Conjugated polymers with regularly spaced m‐phenylene units and post‐polymerization modification to yield stimuli‐responsive materials

Two π‐conjugated polymers featuring main‐chain m‐phenylene linkers as well as iodo substituents were initially prepared. The presence of the iodo functionality allowed for the preparation of six additional polymers from the initial two iodo‐substituted polymers via facile post‐polymerization modification using Sonogashira‐type coupling chemistry. The post‐polymerization modification led to crosslinking, to the incorporation of a pyridyl‐bearing functionality for potential use as a ligand for transition metals or to the introduction of a ferrocenyl substituent as a possible redox‐active unit. The m‐phenylene units were incorporated into the polymer main‐chain structure in order to periodically disrupt conjugation, thereby allowing for more uniformity in the effective conjugation length and thus in absorption and emission profiles. The thermal stability and photophysical properties of all eight polymers, as well as the stimuli‐responsiveness of relevant materials to nitroaromatics and metal ions, are reported. © 2015 Society of Chemical Industry     

Double dynamic self‐healing polymers: supramolecular and covalent dynamic polymers based on the bis‐iminocarbohydrazide motif

Self‐healing polymers are a class of functional polymers that, by the virtue of the presence of certain dynamic chemical linkages, may undergo self‐repair at a mechanically cut surface. Herein we report the synthesis of a self‐healing polymer giving access to double dynamicity within the polymer network by making use simultaneously of reversible covalent bonds and dynamic non‐covalent hydrogen bonding interactions. These features are provided, respectively, by doubly dynamic cassettes comprising chemically reversible imine linkages and multiply hydrogen‐bonded urea groups, connected by a siloxane‐based backbone that imparts softness to the material. Such a system can be envisaged to give access to a broad spectrum of functional materials, which can be tuned by convenient modulation of the structural motifs of the polymer. © 2013 Society of Chemical Industry     

Camelina oil‐ and linseed oil‐based polymers with bisphosphonate crosslinks

Natural oils are the attractive biobased alternatives for petroleum derived chemicals in the production of polymers. A series of new biodegradable polymers based on epoxidized camelina oil was synthesized and investigated. The thermal, mechanical, swelling properties, hydrolysis, biodegradation, and bioresistance of the camelina oil‐based polymers with bisphosphonate crosslinks were studied and compared with those of the analogous polymers based on epoxidized linseed oil. The dependence of the polymer properties on the density of crosslinks was observed. The obtained results showed that the properties of the camelina oil‐based polymers are comparable with those of the linseed oil‐based polymers and that camelina oil is a promising starting material for the synthesis of polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40683.     

Hydroxyethyl chitosan‐g‐poly(acrylic acid‐co‐sodium acrylate) superabsorbent polymers

A novel hydroxyethyl chitosan‐g‐poly(acrylic acid‐co‐Sodium Acrylate) (HECTS‐g‐(PAA‐co‐PSA)) superabsorbent polymer was prepared through graft copolymerization of acrylic acid and sodium acrylate onto the chain of hydroxyethyl chitosan. The structure of the polymer was characterized by FTIR. By studying the water absorption of the polymer synthesized under different conditions, the optimal conditions for synthesizing the polymer with the highest swelling ratio was defined. This superabsorbent polymer was further treated by the solvent precipitation method and by the freeze‐drying method. We found that the water absorption rate of the treated polymer was greatly increased and the microstructure of the treated polymer was changed from small pores to loose macro pores. The swelling processes of the polymers before and after modification fit first‐order dynamic processes. The amount of the residual acrylic acid was greatly decreased after treatments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Functional water‐soluble polymers: polymer–metal ion removal and biocide properties

Water‐soluble polymers have attracted much interest due to their potential applications in environmental protection engineering to remove harmful pollutants and in biomedicine in the areas of tissue engineering, within‐body implants or other medical devices, artificial organ prostheses, ophthalmology, dentistry, bone repair, and so on. In this review, particular emphasis is given to the ability of water‐soluble polymers with amine, amide, carboxylic acid, hydroxyl and sulfonic acid functional groups to remove metal ions by means of the liquid‐phase polymer‐based retention (LPR) technique that combines the use of water‐soluble polymers and ultrafiltration membranes. The second part is dedicated to showing the potential application of functional water‐soluble polymers and their polymer–metal complexes as biocides for various bacteria. These polymers and polymer–metal complexes show an efficient bactericide activity, especially to Gram‐negative bacteria, Staphylococcus aureus reaching concentrations lower than 4 µg mL^?1. This activity depends on polymer size, type of metal ion, contact time and concentration of polymer and metal ion. The discussion reveals that in the case of the LPR process the efficiency of metal ion removal depends strongly on the type of polymer functional group and the feed pH value. In general, two mechanisms of ion entrapment are suggested: complex formation and electrostatic interaction. In the case of the medical use of water‐soluble polymers and their complexes with metal ions, the review documents the unique bactericide properties of the investigated species. The polymer‐metal ion complexes show a reduced genotoxic activity compared with free metal ions. Copyright © 2009 Society of Chemical Industry     

