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From Forest to Future: Synthesis of Sustainable High‐Molecular‐Weight Polyamides Using, Investigating the AROP of b‐Pinene Lactam
Abstract
Polyamides (PA) are among the most essential and versatile polymers due to their outstanding characteristics, e.g., high chemical resistance and temperature stability. Furthermore, nature‐derived monomers can introduce hard‐to‐synthesize structures into the PAs for unique polymer properties. Pinene, as one of the most abundant terpenes in nature and its presumable stability‐giving bicyclic structure, is therefore highly promising. This work presents simple anionic ring‐opening polymerizations of β‐pinene lactam (AROP) in‐bulk and in solution. PAs with high molecular weights, suitable for further processing, were produced. Their good mechanical, thermal (T d s up to 440°C), and transparent appearance render them promising high‐performance biomaterials. In the following, the suitability of different initiators is discussed. Thereby, it was found that NaH was the most successful for in‐bulk polymerization, with a degree of polymerization (DP) of 322. For solution‐AROP, i PrMgCl·LiCl was successfully used for the first time, achieving DPs up to 163. The obtained PAs were also hot‐pressed, and the dynamic mechanical properties were analyzed.
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Since its introduction in 2004, Knochel's so called Turbo‐Grignard reagents revolutionized the usage of Grignard reagents. Through the simple addition of LiCl to a magnesium alkyl an outstanding increase in reactivity can be achieved. Though the exact composition of the reactive species remained mysterious, the reactive mixture itself is readily used not only in synthesis but also found its way into more distant fields like material science. To unravel this mystery, we combined single‐crystal X‐ray diffraction with in‐solution NMR‐spectroscopy and closed our investigations with quantum chemical calculations. Using such a variety of methods, we have gained insight into and an explanation for the extraordinary reactivity of this extremely convenient reagent by determining the structure of the first bimetallic reactive species [t‐Bu2Mg ⋅ LiCl ⋅ 4 thf] with two tert‐butyl anions at the magnesium center and incorporated lithium chloride.
The growing environmental pollution and the expected depleting of fossil resources have sparked interest in recent years for polymers obtained from monomers originating from renewable sources. Furthermore, nature can provide a variety of building blocks with special structural features (e. g. side groups or stereo‐elements) that cannot be obtained so easily via fossil‐based pathways. In this context, terpenes are widespread natural compounds coming from non‐food crops, present in a large variety of structures, and ready to use as monomers with or without further modifications. The present review aims to provide an overview of how chemists can stereospecifically polymerize terpenes, particularly the acyclic ones like myrcene, ocimene, and farnesene, using different metal catalyst systems in coordination‐insertion polymerization. Attention is also paid to their copolymers, which have recently been disclosed, and to the possible applications of these bio‐based materials in various industrial sectors such as in the field of elastomers. © 2021 The Authors. ChemPlusChem published by Wiley‐VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution Non‐Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Terpene-based polyesteramides (PEAs) are sustainable and have a variety of favorable properties, making them suitable for a wide range of applications and for contribution to a much more sustainable polymer industry. This work focuses on the synthesis of the lactam from β-pinene and its copolymerization with ε-caprolactone. An important step in synthesizing β-pinene lactam is the oxidation of β-pinene to nopinone. To make the established oxidative cleavage more sustainable and efficient, the required amounts of Al2 O3 and KMnO4 are significantly reduced by using H2 SO4 as a catalyst. For the Beckmann rearrangement various catalysts and co-reagents are screened. Among these, the reaction with tosyl chloride is found the most favorable. Subsequently, the chain lengths of the β-pinene-based PEAs are remarkably increased from 6000 g mol-1 to more than 25 100 g mol-1 by fine-tuning reaction time, temperature, and decreasing catalyst and initiator concentrations. Also, different catalysts for polymerization are tested. The resulting material shows melting temperatures of ≈55 °C and decomposition temperatures of 354 °C or higher. Processing via melt pressing or casting turned out to be quite difficult due to the polymer's brittleness. Furthermore, regarding biomedical applications, blends of PEA with polyethylene glycol were successfully prepared, yielding a more hydrophilic material.
Sustainable lactams, which are derived from terpenes, are used for the synthesis of different novel copolymers via ring‐opening polymerization. Different conditions are tested and the incorporation of the different monomers into the polymers is elucidated. This gives access to a variety of new polymer structures and their application range is thus remarkably extended. Sustainable lactams, which are obtained from terpenes, are used for the synthesis of different novel copolymers via ring‐opening polymerization. This gives access to a variety of novel structurally significant copolymers with interesting properties .
