Chemical modification of chlorinated rubbers. II. Study of chlorinated natural rubber modified by amino–esters

The synthesis of ethyl-11-aminoundecanoate and ethyl-3-aminobutyrate and the chemical modification of chlorinated natural rubber by these amino–esters were investigated in order to find useful materials for long-life antifouling paints free from toxic moieties. Detailed reactions and fractionation schemes are described for isolating pure products; their structure was characterized by IR and NMR spectrometries.     

Anti-Biofilm Performance of Three Natural Products against Initial Bacterial Attachment

Marine bacteria contribute significantly towards the fouling consortium, both directly (modern foul release coatings fail to prevent “slime” attachment) and indirectly (biofilms often excrete chemical cues that attract macrofouling settlement). This study assessed the natural product anti-biofilm performance of an extract of the seaweed, Chondrus crispus, and two isolated compounds from terrestrial sources, (+)-usnic acid and juglone, against two marine biofilm forming bacteria, Cobetia marina and Marinobacter hydrocarbonoclasticus. Bioassays were developed using quantitative imaging and fluorescent labelling to test the natural products over a range of concentrations against initial bacterial attachment. All natural products affected bacterial attachment; however, juglone demonstrated the best anti-biofilm performance against both bacterial species at a concentration range between 5–20 ppm. In addition, for the first time, a dose-dependent inhibition (hormetic) response was observed for natural products against marine biofilm forming bacteria.     

Synthesis of dendrimer‐type poly(ethylene glycol) structures from plasma‐functionalized silicone rubber surfaces

PEG oligomers were covalently attached to nonequilibrium, low‐pressure, RF‐plasma‐functionalized silicone medical‐ and industrial‐grade silicon rubber surfaces, in the absence and presence of linear and branched polyglycidol spacer‐chain molecules. All surface‐modification reactions were carried out in a two‐step process involving an initial argon–plasma activation of the surface, followed by “in situ” reaction with dichlorosilane in the absence of the discharge, and the attachment of PEG molecules or the graft polymerization of polyglycidol structures, and the attachment of PEG molecules. The surface of substrates was analyzed after each reaction step, using ESCA, ATR‐FTIR, and AFM. It was found that PEG molecules directly attached to medical‐grade silicone rubber surface as brush‐type structures, and generate stronger antifouling characteristics in comparison to similar structures generated on food‐grade substrates. The presence of additives on the food‐grade silicon rubber surfaces that might be etched and removed during the postplasma washing cycles could contribute to a less efficient attachment of PEG molecules. Surfaces resulting from PEG molecules attached through intermediate, linear, and branched polyglycidol molecules did not reduce bacterial attachment. It is suggested that macromolecular entanglement might be responsible for this behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2324–2337, 2006     

New crosslinked polyurethane elastomers with various physical properties from natural rubber derivatives

New hydroxytelechelic cis‐1,4‐oligoisoprenes exhibiting variable values and distributions of the hydroxyl functionality were successfully prepared. The synthesis reactions involved chemical modifications of carbonyl telechelic cis‐1,4‐polyisoprene, which was obtained by controlled degradation of synthetic or natural rubber. These new oligomers were reacted with toluene diisocyanate to elaborate crosslinked polyurethane elastomers. The thermomechanical properties of the prepared polyurethanes were investigated. The results show a strong relationship between the chemical structures and properties. This work mainly shows the potentiality of making new crosslinking polyurethane materials with controlled and various properties from natural rubber, a renewable resource. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Editorial: Biodegradable Materials

This Special Issue “Biodegradable Materials” features research and review papers concerning recent advances on the development, synthesis, testing and characterisation of biomaterials. These biomaterials, derived from natural and renewable sources, offer a potential alternative to existing non-biodegradable materials with application to the food and biomedical industries amongst many others. In this Special Issue, the work is expanded to include the combined use of fillers that can enhance the properties of biomaterials prepared as films. The future application of these biomaterials could have an impact not only at the economic level, but also for the improvement of the environment.     

