Compatibilization Of Polymer Blends Research Articles

Enhancing Polymer Blend Compatibility with Linear and Complex Star Copolymer Architectures: A Monte Carlo Simulation Study with the Bond Fluctuation Model.

A Monte Carlo study of the compatibilization of A/B polymer blends has been performed using the bond fluctuation model. The considered compatibilizers are copolymer molecules composed of A and B blocks. Different types of copolymer structures have been included, namely, linear diblock and 4-block alternating copolymers, star block copolymers, miktoarm stars, and zipper stars. Zipper stars are composed of two arms of diblock copolymers arranged in alternate order (AB and BA) from the central unit, along with two homogeneous arms of A and B units. The compatibilization performance has been characterized by analyzing the equilibration of repulsion energy, the simulated scattering intensity obtained with opposite refractive indices for A and B, the profiles along a coordinate axis, the radial distribution functions, and the compatibilizer aggregation numbers. According to the results, linear alternate block copolymers, star block copolymers, and zipper stars exhibit significantly better compatibilization, with zipper stars showing slightly but consistently better performance.

A new approach for grafting plasticized cellulose acetate biodegradable plastic with maleic anhydride: Processing and characterization

AbstractGrafting polymers with reactive maleic anhydride is a common approach for the synthesis of new material with the capability of acting as a compatibilizer in polymer blends. Accordingly, this research showed a new approach for grafting maleic anhydride onto renewable cellulose acetate using an initiator. The grafting process through extrusion showed good stability with continuous production of all grafted samples. Moreover, two different grafting processes, namely one‐step and two‐step processes, were shown to produce materials with very similar characteristics. Grafting of maleic anhydride onto cellulose acetate by reacting with its hydroxyl groups was confirmed by both Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis. Rheological studies also demonstrated the enhanced flowability and lower viscosity of the grafted material in comparison to the plasticized cellulose acetate.Highlights Grafting maleic anhydride onto plasticized cellulose acetate by reactive extrusion. Detection of grafted maleic anhydride onto cellulose acetate through NMR analysis. High thermal stability of grafted materials. Significant reduction in viscosity of plasticized cellulose acetate after grafting

Methylation of softwood and hardwood kraft lignins with chloromethane.

Methylation is a well-established means of enhancing the thermal stability, improving the compatibility in polymer blends, and lowering the glass-transition temperature of lignins. This process normally involves reagents that are costly, associated with poor atom economy and/or highly toxic. Herein, we report the methylation of softwood and hardwood kraft lignins using chloromethane in alkaline aqueous media. This reaction proceeds in high yields at 90-110 °C under moderate pressure (40 psi) while generating environmentally benign sodium chloride and water as by-products.

Patchy stereocomplex micelles as efficient compatibilizers for polymer blends

Patchy spherical micelles prepared via stereocomplex-driven self-assembly are applied as efficient compatibilizers for highly immiscible polystyrene/poly(tert-butyl methacrylate) blends.

Improved physical, thermal, and biological properties of green synthesized Ag-containing nanocomposites of a novel chitosan-based blend

Different material compositions are being prepared to improve the physiochemical properties of chitosan biopolymer and thus to create new areas of use. This study presents new chitosan(CS)-based products based on synthetic polymers and biosynthesized AgNPs, prioritizing environmentally friendly synthesis methods. Methacrylate-based functional CP copolymer was prepared by the free radical polymerization method. Thanks to the amide, ester groups, and fluorine atoms in the side branch of the CP, a compatible polymer blend (CS-CP) was prepared by the environmentally friendly hydrothermal method through hydrogen bonds with CS. Again, with green synthesis applications, AgNPs were prepared from Prunus spinosa extract by hydrothermal method, and new nanocomposites were produced by adding CS-CPs at different weight ratios. The initial decomposition temperature of 245 °C, which indicates the thermal stability of CS-CP as determined by TGA, was increased to 268 °C with the addition of 7 % AgNPs. Adding CP to CS lowered the glass transition temperature, and this trend continued in nanocomposites with the addition of AgNPs. When CP was blended with CS, the oxidative stress index of CS increased from 18.26 AU to 65.45 AU. It was determined that this oxidative effect increased up to 181 AU when AgNPs were added. Thanks to this feature of the produced nanocomposites, it was found that the MIC (100–250 µg/mL for E. coli, 250–500 µg/mL for S. aureus and for 500–1000 µg/mL C. Albicans) values of CS against microorganisms decreased, and the antimicrobial activity increased. In addition, in studies with cancer (A549 and G361) cells, it was determined that even at low (25 µg/mL) doses, nanocomposites that included 5 % and 7 % AgNPs in their formula had anticarcinogenic activity. Further studies on biocompatibility may be recommended to confirm possible commercial benefits from the materials produced in future research.