The use of renewable feedstock is one of the twelve key principles of sustainable chemistry. Unfortunately, bio-based compounds often suffer from high production cost and low performance. To fully tap the potential of natural compounds it is important to utilize their functionalities that could make them superior compared to fossil-based resources. Here we show the conversion of (+)-3-carene, a by-product of the cellulose industry into ε-lactams from which polyamides. The lactams are selectively prepared in two diastereomeric configurations, leading to semi-crystalline or amorphous, transparent polymers that can compete with the thermal properties of commercial high-performance polyamides. Copolyamides with caprolactam and laurolactam exhibit an increased glass transition and amorphicity compared to the homopolyamides, potentially broadening the scope of standard polyamides. A four-step one-vessel monomer synthesis, applying chemo-enzymatic catalysis for the initial oxidation step, is established. The great potential of the polyamides is outlined.
ε-Poly-lysine (ε-PL) is an uncommon cationic, naturally-occurring homopolymer produced by the fermentation process. Due to its significant antimicrobial activity and nontoxicity to humans, ε-PL is now industrially produced as an additive, e.g. for food and cosmetics. However, biosynthetic route can only make polymers with a molecular weight of about 3 kDa. Here, we report a new chemical strategy based on ring-opening polymerization (ROP) to obtain ε-PL from lysine. The 2,5-Dimethylpyrrole protected α-amino-ε-caprolactam monomer was prepared through cyclization of lysine followed by protection. ROP of this monomer, followed by the removal of the protecting group, 2,5-dimethylpyrrole, ultimately yielded ε-PL with varying molecular weights. The structure of this chemosynthetic ε-PL has been fully characterized by 1H NMR, 13C NMR, and MALDI-TOF MS analyses. This chemosynthetic ε-PL exhibited a similar pKa value and low cytotoxicity as the biosynthetic analogue. Using this new chemical strategy, involving ROP without the need of phosgene, may enable a more cost effective production of ε-PL in larger-scale, facilitating the design of more advanced biomaterials.
Over the past decade, the effectiveness of i-PrMgCl•LiCl has been constantly highlighted by a number of research groups. Its enhanced nucleophilicity brings prosperity to highly functionalized Grignard reagents, other useful bimetallic (alkali-metal) agents and nucleophilic alkylation products under mild reaction conditions. In this feature article, a comprehensive, systematical and in-depth overview of i-PrMgCl•LiCl is provided in a multidisciplinary idea. It involves the structural and kinetic perspectives of i-PrMgCl•LiCl as well as its unique reactivity and selectivity, with knowledge of the former helping to rationalize the trends of the later.
Foods and pharmaceuticals materials are exposed to various environmental conditions during processing and while in storage; therefore, stability and quality are key attributes of concern. The properties of foods and pharmaceutical materials that define their quality are affected by conditions such as temperature, humidity and time. Glass transition is considered a key material property to understand how these external conditions affect the stability and quality of foods and pharmaceuticals. Thus, investigating the thermo-mechanical properties of these materials as well as characterizing the glass transition temperature have a great interest not only in the food industry, but also extend to the pharmaceutical and polymer industries. The aim of this study was to design and test a new disposable powder holder that allows the use of a dynamic mechanical analysis (DMA) instrument to test and characterize loose powder samples. The disposable aluminum powder holder was designed and constructed to be used in the single cantilever configuration on a TA Instruments RSA III DMA. Three different powder samples – Felodipine, polyethylene-oxide (MW 900 kDa) and HPMC (E4M) – were used for validation. The use of this powder holder allows the detection of different thermal changes of powder samples without compacting and when large sample size is necessary for detection and/or interpretation.
The utilization of plant oil renewable resources as raw materials for monomers and polymers is discussed and reviewed. In an age of increasing oil prices, global warming and other environmental problems (e.g. waste) the change from fossil feedstock to renewable resources can considerably contribute to a sustainable development in the future. Especially plant derived fats and oils bear a large potential for the substitution of currently used petrochemicals, since monomers, fine chemicals and polymers can be derived from these resources in a straightforward fashion. The synthesis of monomers as well as polymers from plant fats and oils has already found some industrial application and recent developments in this field offer promising new opportunities, as is shown within this contribution. (138 references.)