低表面能材料上海洋生物附着的研究

考察了不同表面状态的聚四氟乙烯材料和含有机氟、有机硅涂层的防污性能。低表面能材料上的污损生物附着不牢。聚氨酯、醇酸、氯醋乙烯等树脂为基料的涂层防污性差;而涂层中有机硅橡胶的含量比聚四氟乙烯更有利于防止海洋生物的附着。     

A new approach in the development and testing of antifouling paints without organotin derivatives

Environmental concerns have led to a progressive withdrawal of antifouling paints containing organotin derivatives. Resanbio?, a cooperative research program, plans to develop new antifouling paints that are more compatible with living species. In the first stage, we studied specific acrylic polymers with a variable hydrophilic/hydrophobic balance and, in some cases, pendant hydrolyzable functions. To evaluate the ability of these materials for hydrolysis, biocides release, and erosion, test panels with formulated films were prepared and immersed in sea water. An analytical protocol was established to characterize the polymeric material, to reveal chemical reactions that occur during erosion and antifouling action, and to understand the influence of the resin chemical structure on the paint’s antifouling efficiency. The degradation of these binders was revealed by the appearance of a product resulting from the hydrolysis. This product was identified and quantified by GC-MS. The release of cuprous oxide as model molecule, due to its water solubility and biocide activity, was quantified by inductively coupled plasma. The different processes used are explained and illustrated by an example of an efficient, erodable, antifouling paint following 22 months of immersion.     

Rubber‐based acrylate resins: An alternative for tire recycling and carbon neutral thermoset materials design

Rubber is a widely available potential carbon neutral resource, both as native natural rubber state and as vulcanized state in waste tires. Herein, we describe a model synthesis of acrylate telechelic natural rubber (AcTNR) oligomers and the use of such oligomers to prepare novel acrylate resins. AcTNR oligomers are synthesized according to a two steps procedure implying a controlled C = C bond's scission of high‐molecular‐weight natural rubber and a further chain ends functionalization. The molar mass of the resulting AcTNR is found to be 2300 g/mol as determined by ¹H NMR. AcTNR‐based resins are then prepared by mixing AcTNR oligomers with various reactive diluents (RD) such as styrene, 1,4‐butanediol ether, tri(propylene glycol) diacrylate, 1,6‐hexanediol diacrylate, trimethylolpropane triacrylate (AcTNR:RD weight ratio 7:3). These bio‐based resins are afterward cured in the presence of methyl ethyl ketone peroxide as initiator and cobalt octoate as accelerator at 80 °C and postcured at 120 °C. The cured resins offer a wide range of mechanical, thermal, and dynamic‐mechanical performances. This approach could be extended to rubber tire wastes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43548.     

Antifouling activity of novel polyisoprene-based coatings made from photocurable natural rubber derived oligomers

Natural rubber is a renewable resource with a potential as precursor of a very wide range of novel polymers, including polyisoprene-based surfaces with antifouling (AF) activity. In this work, new ionic and non-ionic coatings were prepared by the photocrosslinking reaction of photosensitive cis-1,4-oligoisoprenes, bearing a variable number of ammonium groups. The photochemical crosslinking was achieved using radical (via acrylate groups) or cationic (via epoxy groups) processes. Surface properties of these coatings were studied by static contact angle measurements and AFM imaging. Assessment of bioactivity demonstrated that most of the resulting coatings showed AF potential against fouling organisms: growth inhibition of marine bacteria (Pseudoalteromonas elyakovii, Shewanella putrefaciens, Cobetia marina, Polaribacter irgensii, Vibrio aestuarianus) and fungi (Halosphaeriopsis mediosetigera, Asteromyces cruciatus, Lulworthia uniseptata, Zalerion sp., Monodictys pelagica); decreased adhesion of microalgae (Navicula jeffreyi, Cylindrotheca closterium, Chlorarachnion globosum, Pleurochrysis roscoffensis, Exanthemachrysis gayraliae, Amphora coffeaeformis); inhibition of attachment and/or germination of spores of Ulva intestinalis. The best AF activity was obtained with the ionic surfaces. These new coatings prepared from precursors obtained from natural rubber are in essence active by contact. As the biocidal functions are fixed covalently to the polymer chain, detectable release of biocidal products in the marine ecosystem is prevented so that a valuable environment-friendly alternative for new AF coatings is hereby proposed.     