Stereocomplexed polylactides (Neo‐PLA) as high‐performance bio‐based polymers: their formation,properties, and application

Polymeric materials prepared from renewable natural resources are now being accepted as “bio‐based polymers”, because they are superior to the conventional petroleum‐based polymers in reducing the emission of carbon dioxide. Among them, poly(L ‐lactide) (PLLA) prepared by fermentation and polymerization is paid an immediate attention. Although PLLA exhibits a broad range of physico‐chemical properties, its thermal and mechanical properties are somewhat poorer for use as ordinary structural materials. For improving these inferior properties, a stereocomplex form consisting of PLLA and its enantiomer poly(D ‐lactide) (PDLA) has high potential because of showing high melting nature (230 °C). It can be formed by simple polymer blend of PLLA and PDLA or more easily with stereoblock polylactides (sb‐PLA) which are PLLA/PDLA block copolymers. These novel PLA polymers, named “Neo‐PLA”, can provide a wide range of properties that have never be attained with single PLLA. Neo‐PLA retains sustainability or bio‐based nature, because both monomers L ‐ and D ‐lactic acids are manufactured from starch by fermentation. Copyright © 2006 Society of Chemical Industry     

Side‐chain liquid‐crystalline polymers with a limonene‐co‐methyl methacrylate main chain: Synthesis and characterization of polymers with phenyl benzoate mesogenic groups

A new series of liquid‐crystalline polymers with a polymer backbone of limonene‐co‐methyl methacrylate were synthesized and characterized, and the spacer length was taken to be nine methylene units. The chemical structures of the obtained olefinic compound and polymers were confirmed with elemental analysis and proton nuclear magnetic resonance spectroscopy. The thermal behavior and liquid crystallinity of the polymers were characterized with differential scanning calorimetry and polarized optical microscopy. The polymers exhibited thermotropic liquid‐crystalline behavior and displayed a glass‐transition temperature at 48°C. The appearance of the characteristic schlieren texture confirmed the presence of a nematic phase, which was observed under polarized optical microscopy. These liquid‐crystalline polymers exhibited optical activity. A comparison was also made with polyacrylates and polymethacrylate‐based materials. This revealed that the nature of the polymer backbone had a major effect on the liquid‐crystalline properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4595–4600, 2006     

Modifying and managing the surface properties of polymers

An ongoing challenge in polymer science is the preparation of materials with bespoke surface properties which differ from that of the bulk, for example hydrophobicity, wettability, chemical resistance, adhesion or biocompatibility. We highlight here recent efforts in the design, development and application of (multi)end‐functionalized polymers as additives for the efficient modification of polymer surface properties. Aryl‐ether moieties bearing up to eight functional groups have been used as initiators for the controlled polymerization of both styrene and methyl methacrylate by atom transfer radical polymerization (ATRP) and of lactide by ring opening polymerization (ROP). The resulting polymers have been used as additives to modify the surfaces of the corresponding bulk polymers. Fluorinated polymer surfaces are particularly appealing in terms of their liquid repellence, chemical inertness and low coefficient of friction. When an additive consisting of a low molecular weight polystyrene chain, end‐capped with four C₈F₁₇ groups, is present in a matrix of polystyrene at levels as low as 0.1%, near polytetrafluoroethylene‐like surface properties result. Copyright © 2007 Society of Chemical Industry     

Self‐healing polymeric materials towards non‐structural recovery of functional properties

Self‐healing of polymers and polymer composites initially represented a process capable of autonomic restoration of mechanical strength upon cracking of the materials, but it is moving into the area of restoration of functionality. This mini‐review is focused on recent efforts to develop functional polymers with built‐in stimuli‐responsive ability to heal for recovery of their specific physical or chemical properties. Molecular design and synthesis, compounding and assembly of organic and inorganic species, inherent reversibility, etc., are summarized. It is hoped that much more interest will be aroused in this emerging and promising frontier topic. © 2014 Society of Chemical Industry     