Preparation of thermoplastic polyurethane blend foams with controlled hydrophobicity via vapor induced phase separation

AbstractOil–water separation has attained great attention due to recent concern in environmental safety. Porous material from tailored engineering is the best candidate to selectively adsorb oil from water. Among the various porous materials, polymer based adsorbent has several advantages over others, in terms of controllable porosity and functionality. Here, we propose thermoplastic polyurethane (TPU) based blend foam through vapor induced phase separation method as a potential candidate for oil–water separation. In order to adjust hydrophobicity and compatibility of TPU blend, PDMS‐based TPU (Si‐TPU) is designed and synthesized to be blended with commercialized TPU. Si‐TPU with tailored weight ratio (PDMS/PTHF = 4/6) in synthetic level make it possible to achieve both of demanded hydrophobicity (the water contact angle increased from 85.19 ± 1.83° to 121.15 ± 3.79° after adding Si‐TPU) and controlling compatibility with CTPU during VIPS foaming. Thus, these well‐designed Si‐TPU can be utilized in various fields such as improving compatibility of polymer blend, adsorption efficiency of oil, and smart filtration, and so forth.

Effects of sulfonation degree on compatibility and separation performance of polybenzimidazole (PBI)-sulfonated polyphenylenesulfone (sPPSU) blend membranes

The molecular compatibility between polybenzimidazole (PBI) and sulfonated polyphenylsulfone (sPPSU) and their blend membranes for herbicide removal in water reuse and for drug separation in organic solvent nanofiltration (OSN) have been investigated as a function of sulfonation degree in sPPSU. Flat sheet membranes cast from PBI-sPPSU blends with a mass ratio of 1:1 were prepared and then crosslinked by trimesoyl chloride (TMC) at room temperature. The blend made of PBI and 12.7 mol% sPPSU showed high compatibility based on the calculated enthalpy of mixing (ΔHm), measured dope viscosity, phase diagram, and single Tg. The TMC modified membrane cast from this composition also exhibited higher chemical resistance, mechanical stability, narrower pore size and pore size distribution, macrovoid-free structure and better separation performance. All fabricated membranes were evaluated using feeds containing tetracycline (MW = 444 Da) as a model drug in ethanol and pendimethalin (MW = 281.3 Da) as a model herbicide in water. The crosslinked PBI-12.7 mol% sPPSU (12.7C) membrane exhibited rejection of >96% against low-molecular-weight pendimethalin from water and tetracycline from ethanol. It also has the capability to separate mixed solutes, even with small molecular weights. This study illustrates the effectiveness of highly compatible polymer blends with the aid of one-step cross-linking modification for nanofiltration.

Compatibilization of Polymer Blends by Ionic Bonding

Chemically dissimilar polymers are rarely miscible due to a specific entropy of mixing that scales as 1/N, where N is the degree of polymerization. As a consequence, the compatibilization of immiscible polymer blends presents a major challenge to plastics recycling efforts. We demonstrate that when the chain ends of two highly immiscible polymers are functionalized with reacting acid and base groups, ionic junctions form in situ by proton transfer, leading to the stabilization of interfaces and the suppression of macroscopic phase separation. Due to the dynamic nature of proton transfer, the microstructure can be tuned via ionic bond energy (h) and segregation strength (χN). In this work, a library of ionically end-functionalized polystyrene (PS) and polydimethylsiloxane (PDMS) is used to demonstrate the importance of end-group acidity/basicity and molecular weight on compatibilization. Well-ordered lamellae result from blending polymers with strong acid and base units, while less ordered, more swollen microphases occur in systems with weak acid and base end groups or larger molar mass. Heating the ionic blends results in reverse proton transfer and destruction of the close-contact ion pairs. As a result, domains are swollen with the resulting unbonded homopolymers, which in sufficient amounts, leads to macrophase separation. Moreover, external salt ions screen the electrostatic attractions and disturb ionic compatibilization. The self-consistent field theory (SCFT) of this system reveals that the ionic interactions can be tuned to create a broad range of morphologies, from microphases to macrophases.