Effect of high loading of titanium dioxide particles on the morphology,mechanical and thermo-mechanical properties of the natural rubber-based composites

The aim of this work was to prepare and characterize the natural rubber vulcanizates containing different amounts of titanium dioxide particles. At first, a rubber mixture was prepared using a laboratory two-roll mill and then samples were vulcanized by a hydraulic press. The formulation of the rubber mixture and rubber-processing technique were based on our earlier investigations. Samples were obtained with different titanium dioxide loadings of 15, 25, 45, and 85 parts by weight per hundred parts of natural rubber. This research is focused on the determination of the influence of different loadings of titanium oxide particles on the chemical structure, morphology, mechanical and thermo-mechanical properties of the natural rubber-based composites. It was found that vulcanizates with different amounts of TiO₂ particles possess good characteristic in terms of all measured properties. The results of Fourier transform infrared spectroscopy analysis showed that the chemical structure of the obtained natural-based composites was not influenced by titanium dioxide particles. The SEM micrographs showed the uniform dispersion of TiO₂ particles in the natural rubber matrix. The agglomeration of filler was seen at the higher contents of TiO₂ in the matrix. The thermogravimetric analysis showed slightly different thermal stability for the obtained natural rubber composites. The dynamic mechanical thermal analysis showed that the prepared materials have similar glass transition temperatures. However, increase in the content of titanium dioxide in the obtained materials is connected with higher energy loss (higher dissipation of energy) during the mechanical work of material and higher cross-link density of the prepared materials.     

Environmentally Benign Fouling-Resistant Marine Coatings: A Review

The undesirable accumulation of marine organisms on any surfaces immersed in seawater is termed as marine fouling. This natural phenomenon contributes a major economic concern for marine industries, e.g. for ships, vessels, oil, wind-turbine sea-platforms, pipelines, water valves and filters by limiting the performances of the devices and materials. In the last decades, several efforts have been employed in the development of efficient antifouling (AF) coatings by following the recent trend in materials science. The current review presents the research and development made in AF strategies for coatings based on two main approaches, detachment of biofoulants or preventing biofoulants attachment.     

Natural rubber–polyurethane block copolymers: Nonlinear structural variations with NCO/OH ratio

A series of segmented block copolymers was prepared by the chain extension of hydroxyl terminated liquid natural rubber (HTNR) with polyurethane oligomers derived from toluene diisocyanate (TDI) and 1,3‐butane diol at varying NCO/OH ratio. The previously reported two‐step method of synthesis was modified to get improved products. This was done by optimizing the formation of polyurethane oligomers in the first step of the synthesis. All the samples were characterized by solubility testing, DSC, tensile testing, etching studies, and SEM. The data obtained were correlated to the structural features of the block copolymers. It was found that NCO/OH ratio played an important role in determining the structural variations in the block copolymers. POLYM. ENG. SCI. 46:1812–1821, 2006. © 2006 Society of Plastics Engineers     