Fatty acid‐based comonomers as styrene replacements in soybean and castor oil‐based thermosetting polymers

In this study, a fatty acid‐based comonomer is employed as a styrene replacement for the production of triglyceride‐based thermosetting resins. Styrene is a hazardous pollutant and a volatile organic compound. Given their low volatility, fatty acid monomers, such as methacrylated lauric acid (MLA), are attractive alternatives in reducing or eliminating styrene usage. Different triglyceride‐derived cross‐linkers resins were produced for this purpose: acrylated epoxidized soybean oil (AESO), maleinated AESO (MAESO), maleinated soybean oil monoglyceride (SOMG/MA) and maleinated castor oil monoglyceride (COMG/MA). The mechanical properties of the bio‐based polymers and the viscosities of bio‐based resins were analyzed. The viscosities of the resins using MLA were higher than that of resins with styrene. Decreasing the content of MLA increased the glass transition temperature (T_g). In fact, the T_g of bio‐based resin/MLA polymers were on the order of 60°C, which was significantly lower than the bio‐based resin/styrene polymers. Ternary blends of SOMG/MA and COMG/MA with MLA and styrene improved the mechanical properties and reduced the resin viscosity to acceptable values. Lastly, butyrated kraft lignin was incorporated into the bio‐based resins, ultimately leading to improved mechanical properties of this thermoset but with unacceptable increases in viscosity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Computer simulation and synthesis of stimuli‐responsive polymer by sol‐gel for selective recognition of (4‐chloro‐2‐methylphenoxy)acetic acid

A novel photoresponsive functional monomer bearing a siloxane polymerizable group and azobenzene moieties was synthesized, and then photoresponsive molecularly imprinted sol‐gel polymers were successfully fabricated from the synthesized functional monomer, using (4‐chloro‐2‐methylphenoxy)acetic acid (MCPA) as a molecular template. The photoisomerization properties of the functional monomer are retained after incorporation into the rigid three‐dimensional crosslinked polymer matrix. The template is then removed from the resulting polymer to generate pores, which are complementary to the template in shape, size and functionality. The substrate affinity of the molecularly imprinted polymer (MIP) receptor sites is photoswitchable. This can be attributed to the photoisomerization of azobenzene chromophores within the MIP receptors, resulting in alteration of their geometry and the spatial arrangement of their binding functionalities. The binding affinity of the imprinted recognition sites was switchable by alternate irradiation with UV and visible light, suggesting that azobenzene groups located inside the binding sites could be used as chemical sensors and the trans–cis isomerization could regulate the affinity for MCPA. To study the hydrogen bond interactions between template molecules and functional monomer, computational molecular modeling was employed. The data indicate that the design of the MIP is rational. Copyright © 2012 Society of Chemical Industry     

Side‐chain functionalized supramolecular polymers

Over the past two decades, the field of supramolecular polymer chemistry has developed from a curiosity to a mature area of polymer science. Among the most promising subjects in this large field are noncovalently functionalized side‐chain polymers that have been investigated extensively as a result of their modular character and ease of synthesis. Side‐chain functionalized polymers have the potential for a profound impact on complex materials. For example, for side‐chain functionalized polymers based on a single noncovalent interaction, materials for a variety of applications ranging from liquid crystalline and electro‐optical materials to drug delivery systems have been reported. Furthermore, materials based on this novel methodology may overcome several shortcomings of current covalent multifunctionalization strategies such as highly complex materials that are extremely difficult or impossible to fabricate with current methods. In this review, basic design requirements, advantages and potential applications are presented. Copyright © 2006 Society of Chemical Industry     