Ring opening polymerization (ROP) of lactams is a highly efficient and versatile method to synthesize polyamides. Within the last ten years, significant advances in polymerization methodology and monomer diversity are ushering in a new era of polyamide chemistry. We begin with a discussion of polymerization techniques including the most widely used anionic ring opening polymerization (AROP), and less prevalent cationic ROP and enzyme-catalyzed ROP. Next, we describe new monomers being explored for ROP with increased functionality and stereochemistry. We emphasize the relationships between composition, structure, and properties, and how chemists can control composition and structure to dictate a desired property or performance. Finally, we discuss biomedical applications of the synthesized polyamides, specifically as biomaterials and pharmaceuticals, with examples to include as antimicrobial agents, cell adhesion substrates, and drug delivery scaffolds.
In this work; the synthesis of the terpene‐based limonene lactam prepared from limonene epoxide is presented; as well as its subsequent ring‐opening polymerization (ROP) to novel polyamides. Sustainable; biobased materials are gaining interest as replacement of conventional; petroleum‐based materials; and even more important; as materials with enhanced performance for new applications. Terpenes – structurally advanced biobased compounds – are therefore of great interest. In this research a promising biobased monomer for preparing sustainable polyamides via ROP could be synthesized by transforming limonene to limonene lactam. Limonene lactam posseses an isopropylene and a methyl side group; thus stereocenters posing special challenges and requirements for their synthesis; analysis and polymerization. However; these difficult‐to‐synthesize structural elements generate; if sucessfully incorporated into the polymer; novel polymers with unique properties;, e.g., functionalizability. In this work; a successful; sustainable monomer synthesis is established; and simplification to industrial needs through improvements of the synthesis route regarding purification and upscaling is achieved. For the sterically demanding in‐bulk ROP to limonene‐based polyamides; various initiators and conditions were tested. Polyamides with more than 100 monomer units were sucessfully synthesized and confirmed via NMR and GPC. DSC and TGA were used to analyze its thermal properties. In summary; a sustainable limonene lactam synthesis is established; and promising polyamides with an intact double bond and interesting thermal properties are achieved. This article is protected by copyright. All rights reserved
Aliphatic polyamides, or nylons, are typically highly crystalline and thermally robust polymers used in high-performance applications. Nylon 6, a high-ceiling-temperature (HCT) polyamide from ε-caprolactam, lacks expedient chemical recyclability, while low-ceiling temperature (LCT) nylon 4 from pyrrolidone exhibits complete chemical recyclability, but it is thermally unstable and not melt-processable. Here, we introduce a hybrid nylon, nylon 4/6, based on a bicyclic lactam composed of both HCT ε-caprolactam and LCT pyrrolidone motifs in a hybridized offspring structure. Hybrid nylon 4/6 overcomes trade-offs in (de)polymerizability and performance properties of the parent nylons, exhibiting both excellent polymerization and facile depolymerization characteristics. This stereoregular polyamide forms nanocrystalline domains, allowing optical clarity and high thermal stability, however, without displaying a melting transition before decomposition. Of a series of statistical copolymers comprising nylon 4/6 and nylon 4, a 50/50 copolymer achieves the greatest synergy in both reactivity and polymer properties of each homopolymer, offering an amorphous nylon with favorable properties, including optical clarity, a high glass transition temperature, melt processability, and full chemical recyclability.
Bio-based compounds with unique chemical functionality can be obtained through selective transformations of plant and other non-fossil, biogenic feedstocks for the development of new polymers to displace those produced from fossil carbon feedstocks. Although substantial efforts have been invested to produce bio-based polymers that are chemically identical to and directly replace those from petroleum, a long-pursued goal is to synthesize new, sustainable, bio-based polymers that either functionally replace or exhibit performance advantages relative to incumbent polymers. Owing to anthropogenic climate change and the environmental consequences of global plastics pollution, the need to realize a bio-based materials economy at scale is critical. To that end, in this Review we describe the concept of performance-advantaged, bio-based polymers (PBPs), highlighting examples wherein superior performance is facilitated by the inherent chemical functionality of bio-based feedstocks. We focus on PBPs with C–O and C–N inter-unit chemical bonds, as these are often readily accessible from bio-based feedstocks, which are heteroatom-rich relative to petroleum-derived feedstocks. Finally, we outline guiding principles and challenges to aid progress in the development of PBPs. Bio-based polymers that exhibit superior performance relative to petroleum-based incumbents can encourage industry adoption and offset fossil carbon use. This Review introduces performance-advantaged, bio-based polymers and highlights examples wherein superior performance is facilitated by the inherent chemical functionality of bio-based feedstocks.
