Poly Octadecyl Methacrylate Research Articles

Elucidating the Structure–Property Relationship of Pour Point Depressants: The Case of Polyoctadecyl Methacrylate

Elucidating the Structure–Property Relationship of Pour Point Depressants: The Case of Polyoctadecyl Methacrylate

Excitation-wavelength-dependent fluorescent organohydrogel for dynamic information anti-counterfeiting

Anti-counterfeiting labels with various fluorescent colors are of great importance in information encryption-decryption, but are still limited to static information display. Therefore, it is urgent to develop new materials and encryption-decryption logic for improving the security level of secret information. In this study, an organohydrogel made up of poly(N,N-dimethylacrylamide) (pDMA) hydrogel network and polyoctadecyl methacrylate (pSMA) organogel network that copolymerized with two fluorophores, 6-acrylamidopicolinic acid moieties (6APA, fluorescent ligand) and spiropyran units (SPMA, photochromic monomer), was prepared by a two-step interpenetrating method. As UV light of 365 nm and 254 nm can both cleave Cspiro-O bonds of SPMA, and the green fluorescence of 6APA-Tb3+ can only be excited by 254 nm light, the organohydrogel displays yellow and red under the irradiation of 254 nm and 365 nm, respectively. In addition to wavelength selectivity, these two fluorophores are thermal-responsive, leading to the fluorescence variation of the organohydrogel during heating process. As a result, secret information loaded on the organohydrogel can be decrypted by the irradiation of UV light, and the authenticity of the information can be further identified by thermal stimulation. Our fluorescent organohydrogel can act as an effective anti-counterfeiting label to improve the information security and protect the information from being cracked.

Regulating Aggregated Structures in Organohydrogels for On-Demand Information Encryption

As one of the most promising candidates for dynamic information storage, intelligent gels with tunable optical properties under external stimuli have received great attention. The implementation of transparency variation for information display is a favorable and versatile strategy but still faces the challenge of on-demand encryption-decryption. Herein, an optical tunable organohydrogel is prepared, which has interpenetrating heterogeneous networks consisting of hydrophilic poly(N,N-dimethylacrylamide) (PDMA) and hydrophobic polyoctadecyl methacrylate (PSMA). The long alkane side chains of PSMA endow the organohydrogel with the capacity of crystallization-melting transitions under the stimulus of heat, accompanied by transparent-opaque switching. In addition, the variations of transparency can also be achieved by water-induced hydrophobic association and microphase separation, resulting from the unique heterogeneous networks of the organohydrogel. Based on the abovementioned two aggregated structures, various pieces of information can be loaded on the organohydrogel by light writing or water printing with the assistance of masks. The coded information can be encrypted and decrypted by solvent replacement and temperature switching. This elaborately designed organohydrogel can act as an effective communication platform with an improved security level and ignite the sparks of developing novel information storage materials.

Heterogeneous Fluorescent Organohydrogel Enables Dynamic Anti‐Counterfeiting

AbstractFluorescent patterns showing the unique color change in response to external stimuli are of considerable interest for their applications in anti‐counterfeiting. However, there is still a lack of intelligent fluorescent patterns with high‐security levels, presenting a dynamic display of encrypted information. In this study, a fluorescent organohydrogel is fabricated through a two‐step interpenetrating technique, leading to the co‐existence of naphthalimide moieties (DEAN, green‐yellow fluorescent monomer) contained Poly(N,N‐dimethylacrylamide) (PDMA) hydrogel network and Polyoctadecyl methacrylate (PSMA) organogel network bearing spiropyran moieties (SPMA, photochromic monomer). Due to the unique heterogeneous networks, the fluorescence color goes through a continuous change from green to yellow to red via the fluorescence resonance energy transfer (FRET) process with the extension of irradiation time. In addition, when H+ is introduced into the system, SP units exhibit transformation into the protonated merocyanine (MCH+) rather than merocyanine (MC) under UV light, which inhibits the FRET process. By selectively being treated with H+, the fluorescent organohydrogel can act as an effective platform for encrypting secret information, making them more difficult to forge.

