypropoxy) cinnamate) (THP‐polymer) using thermal heating, octyl isocyanate (OIC), and glutaraldehyde. It is found that TiO2 can be grown on surfaces terminated with NH2 and O groups from aqueous solution. However, TiO2 did not deposit on CH3 terminated surfaces, due to the low surface energy of these surfaces. Fourier transform infrared spectroscopy and thermogravimetric analysis data showed that the THP functional group can be removed and the surface functional group converted to NH2 by heating the material over 180°C. OIC can then be immobilized on the surface after heating, changing the surface functional group from NH2 to CH3. As TiO2 can be deposited from solution on NH2 terminated, but not CH3 terminated surfaces, THP‐polymer can be used to switch the surface properties by thermal activation and subsequent reaction with OIC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Self-Assembly of Supramolecualr Metallogelator Containing 2-(2′-Hydroxyphenyl) benzoxazole/Zn(II) Chelate

A low molar mass organogelator 1 containing 2-(2'-hydroxyphenyl)benzoxazole (HPB) unit with long alkyl chain was synthesized by the reaction with HPB and octyl isocyanate in THF at room temperature. A new chelate-based organogelator 1-Zn(II) was prepared with the reaction of 1 and zinc(II) acetate in methanol and dichloromethane at mild condition. The gelation ability of organogelator was tested by heating-cooling method in various organic solvents, and the opaque gel was formed from DMF. Well-developed self-assembled structure of organogel was confirmed with field emission-scanning electron microscope (FE-SEM) and transmission electron microscope (TEM), and the optical properties of organogel upon aggregation were monitored by UV-Vis and fluorescence spectroscopy, 1-Zn(II) was self-assembled to the sheet-like structure with the thickness of fully extended length of molecules.

Control of TiO2 Growth Conditions Using Tetrahydropyran Protected Self-Assembled Monolayer and Alkyl Isocyanate

The control of growth condition on tetrahydropyran (THP)–2-carbamate propyl triethoxysilane (TCPES) using thermal heating and octyl isocyanate (OIC) was investigated. can be grown on surfaces terminated with –OH and groups from an aqueous solution of about pH 3. However, did not deposit on the terminated surfaces due to the low surface energy of these surfaces. The –THP functional group can be removed, and the surface functional group can be converted to by heating the material over . OIC can then be immobilized on the surface after heating, changing the surface functional group from to . As can be deposited from a solution on a terminated surface but not a terminated surface, TCPES can be used to switch the surface properties by thermal activation and subsequent reaction with OIC. This approach has the potential to be used for site-selective deposition of on surfaces.

An FTIR investigation of isocyanate skin absorption using in vitro guinea pig skin

Isocyanates may cause contact dermatitis, sensitization and asthma. Dermal exposure to aliphatic and aromatic isocyanates can occur in various exposure settings. The fate of isocyanates on skin is an important unanswered question. Do they react and bind to the outer layer of skin or do they penetrate through the epidermis as unreacted compounds? Knowing the kinetics of these processes is important in developing dermal exposure sampling or decontamination strategies, as well as understanding potential health implications such exposure may have. In this paper the residence time of model isocyanates on hairless guinea pig skin was investigated in vitro using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry. Model isocyanates tested were octyl isocyanate, polymeric hexamethylene diisocyanate isocyanurate (pHDI), polymeric isophorone diisocyanate isocyanurate (pIPDI) and methylenediphenyl diisocyanate (MDI). Isocyanates in ethyl acetate (30 microL) were spiked directly on the skin to give 0.2-1.8 micromol NCO cm(-2) (NCO = -N=C=O), and absorbance of the isocyanate group and other chemical groups of the molecule were monitored over time. The ATR-FTIR findings showed that polymeric isocyanates pHDI and pIPDI may remain on the skin as unreacted species for many hours, with only 15-20% of the total isocyanate group disappearing in one hour, while smaller compounds octyl isocyanate and MDI rapidly disappear from the skin surface (80+% in 30 min). Isocyanates most likely leave the skin surface by diffusion predominantly, with minimal reaction with surface proteins. The significance of these findings and their implications for dermal exposure sampling and isocyanate skin decontamination are discussed.