There are different types of biomaterials, including metals and alloys, ceramics, polymers, and composite biomaterials, which are used in various medical fields. Among these, polymer biomaterials have gained a great attention in biomedicine due to their unique properties, including flexibility, resistance to biochemical attack, good biocompatibility, lightweight, and availability in a wide variety of compositions with adequate physical and mechanical properties. One of the main advantages of biopolymers compared to ceramics
and metals is their ease of manufacturing various shapes such as latex, films, fibers, and sheet. On the other hand, stress-shielding and osteoporosis effects are serious problems associated with metal-based implants on underlying bone grafts as a result of the rigidity of the reconstruction system.
Our dependence on fossil-fuel based raw materials and alarming plastics accumulation in the environment has inspired many scientists to design and implement more sustainable approaches for polymer synthesis. The identification and assessment of new and renewable biobased monomers has become a major topic of interest en route to a circular economy. In this respect, terpenes and terpenoid scaffolds have attracted much attention due to their ubiquitous nature and high functionality. This minireview uncovers recent advancements in the synthesis of terpene-based polymers, and specifically discusses the formation of terpene-derived polycarbonates, polyesters, polyurethanes and polyamides. The potential of these polymers in post-synthetic curing and modifications is also highlighted to illustrate the opportunities that exist to develop new polymer formulations beyond bench scale.
In addition to their established usage in textiles, commodities, and automotives, classical polyamides (nylons) are recently becoming increasingly interesting for applications in (bio)medicine. This fact relies on many prosperous properties of these polymers, which are toughness, resistance, biocompatibility, low immunogenicity, tunable biodegradability, and their similarity to natural peptides (amide bonds). Some nylon‐based medical products do already exist for wound treatment applications, implants, and biomolecule‐interacting membranes, but the systematic use of these polymers for tissue engineering is—although desired—still to be accomplished. Inspired by this, the suitability of nylon 6 and of a related biobased and more hydrophobic terpene‐derived polyamide as surfaces for the controlled interaction with HaCat cells (human keratinocytes) are investigated herein with regard to possible applications for regenerative skin replacement. The nylons are applied as neat polymers and as hydrophilized blends/composites with polyethylene glycol and confirm their excellent suitability as biomaterials. Polyamides (nylons), which have been used for textiles, commodities, and automotives for decades, are also becoming increasingly interesting for medical applications. Herein, novel blends consisting of a polyamide (nylon 6 or a biobased, terpene‐based polyamide) and polyethylene glycol (and a corresponding copolymer), as well as their interactions with human keratinocytes, are described. This approach is very promising with regard to skin tissue engineering.
The synthesis and polymerization of two β‐lactams and two ε‐lactams derived from the terpenes α‐pinene and (+)‐3‐carene are reported. The new biopolymers can be considered as polyamide 2 (PA2) and polyamide 6 (PA6)‐types with aliphatic stereoregular side chains, which lead to remarkable new properties. The macromolecules are investigated by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and infrared (IR). The (+)‐3‐carene‐derived PA6‐type is of particular interest, since it reaches a molecular weight of over 30 kDa, which is the highest value for lactam‐based polyamides derived from terpenes reported to date. Additionally, a glass transition temperature (Tg) of 120 °C is observed, surpassing the glass transition temperature of PA6 by 60 °C. The absence of a melting point (Tm) indicates high amorphicity, another novelty for terpene‐based polyamides, which might give transparent bio‐polyamides access to new fields of application.
Pinenes ‐ a group of monoterpenes containing a double bond ‐ are very suitable renewable building blocks for a variety of sustainable polymers and materials. Their abundance from mainly non‐edible parts of plants as well as the feasibility to isolate them render these compounds unique amongst the variety of biomass that is utilizable for novel materials. Accordingly, their use for the synthesis of biobased polymers has been investigated intensively, and strong progress has been made with this especially within the past 2‐3 years. Direct cationic or radical polymerization via the double bonds as well as polymerization upon their further functionalization can afford a variety of sustainable polymers suitable for many applications, which is summarized in this article.