Design and synthesis of microcapsules with cross-linking network supporting core for supercooling degree regulation

A novel microencapsulated composite phase change materials (MCPCMs) with low-supercooling was designed using melamine formaldehyde resin (MF) as the shell via in-situ polymerization. The composite phase change materials (CPCMs) were composed of low cross-linked polyoctadecyl methacrylate (C-PODMA) as solid–solid PCM and n-octadecane (C18) as solid–liquid PCM, respectively. The C-PODMA can be used not only as a support material, but also as an energy storage material. In this work, the effects of C-PODMA with different cross-linking degree, C18/C-PODMA mass ratios and particle size on the performance of cross-linking network supported microcapsules (CS-MCPCMs) were investigated in detail. The results showed that the spherical CS-MCPCMs had been successfully prepared. During the synthesis process, the crystal transformation and heterogeneous nucleation caused by C-PODMA can inhibit the supercooling degree of CS-MCPCMs to some extent, which can decrease by 3.7℃ ∼ 8.3℃ and increase the crystallization temperature by 1.0℃ ∼ 2.6℃. At the same time, the thermal decomposition temperature of CPCMs increased by 11.6℃ ∼ 34.6℃ and the energy storage efficiency of CS-MCPCMs was enhanced to 84.2%. It also has relatively high latent heat and satisfactory 150 thermal cycle stability. CS-MCPCMs has broad application prospects in heat storage textiles, forming processing and energy saving building materials.

Polyoctadecyl methacrylate brushes via surface‐initiated atom transfer radical polymerization

The synthesis of poly(octadecyl methacrylate) brushes on planar Si substrates using surface‐initiated atom transfer radical polymerization (SI‐ATRP) is reported. SI‐ATRP of octadecyl methacrylate from a silane initiator‐modified Si substrate yielded well‐defined homopolymer brushes of varying molar mass (5000–38 000 g mol−1) and film thickness from around 2 to 20 nm. Correlation of both free polymer molar mass and brush thicknesses confirmed controlled surface‐initiated ATRP from these modified surfaces. By optimization of brush molar mass, film thickness and thin‐film processing, we observed side chain crystallization of tethered poly(octadecyl methacrylate) chains, resulting in the formation of lamellar morphologies with high‐aspect‐ratio nanofibers. Copyright © 2013 John Wiley & Sons, Ltd.

Numerical simulation of contraction and expansion flows of Langmuir monolayers

Langmuir monolayers consist of amphiphilic molecules at the air–water interface and can be modeled as two-dimensional fluids. Earlier experiments [D.J. Olson, G.G. Fuller, J. Non-Newtonian Fluid Mech. 89 (2000) 187–207] on 4:1 contraction and 4:1 expansion flows have been simulated using an integral constitutive equation of the K-BKZ type, suitably modified to account for strain-thickening in the planar extensional viscosity. The model has been used to fit linear viscoelastic data ( G′ and G″) and the shear viscosity ( η S ), while the amount of strain-hardening is assumed, due to lack of experimental data. The simulations are in good agreement with the experiments on Newtonian monolayers, which show no vortices in the contraction but large inertial vortices in the expansion. For the viscoelastic monolayer (a poly-octadecyl methacrylate or PODMA), the opposite is true. The contraction flow shows vortices, while in the expansion flow the vortex activity is substantially reduced compared with the Newtonian one. The viscoelastic behavior is well captured by the model, provided that substantial strain-thickening is exhibited by the monolayer in planar extension. The latter behavior is very much like that for a branched LDPE melt, which also shows big vortices due to strain-hardening in planar as well as in uniaxial extension.