生物医用硅橡胶表面抗菌性能改造研究进展

硅橡胶材料由于其优越的力学性能及良好的生物相容性,广泛应用于生物医学领域。但使用过程中易引发细菌感染,严重阻碍其临床应用,因此硅橡胶材料的抗菌性能改造成为国内外专家的研究热点。本文综述了近些年关于硅橡胶表面抗菌性能改造的研究成果,介绍了硅橡胶表面的亲水性改造以及不同种类的杀菌剂涂层对材料表面的改性可以有效地提升其抗菌性能。最后对硅橡胶表面抗菌性能改造研究进行展望,指出将亲水化合物与杀菌剂相结合制备出具有抗粘附及杀菌效果的双功能抗菌涂层对硅橡胶表面抗菌性能改造将成为下一步研究重点,同时采用天然可再生资源为原料开发抗菌涂层也将成为重要的研究方向之一。     

The synthesis and cationic polymerization of novel epoxide monomers

The preparation of a novel series of multifunctional silicon-containing epoxide monomers, oligomers, and polymers has been carried out. The hydrosilylation method employed was found to be applicable to the design and synthesis of a wide variety of materials with different chemical and mechanical characteristics, which range from hard and brittle to elastomeric. By tailoring the kinds of and number of epoxide groups that are incorporated into these materials, it is possible to substantially modify their reactivity in photoinitiated cationic polymerization. Those monomers and oligomers containing cycloaliphatic epoxide rings undergo polymerization rates considerably more rapid than conventional epoxides. There are many applications of such photocurable monomers in the field of electronic materials.     

Identification of a Plastid-Localized Bifunctional Nerolidol/Linalool Synthase in Relation to Linalool Biosynthesis in Young Grape Berries

Monoterpenoids are a diverse class of natural products and contribute to the important varietal aroma of certain Vitis vinifera grape cultivars. Among the typical monoterpenoids, linalool exists in almost all grape varieties. A gene coding for a nerolidol/linalool (NES/LINS) synthase was evaluated in the role of linalool biosynthesis in grape berries. Enzyme activity assay of this recombinant protein revealed that it could convert geranyl diphosphate and farnesyl diphosphate into linalool and nerolidol in vitro, respectively, and thus it was named VvRILinNer. However, localization experiment showed that this enzyme was only localized to chloroplasts, which indicates that VvRILinNer functions in the linalool production in vivo. The patterns of gene expression and linalool accumulation were analyzed in the berries of three grape cultivars (“Riesling”, “Cabernet Sauvignon”, “Gewurztraminer”) with significantly different levels of monoterpenoids. The VvRILinNer was considered to be mainly responsible for the synthesis of linalool at the early developmental stage. This finding has provided us with new knowledge to uncover the complex monoterpene biosynthesis in grapes.     

二羟基芦竹碱新型环保防污涂料的研制

介绍了新型防污剂二羟基芦竹碱的应用与合成。以吲哚和二乙醇胺、甲醛为原料,在乙酸催化下合成了二羟基芦竹碱。通过正交试验给出最佳合成条件:反应时间6 h,反应温度25℃,pH为11。用FT-IR1,HNMR对合成的防污剂进行了表征。并将此防污剂应用到防污涂料中,进行杀菌试验,结果表明,此防污涂料具有明显的杀菌性能。     

橡胶籽油基光固化树脂在立体痕迹提取中的应用研究

以橡胶籽油(RSO)为原料,先制得羟基化橡胶籽油,再利用羟基化橡胶籽油与异佛尔酮二异氰酸酯和季戊四醇三丙烯酸酯反应得到橡胶籽油基聚氨酯丙烯酸酯预聚体(RSO-PUA)。将所得预聚体与不同类型稀释单体甲基丙烯酸羟乙酯(HEMA)、1,6-己二醇二丙烯酸酯(HDDA)共混制备可光固化的树脂,研究了其在立体痕迹提取中的应用效果,并与传统的立体痕迹提取材料(硅橡胶、打样膏)的提取效果进行对比。实验结果显示：当稀释剂HEMA的用量为20%、HDDA的用量为30%时,橡胶籽油基光固化树脂的立体痕迹提取性能最优。橡胶籽油基光固化树脂材料提取立体痕迹的操作简便,固化时间快,黏度可控,痕迹反映完整、清晰、锐利, 制作的立体模型具备检验鉴定条件。而硅橡胶和打样膏制作的痕迹模型存在特征缺损、产生气泡、痕迹反映不完整等不足。     