Anionic polymerization of isocyanates with optical functionalities

Polyisocyanates of 2-[4-(4-nitrophenylazo)- N-ethylphenyl amino]ethoxy carbonyl amino hexyl isocyanate, DR1NCO, and ( s)-(−)-2-methyl-1-butyloxy carbonyl amino hexyl isocyanate, MBI, were synthesized by anionic polymerization using sodium naphthalenide as an initiator in THF at −98°C. In the polymerization reaction, crown ether (15C5) and octyl isocyanate (Oct-NCO) were used to suppress side reactions such as backbiting or chain transfer reaction. In the homopolymerization of DR1NCO, the polymers with high yield (∼94%) were obtained due to suppression of backbiting by 15C5. In the random copolymerization of DR1NCO with MBI, the chain transfer reaction was suppressed due to the low reactivity of anionic chain end induced by octyl isocyanate. The random copolymers showed the optical activity in CD and ORD measurements, and specific rotations increased with increasing the component of MBI.

Phase transitions of poly(octyl isocyanate): Simulation of the e.p.r. spectra of a dry spin-labelled polymer

The basic ideas of a novel way to simulate electron paramagnetic resonance (e.p.r.) spectra of spin-labelled polymers are described. The simulation method has been applied in the analysis of the e.p.r. spectra of dry spin-labelled poly(octyl isocyanate) (POIC). POIC is a semiflexible, helical polymer capable of forming a thermotropic liquid crystalline phase. The spectra of a fractionated POIC sample have been analysed in order to find out how the mobility and flexibility of the chain change with increasing temperature, when the polymer turns from the semicrystalline into the liquid crystalline state. The results imply that the sample contains both helical and random chain sequences through the whole temperature range studied. However, the proportion of the helical sequences is dependent on temperature.

Solvent dependence of the chain flexibility, aggregation and gelation of spin-labelled poly(octyl isocyanate)

A spin-labelled poly(octyl isocyanate) has been synthesized by copolymerizing a nitroxide radical having an isocyanate function, with n-octyl isocyanate. The electron paramagnetic resonance spectra of the labelled polymer in various solvents are sensitive to the local conformation and flexibility of the polyisocyanate chain. The motion of the label is less restricted in a polar solvent (chloroform) than in the non-polar hydrocarbons. Poly(octyl isocyanate) shows a tendency to form aggregates in certain solvents; in solvents with low polarity the aggregation leads to the gelation of the solution. A dipolar interaction between the nitroxide labels is observed in some of the samples. The proximity of the labels is suggested to be dependent not only on the solvent quality but also on the local ordering of the polymer chains.

Solutions and gels of spin-labelled poly(octyl isocyanate) in non-polar hydrocarbon solvents

Chain dynamics and the conformation of poly(octyl isocyanate) (POIC) in solutions and gels have been studied by electron paramagnetic resonance (e.p.i.) spectroscopy using a spin-labelled polymer. The polymer was dissolved in two non-polar solvents, isooctance and cyclohexane. The isooctane solutions form thermoreversible gels, whereas in cyclohexane viscous solutions are obtained. The e.p.r. spectra were analysed as combinations of various spectral modes, one of which reflects the restriction of the label motion by the carbonyl groups in the main chain. The other modes are due to the bending of the chain, i.e. due to chain flexibility. The temperature dependence of the chain flexibility is very different in the two solvents. Melting of the gel of POIC in isooctane is detected as a change from a broad immobilized e.p.r. spectrum to a motionally narrowed triplet spectrum with considerably broadened lines. Gel melting is accompanied by changes in the isotropic coupling constant, as well as by increasing dipolar interactions between the labels in the neighbouring chains. On the other hand, the spectra measured from the polymer dissolved in cyclohexane change only slightly with temperature.