Comparison of adsorption behavior of two Mytilus edulis foot proteins on three surfaces

The sea mussel Mytilus edulis fabricates a hold-fast (an adhesive plaque) from a proteinaceous mixture that it extrudes into a cavity formed by an organ called the ‘foot’. A family of four proteins in the mixture known as M. edulis foot proteins (Mefp 1–4) have been purified to homogeneity. Mefp-1 and 2 are the most well-characterized and most easily purified members of the Mefp family. They constitute about 5 and 25% of the content of the plaque, respectively. It has been proposed that Mefp-1 mediates bonding to the intended substratum while Mefp-2 serves more as a structural component. In order to provide data relevant to this hypothesis, the adsorption behavior of Mefp-1 and 2 was compared on three surfaces using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Surfaces were germanium (Ge), polystyrene (PS) or poly(octadecyl)methacrylate (POMA). Polymer surfaces were prepared by spin casting onto the flat face of Ge trapezoidal internal reflection elements (IRE). Adsorption behavior was characterized by analyzing the kinetics of adsorption using a double exponential fit. The data indicate that the adsorption behavior of Mefp-1 and 2 is similar on the three surfaces both in terms of rate of adsorption and surface coverage attained over a short (<60 min) time period.

Polyvinylpyridine with polyoctadecylmethacrylate and polyvinylstearate mixtures in monolayers

At the W/A and W/O interphases, mixed monolayers were studied, consisting of a polymer with ionizable polar groups and a nearly “horizontal” disposition, poly-2-vinylpyridine (PVP), and non-ionic polymers with side chains with a “vertical” disposition with respect to the interphases, polyvinylstearate (PVS) and polyoctadecylmethacrylate (POMA), at 15, 25 and 35 °C.

Orientation and compatibility in monolayers: II. Mixtures of polymers

Pressure area isotherms at the water-air and water- n-hexane interfaces are reported for the following polymers: polymethylmethacrylate (PMMA), polyvinylacetate (PVA), polypropylmethacrylate (PPMA), polyvinylstearate (PVS), and polyoctadecylmethacrylate (POMA). The comparison of the experimental data with the bidimensional state equation deduced theoretically (Huggins equation) and ellipsometric measurements allows us to conclude that PMMA, PVA, and PPMA have, at the water-air interface, a “horizontal disposition,” while PVS and POMA have components that are “perpendicularly oriented” at the interface. The surface areas as a function of molar ratios, the “collapse pressure,” and the surface compressional modulus, for the bidimensional systems: PMMA-PPMA, PVS-POMA, PMMA-POMA, and PVA-PVS show the compatibility between macromolecules having the same orientation at the interface and the incompatibility between macromolecules having different orientation. The study of the water- n-hexane pressure area isotherms for the systems PMMA-PPMA and POMA-PVS shows that the main factor which determines the compatibility, at the water-air interface, is the interaction among hydrophobic chains.

The effect of crystallization conditions on thermodynamic characteristics of melting of certain comb-like polymers

Curves of the melting of three comb-like polymers, polyvinyl stearate, polyhexadecyl acrylate and polyoctadecyl methacrylate differing thermal prehistory have been investigated, using differential scanning calorimetry. It was found that all three polymers share the common feature of crystallizing in two different forms. The low temperature form results from quenching the polymers from solutions, while the high temperature form appears in the case of isothermal crystallization in the vicinity of the melting region. Distances between the corresponding endotherms of melting depend on temperature and on the time of isothermal crystallization, and do not exceed 5°.

Surface Chemistry of High Polymers. I. Non-electrolytic Flexible Linear Polymers at Air/Water Interface

Abstract The surface films of some linear non-electrolytic polymers such as polyvinyl acetate, polyvinyl stearate and copolymers between them were studied at the air/water interface by measuring surface pressure, and surface potential in relation to the area occupied per monomer. The surface concentration was changed by two different methods, namely by the compression with barrier and by the successive addition by injection with micrometer syringe. Polyvinyl acetate gave the film of expanded type and was hardly affected by its degree of polymerization. Polyvinyl stearate gave the film of coherent type and its F—A curve resembled that of polyoctadecyl methacrylate. The copolymer with moderate content of vinyl stearate showed the smaller limiting area per monomer than polymers of its constituents. The results were discussed in relation to the molecular model and to the methods adopted to change the surface concentration.