The colloidal properties of alkaline‐soluble waterborne polymers

Waterborne polymer dispersions are widely used in coatings and graphic arts markets as environmentally friendly and more sustainable alternatives to solvent borne binders. Traditionally, waterborne (meth)acrylic dispersions are prepared by emulsion polymerization using low molar mass surfactants as a key ingredient to control particle size. However, these surfactants can have a negative influence on the performance of coatings such as reduced water resistance and adhesion. To mitigate the negative effects of surfactants, polymer latexes have been developed that employ alkaline‐soluble polymers as the sole stabilizer for a subsequent emulsion polymerization step. In this way surfactant‐free polymer dispersions are obtained. Despite the high commercial impact and relevance of this technology, fundamental studies regarding the physicochemical properties of the alkaline‐soluble polymers are lacking. In this article, the synthesis and colloidal properties of alkaline‐soluble waterborne methacrylic copolymers are reported. The dissolution behavior and colloidal properties of these alkaline‐soluble polymers were studied as function of molar mass, acid content, and pH. The dissolving polymer particles were characterized using static and dynamic light scattering, static and dynamic surface tension measurements, and cryogenic‐transmission electron microscopy analysis. It is concluded that the dissolution mechanism of alkaline‐soluble polymers follows a gradual process. As the pH increases deprotonation of the carboxylic acid groups swells the particle enhancing the further swelling with water. At a certain amount of base, the particles disintegrate into small polymer aggregates while the most water‐soluble polymer chains are dissolved in the water phase. An important learning is that part of the alkaline‐soluble polymer resides in very small particles (<5 nm). The formation of these polymer particles below 5 nm was not reported previously and offers a new insight into the dissolution mechanism of alkaline soluble polymers. The most important parameter steering this process is the acid value of the polymer, while the molar mass plays a modest role. The understanding gained in this study can be used to further advance alkaline‐soluble polymers as stabilizer in surfactant‐free emulsion polymerization technology, improving the performance of a wide range of industrially relevant coatings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46168.     

Miscibility of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) with high molecular weight poly(lactic acid) blends determined by thermal analysis

An important strategy used in the polymer industry in recent years is blending two bio‐based polymers to attain desirable properties similar to traditional thermoplastics, thus increasing the application potential for bio‐based and bio‐degradable polymers. Miscibility of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) with poly(L ‐lactic acid) (PLA) were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Three different grades of commercially available PLAs and one type of PHBV were blended in different ratios of 50/50, 60/40, 70/30, and 80/20 (PHBV/PLA) using a micro‐compounder at 175°C. The DSC and TGA analysis showed the blends were immiscible due to different stereo configuration of PLA polymer and two distinct melting temperatures. However, some compatibility between PHBV and PLA polymers was observed due to decreases in PLA's glass transition temperatures. Additionally, the blends do not show clear separation by SEM analysis, as observed in the thermal analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Nanofabrication with metallopolymers ‐ recent developments and future perspectives

Synthetic polymers containing metals and metal centers have experienced rapid growth in the last two decades. Metal‐containing polymers have an unprecedented role to play in modern high‐tech applications including nanomanufacturing, sensing, separation and catalysis. Advancement in synthetic strategies for macromolecules has enabled the synthesis of novel, exotic and use‐inspired metallopolymers. Using state‐of‐the‐art design strategies, it is now possible to perform targeted synthesis of macromolecules with varied complexity that contain a range of metal centers either in the backbone or in the side chains of the organic moiety. The presence of an inorganic element (metals and metal centers) in organic moieties has led to a number of new physicochemical properties while implementing novel functionality to the polymer matrix. This review covers nanotechnology influenced by distinctive features of metal‐containing macromolecular systems, particularly in developing flexible, functional materials. © 2013 Society of Chemical Industry     

Fast pyrolysis bio‐oil as precursor of thermosetting epoxy resins

Fast pyrolysis bio‐oil was employed as a source of phenolic compounds in the production of a bio‐based polymeric network. The bio‐oil was reacted with epichlorohydrin in alkaline medium using benzyltriethylammonium chloride as a phase transfer catalyst. The amount of free phenolic hydroxyl groups before and after modification was quantified through ³¹P‐NMR spectroscopy; and the epoxy content of the bio‐oil upon the chemical functionalization was measured by means of a titration using HBr in acetic acid solution. Grafting of epoxy functions onto the monomer`s structure was studied by FTIR. Likewise, α‐resorcylic acid was also modified with reactive epoxy moieties, and used as low molecular weight comonomer. The epoxidized derivatives of the bio‐oil were cured in epoxy polymers with 4‐dimethylaminopyridine. Thermo‐mechanical characterization showed that the obtained materials behave as thermoset amorphous polymers, exhibiting modulus values ranging from approximately 1.5–3.4 GPa at room temperature and glass transition temperatures above 100°C. POLYM. ENG. SCI., 58:1296–1307, 2018. © 2017 Society of Plastics Engineers     