Due to the longevity of the cationic active centers, cationic ring‐opening photopolymerization can continue after illumination ceases. In addition, substantial reactivity enhancement for epoxides is realized through copolymerization with oxetanes. Here, the separate reactions of epoxide and oxetane moieties were resolved during illumination and subsequent dark cure via real‐time Raman spectroscopy. Using oxetane additives, reactivity and conversion of 3,4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexane carboxylate (EEC) were improved during illumination and subsequent dark cure through modulation of the initial formulation viscosity and selection of the oxetane secondary functional groups. The largest enhancement in reactivity occurred with secondary groups comprising either aliphatic chains with their flexibility or hydroxyls with their chain‐transfer capacity. In contrast, oxetanes containing UV‐absorbing phenyl rings reduced the initiation efficiency, and difunctional oxetanes suppressed overall conversion through additional crosslinking. Although bulk conversion was directly related to initial formulation viscosity, the impact of the oxetane secondary functional groups was greater. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018
A sustainable lactam, which is derived from the renewable terpene β-pinene, is converted to polyamides via a convenient anionic polymerization, which can be easily handled without the use of a...
Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymerizations and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.
Polyamides are very important polymers that find applications from commodities up to the automotive and biomedical sectors, and their impact is continuously growing. The synthesis of structurally significant, chiral, and sustainable polyamides is described via a new, convenient, and solvent-free anionic polymerization of a biobased ε-lactam, which is obtained from the renewable terpenoid ketone l-menthone in a one-step synthesis. These polyamides are shown to have outstanding structural and thermal properties, which are thus introduced via the structure and chirality of the natural lactam monomer and which are discussed and compared with those of petroleum-based, established, and commercial polyamide Nylon-6. X-ray data reveal a remarkable degree of crystallinity in these green polymers and emphasize the impact of their structural features on the resulting properties.
The ring-opening polymerization (ROP) of lactams is extensively reviewed, covering all aspects related to their polymerizability, in terms of both thermodynamic feasibility and kinetic likeliness, with greater attention to the many different aspects of the anionic polymerization, also in terms of its industrial applications. Other polymerization mechanisms (e.g., cationic) or routes (e.g., enzymatic) are synthetically introduced and updated. Specific lactams (ε-caprolactam (CL), ω-laurolactam, 2-pyrrolidone, and C-substituted β-lactams) and their anionic polymerization are described in detail, with a mention of the living polymerization of the latter family of lactams. Anionic copolymers of the most relevant lactams are listed, with a description of the synthetic routes adopted for each pair.
Dwindling fossil resources, surging energy demand and global warming stimulate growing demand for renewable polymer products with low carbon footprint. Going well beyond the limited scope of natural polymers, biomass conversion in biorefineries and chemical carbon dioxide fixation are teamed up with highly effective tailoring, processing and recycling of polymers. “Green monomers” from biorefineries, and “renewable oil”, gained from plastics' and bio wastes, render synthetic polymers renewable without impairing their property profiles and recycling. In context of biofuel production, limitations of the green economy concepts are clearly visible. Dreams and reality of “green polymers” are highlighted. Regardless of their new greenish touch, highly versatile and cost-effective polymers play an essential role in sustainable development.
The field of sustainable polymers is growing and evolving at unprecedented rates. Researchers are increasingly concerned with the feedstock origins and the degradation behavior of, especially, large-scale commodity packaging plastics. A perspective is offered here for the design of sustainable polymers, specifically addressing opportunities for monomer development and polymer degradation. Key concepts include: water degradability instead of biodegradability; incorporation of novel main-chain functionality, such as acetals; utilization of lignin-based aromatics; and direct polymerization of biogenic C1 feedstocks.
Laurolactam (LL) is polymerized in the bulk using strongly basic N-heterocyclic carbenes (NHCs) as initiators at temperatures of 180–200 °C to prepare the corresponding polyamide (PA 12). In-situ rheology of the polymerization progress reveals that an anionic mechanism is active, which is supported by the strong dependence of initiator activity on the basicity of the NHCs. GPC data and kinetic investigations show the process to be moderately controlled and fast, allowing high or quantitative yields in short polymerization times. Fifteen different NHC–CO2–adducts and NHC–metal complexes were used as thermally labile but room temperature stable NHC-precursors. Depending on the ring size and N-substituent, some of these protected NHCs allow forming a mixture of monomer and NHC-precursor that is suitable for long-term storage and readily polymerizable by simple heating. All polymerizations are executed without activator or other additives and thus represent a true one-component system for the production of PA 12. Finally, LL is copolymerized with ε-caprolactam (ε-CLA). It is found that a copolymer with a considerable gradient is formed, with ε-CLA being incorporated preferentially at the onset of the polymerization.