Recycling waste tires: Generation of functional oligomers and description of their use in the synthesis of polyurethane foams

The accumulation of waste tires is a big environmental issue and different approaches have been proposed to eliminate or recycle this material in the end of its life. However, each approach presents drawbacks and the need for a real valorization of the tire components is still of interest. In a previous work by our group, it was demonstrated that an oxidative cleavage of the polyisoprene and polybutadiene chains contained in the tires led to the synthesis of telechelic oligomers with a ketone and an aldehyde at the chains ends. In this work, the process to obtain these carbonyl oligomers has been improved, with a particular concern for the elimination of the maximum amount of carbon black. The carbonyl oligomers can be easily reduced to hydroxyl oligomers and, in order to show the benefit of the recycling process, an application of these hydroxyl oligomers is reported: they have been used as building blocks (polyol precursors) in the preparation of polyurethane (PU) foams. The morphology of the resulting foams was observed by scanning electron microscopy technique: the images showed an almost open‐cell structure and a homogeneous distribution of cell size. Mechanical (tensile and compressive strength) and thermal properties of PU foams synthesized from “recycled” oligomers from waste tires were compared to those of PU foams synthesized from analogue oligomers derived from natural rubber. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41326.     

Advances in layered double hydroxide (LDH)-based elastomer composites

This article reviews the advances in layered double hydroxide (LDH) materials and the synthesis of LDH-based elastomer composites. The potential of tuning the structure of LDH materials for desired properties and applications has attracted both academic and industrial interest in recent years. The modification of LDH materials and the use of such materials in the synthesis of composites with different elastomer matrices have been critically analyzed. Emphasis has been given to the use of Mg-Al LDHs and Zn-Al LDHs with different elastomers. The use of modified LDHs with elastomers substantially improves their mechanical, thermal and optical properties. Even “smart properties” of elastomers, such as reversible thermotropic optical characteristics, have been realized with the use of LDH-based multifunctional additives in rubber formulations. The flame retardance of some elastomer composites has also been enhanced with the use of modified LDHs. The possibility of replacing ZnO with LDH during rubber compounding has also been discussed, which would lead to drastic interventions in the well-established rubber processing technologies. LDH materials have also been reported to be biocompatible. Therefore, among the various possible applications of LDHs in different material development processes, their use in rubber technology offers the potential for environmentally friendly rubber products, even tires. Throughout this article, the structure, synthesis, properties and applications of elastomer/(LDH) composites are discussed, including suitable examples taken from the relevant literature.     

Intermolecular Diels-Alder Cycloadditions of Furfural-Based Chemicals from Renewable Resources: A Focus on the Regio- and Diastereoselectivity in the Reaction with Alkenes

A recent strong trend toward green and sustainable chemistry has promoted the intensive use of renewable carbon sources for the production of polymers, biofuels, chemicals, monomers and other valuable products. The Diels-Alder reaction is of great importance in the chemistry of renewable resources and provides an atom-economic pathway for fine chemical synthesis and for the production of materials. The biobased furans furfural and 5-(hydroxymethyl)furfural, which can be easily obtained from the carbohydrate part of plant biomass, were recognized as “platform chemicals” that will help to replace the existing oil-based refining to biorefining. Diels-Alder cycloaddition of furanic dienes with various dienophiles represents the ideal example of a “green” process characterized by a 100% atom economy and a reasonable E-factor. In this review, we first summarize the literature data on the regio- and diastereoselectivity of intermolecular Diels-Alder reactions of furfural derivatives with alkenes with the aim of establishing the current progress in the efficient production of practically important low-molecular-weight products. The information provided here will be useful and relevant to scientists in many fields, including medical and pharmaceutical research, polymer development and materials science.