Monte Carlo simulations of properties of side‐chain liquid‐crystal polymers

This paper presents a computational conformational study of side‐chain liquid‐crystal polymers to predict the optical and liquid‐crystalline properties of a series of polyepicholorohrdrin, polyacrylate, poly(methyl acrylate), and polystyrene‐based side‐chain polymers using a Monte Carlo simulation method. Some of the simulated side‐chain polymers were synthesised by chemical modification or polymerisation. The predictive capability of the orientational order parameter has been utilised to predict the liquid‐crystalline isotropic transition temperature of the investigated polymers, which was used to infer the type of distribution in the synthesised polymers. The predictive possibilities of this criterion are explored in the estimation of the nematic–isotropic transition temperatures of the simulated polymers. Evidence is presented to suggest that for side‐chain liquid‐crystalline polymer molecules the nematic to isotropic transition occurs when the order parameter reaches a value of 0.43 according to Maier–Saupe mean‐field theory. Copyright © 2006 Society of Chemical Industry     

Effect of glass transition temperature on heat‐responsive gas bubbles formation from polymers containing tert‐butoxycarbonyl moiety

Various types of polymers containing tert‐butoxycarbonyl (BOC) moiety as the typical protecting group of functional moieties have been used for the design of stimuli‐responsive polymer materials. In this study, we investigated the heat‐responsive deprotection behavior of BOC‐containing polymers obtained by radical polymerization of 4‐(tert‐butoxycarbonyloxy)styrene (BSt) and copolymerizations of BSt with styrene and methyl acrylate. The deprotection of BOC groups accompanying the evolution of isobutene and carbon dioxide as gaseous products was monitored by thermogravimetric analyses at different temperature circumstances; that is, on heating at a rate of 10 °C/min and under isothermal conditions at various temperatures. The deprotection resulted in a significant decrease in the transmittance of visible light due to the formation of a large number of gas bubbles, that is, foaming, in the polymer films when a heating temperature was close to the glass transition temperature of the used polymer. The potential of BOC‐containing polymers was also evaluated as the heat‐responsive adhesive polymers for dismantlable adhesion. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46252.     

Rheology of lubricating greases modified with reactive NCO‐terminated polymeric additives

A comprehensive rheological characterization of lithium lubricating greases modified with NCO‐terminated polymers has been performed in this work, with special emphasis on the effect of temperature. With this aim, NCO‐terminated polymers were prepared from several di‐ and tri‐functional polyols and polymeric MDI. Afterwards, the reaction between terminal isocyanate groups and 12‐hydroxystearate lithium soap, used as thickener for lubricating grease formulations, was promoted. Transient and steady‐state viscous flow, rheo‐destruction and stress relaxation tests were performed on the different samples studied. In this sense, the influence that temperature, free NCO content, molecular weight, and functionality of the reactive polymers exert on the rheological response of lubricating greases was analyzed. The most important rheological modification was achieved by using the lowest molecular weight polymer. In general, NCO‐terminated polymers significantly dampen the influence of temperature on the rheological functions of the additive‐free lubricating grease. In some cases, the viscosity and/or viscoelastic functions even increase with temperature, especially in formulations with residual free NCO groups. Several experimental flow problems, such as fracture and sample expelling from the measuring tool, are generally found, more frequently in formulations with high NCO content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modification of narrow‐spectrum peptidomimetic polyurethanes with fatty acid chains confers broad‐spectrum antibacterial activity

Each year, thousands of patients die from antimicrobial‐resistant bacterial infections that fail to respond to conventional antibiotic treatment. Antimicrobial polymers are a promising new method of combating antibiotic‐resistant bacterial infections. We have previously reported the synthesis of a series of narrow‐spectrum peptidomimetic antimicrobial polyurethanes that are effective against Gram‐negative bacteria, such as Escherichia coli; however, these polymers are not effective against Gram‐positive bacteria, such as Staphylococcus aureus. With the aim of understanding the correlation between chemical structure and antibacterial activity, we have subsequently developed three structural variants of these antimicrobial polyurethanes using post‐polymerization modification with decanoic acid and oleic acid. Our results show that such modifications converted the narrow‐spectrum antibacterial activity of these polymers into broad‐spectrum activity against Gram‐positive species such as S. aureus, however, also increasing their toxicity to mammalian cells. Mechanistic studies of bacterial membrane disruption illustrate the differences in antibacterial action between the various polymers. The results demonstrate the challenge of balancing antimicrobial activity and mammalian cell compatibility in the design of antimicrobial polymer compositions. © 2019 Society of Chemical Industry