Natural molecular biomass plays an important role in the field of renewable polymers, as they can be directly used or derivatized as monomers for controlled polymerization, in a way similar to many petroleum-derived monomers. We deliver this perspective primarily based on a monomer approach. Biomass-derived monomers are separated into four major categories according to their natural resource origins: (1) oxygen-rich monomers including carboxylic acids (lactic acid, succinic acid, itaconic acid, and levulinic acid) and furan; (2) hydrocarbon-rich monomers including vegetable oils, fatty acids, terpenes, terpenoids and resin acids; (3) hydrocarbon monomers (bio-olefins); and (4) non-hydrocarbon monomers (carbon dioxide). A variety of emerging synthetic tools (controlled polymerization and click chemistry) are particularly summarized. An overview on future opportunities and challenges, which are critical to promote biorefinery in the production of renewable chemicals and polymers, is given.
Green Chemistry is a relatively new emerging field that strives to work at the molecular level to achieve sustainability. The field has received widespread interest in the past decade due to its ability to harness chemical innovation to meet environmental and economic goals simultaneously. Green Chemistry has a framework of a cohesive set of Twelve Principles, which have been systematically surveyed in this critical review. This article covers the concepts of design and the scientific philosophy of Green Chemistry with a set of illustrative examples. Future trends in Green Chemistry are discussed with the challenge of using the Principles as a cohesive design system (93 references).
Recent development in the field of the ring-opening polymerization of lactams is reviewed from the viewpoint of the living polymerization. The living anionic polymerization of several lactams has been attained by skillful selection of the monomer structure and the polymerization condition. The chemical modification of the acyllactam-type growing chain ends in the resulting monodisperse living polyamides is also described to be useful for the molecular design of various types of the well-defined and polyamide-composed polymeric materials.
Renewable ABA triblock copolymers were prepared by sequential polymerization of the plant-based monomers menthide and α-methylene-γ-butyrolactone (MBL or tulipalin A). Ring-opening transesterification polymerization of menthide using diethylene glycol as an initiator gave α,ω-dihydroxy poly(menthide) (HO-PM-OH), which was converted to α,ω-dibromo end-functionalized poly(menthide) (Br-PM-Br) by esterification with excess 2-bromoisobutyryl bromide. The resulting 100 kg mol(-1) Br-PM-Br macroinitiator was used for the atom transfer radical polymerization of MBL. Four poly(α-methylene-γ-butyrolactone)-b-poly(menthide)-b-poly(α-methylene-γ-butyrolactone) (PMBL-PM-PMBL) triblock copolymers were prepared containing 6-20 wt % PMBL, as determined by NMR spectroscopy. Small-angle X-ray scattering, differential scanning calorimetry, and atomic force microscopy experiments supported microphase separation in the four samples. The mechanical behavior of the triblocks was investigated by tensile and elastic recovery experiments. The tensile properties at both ambient and elevated temperature show that these materials are useful candidates for high-performance and renewable thermoplastic elastomer materials.
Es wird die Umsetzung von Methylnopinol und Pinenhydrat mit Chlorwasserstoff in Diäthyläther untersucht und mit der Anlagerung von HCl an α- und β-Pinen in Dimethyläther verglichen — Mit der stöchiometrischen Menge HCl gibt Methylnopinol Limonenhydrochlorid und tertiäres Chlorpinan. dessen Konstitution durch Bildung von α-Pinen mit alkoholischer Lauge erwiesen wird; es isomerisiert sich, wobei Fenchylchlorid, aber auch etwas Bornylchlorid entstehen. Pinenhydrat spaltet sofort Wasser ab; das Reaktionsprodukt enthält α-Pinen, wohl auch etwas β-Pinen, Limonenhydrochlorid, Fenchylchlorid und Bornylchlorid. Aus α-Pinen, mit der stöchiometrischen Menge HCl in Dimethyläther, entstehen dieselben Produkte wie aus Pinenhydrat, nur überwiegt hier das Bornylchlorid etwas. β-Pinen gibt dagegen neben Limonenhydrochlorid fast nur Bornylchlorid. — Die sterischen Verhältnisse bei den Umlagerungen des Pinangerüsts werden im Zusammenhang mit den Konfigurationen von Methylnopinol und Pinenhydrat erörtert.
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