New Approaches for the Preparation of Hydrophobic Heparin Derivatives

A heparin derivative sufficiently lipophilic to be bound to plastics, forming blood‐compatible supports, or to be used as an anticoagulant by transdermal or oral routes would be of great pharmaceutical interest. For such applications, the functional groups within heparin's antithrombin III binding site, responsible for its anticoagulant activity, cannot be modified. Chemistry is described in which lipophilic substituents were attached to the reducing termini of heparin chains. Substituents introduced at this position had a minimal effect on the antithrombin III binding sites found in heparin's interior. These derivatives, with enhanced hydrophobicities, were prepared using two distinctly different approaches. First, octyl isocyanate and octadecyl isocyanate were coupled to the core peptide of peptidoglycan heparin to form octyl‐ and octadecyl‐peptidoglycan heparin. These octyl‐ and octadecyl‐peptidoglycan heparins were then purified by hydrophobic interaction chromatography on phenyl‐Sepharose CL‐4B, demonstrating their enhanced hydrophobicities. Second, the lipophilic acyl hydrazides of various long chain fatty acids were coupled to heparin's reducing end. Caprylic (C8), capric (C10), lauric (C2), and stearic (C18) hydrazide derivatives of heparin were prepared using this approach. Only the stearyl hydrazide derivative of heparin showed a measurable increase in lipophilicity. This result demonstrated that a single small linear C8, C10, or C12aliphatic chain was ineffective in enhancing the hydrophobicity of the highly negative, polyanionic heparin molecule. Two lipophilic chains, lauryl (C12) and stearyl (C18), were then coupled to a single heparin chain, resulting in a heparin derivative having enhanced hydrophobicity. All the heparin derivatives prepared in this study maintained some of their anticoagulant activity.

Neuroleptics of the 8-methylthio-10-piperazino-10,11-dihydrodibenzo[b,f]thiepin series: New compounds and new procedures

Heating of 8-methylthiodibenzo[b,f]thiepin-10(11H)-one with mono-p-toluenesulfonates of 1-methylpiperazine and piperazine in vacuo led in good yields to the enamines IX-XI, the first of which was reduced with zinc and acetic acid to the base I (methiothepin). The ester III(oxyprothepindecanoate) was obtained by reaction of the amino alcohol II (oxyprothepin) with decanoic acid in the presence of N,N'-carbonyldiimidazole and by substitution of 10-chloro-8-methylthio-10,11-dihydrobenzo[b,f]thiepin with 1-(3-decanoyloxypropyl)piperazine. The substitution reaction of the same chloro compound with piperazine gave two stereoisomeric 1,4-disubstituted piperazines V. Reaction of the amino alcohol II with octyl isocyanate afforded the carbamate VI, an isoster of oxyprothepin decanoate (III). This substance showed in the test of antiapomorphine activity in dogs the properties of a long-acting antiemetic. Two new potential metabolites (XII, XIII) of compounds I-III were synthesized and new pharmacological data are given for two further potential metabolites (XIV, XV) of oxyprothepin (II).

Alkyl isocyanates as active site-specific reagents for serine proteases. Location of alkyl binding site in chymotrypsin by X-ray diffraction.

The structure of octylcarbamoyl-alpha-chymotrypsin to a resolution of 3.0 A is described. The n-octyl side chain of the active site directed irreversible inactivator octyl isocyanate is bound exclusively in the hydrophobic substrate binding pocket. The n-octyl isocyanate forms a planar urethane bond with the Ser-195 Ogamma and extends approximately 1 A deeper into the hydrophobic pocket than the indolyl group of indoleacryloyl-alpha-chymotrypsin (Henderson, R. (1970), J. Mol. Biol. 54, 341). All the structural changes are essentially identical with those observed in indoleacryloyl-alpha-chymotrypsin including the observation of a hydrogen bonded water molecule between the carbonyl oxygen of the octylcarbamoyl group and the imidazole group of His-57. The observed mode of n-octyl alkyl binding to chymotrypsin is consistent with the hypothesis proposed earlier (Brown, W. E. and Wold, F. (1973), Biochemistry 12, 828).

Alkyl isocyanates as active site-specific inhibitors of chymotrypsin and elastase.

Alkyl isocyanates react specifically with the two serine proteinases, chymotrypsin and elastase, to yield inactive enzyme derivatives containing 1 male of reagent per mole of enzyme. Octyl isocyanate inactivates chymotrypsin only, while butyl isocyanate inactivates both enzymes but shows greater efficiency toward elastase than toward chymotrypsin. These reagents may thus represent unique chemical "yardsticks" for the measurement of the relative dimensions of the active sites of the two very similar enzymes.