Compatibilized bio-based polybutylene-succinate blended composites filled with surface modified Si3N4 for improved rigidity and thermal performance

In this study, polybutylene succinate was melt blended with polypropylene (PP) to fabricate partially bio-based and miscible composites filled with various loading silicon nitride (Si3N4) particles. Oleic acid and PP-grafted maleic anhydride were used as a functionalizing agent for Si3N4 and as a compatibilizer for polymer blends, respectively. The surface functionalization of the Si3N4 particles enhanced the interfacial adhesion between the filler and the blended polymers, affecting the thermal and mechanical properties of the composites. The thermal conductivity of the composite filled with only 18.6 vol% surface-treated Si3N4 increased by 342% compared to that of the blended polymer. In addition, the surface treatment of Si3N4 significantly improved the Young’s modulus, tensile strength, and thermal stability of the corresponding composites. However, the temperature-dependent storage modulus was unaffected by the surface treatment of Si3N4 and increased as the loading content of the Si3N4 particles increased.

Increases in Miscibility of a Binary Polymer Blend Confined within a Nanoparticle Packing

Despite various physical and chemical strategies that have been explored, compatibilization of polymer blends has proved elusive. Confinement of polymers has shown to induce substantial and at times unexpected changes in glass-transition temperature, dynamics, and morphology of these materials. Although confinement of blends to thin films have shown to influence phase separation structure and chain mobility, the impact of confinement on the miscibility of polymer mixtures is much less understood. Here, we present a computational study using field-theoretic simulations to understand the thermodynamics of polymer blends that are confined in the interstices of nanoparticle packings where both polymers have neutral interactions with the nanoparticle surfaces. We calculate their binodal phase envelopes and show that two polymers that would undergo macroscopic phase separation become miscible when they are subjected to extreme nanoconfinement. The strength of the repulsion required to induce phase separation increases significantly as confinement increases. We find that this enhanced miscibility is driven by both an increase in entropic penalty upon phase separation and a decrease in enthalpic repulsion with increasing confinement. We relate the change in enthalpy to a reduction in the number of polymer–polymer contacts near nanoparticle surfaces and the change in entropy to a reduction in conformational freedom due to the formation of a polymer–polymer interface near nanoparticle surfaces. Confinement-induced mixing of polymers in nanoparticle packings could enable precise tuning of mechanical and transport properties of nanocomposite films and membranes.

The Effect of Oleic Acid-Grafted Linear Low-Density Polyethylene as Compatibilizer on the Properties of Linear Low-Density Polyethylene/Cyclic Natural Rubber Blends

In this paper, we report that the compatibility of polymer blends between linear low-density polyethylene (LLDPE) and cyclic natural rubber (CNR) can be increased by the addition of oleic acid-grafted linear low-density polyethylene. The research aims to investigate the effect of LLDPE-g-OA compatibilizer in LLDPE/CNR blends on improving the mechanical properties and characteristics of the blends. The LLDPE/CNR/LLDPE-g-OA blends (compatible blends) were prepared by blending methods in the molten phase using an internal mixer set at a temperature of 160oC with a rotation speed of 100 rpm. The LLDPE pellets were inserted into it until melts and followed with an addition of CNR and LLDPE-g-OA. The tensile strength test results have shown an increase in mechanical properties after the addition of the compatibilizer with a maximum content of 4 wt%. The difference in FTIR spectra of compatible blends is indicated by the presence of C=C bonds from CNR, which appear at 1654.9 cm-1, indicating the occurrence of physical bonds in the blends. The existence of the LLDPE-g-OA compatibilizer has increased the thermal stability of the polymer blends and changes in the melting point temperature of 1240C. Compatible blends showed that the surface morphology was smoother, and there were significant microstructural changes compared to incompatible blends.

Dihydroxy Polyethylene Additives for Compatibilization and Mechanical Recycling of Polyethylene Terephthalate/Polyethylene Mixed Plastic Waste.

Polymer blend compatibilization is an attractive solution for mechanical recycling of mixed plastic waste because it can result in tough blends. In this work, hydroxy-telechelic polyethylene (HOPEOH) reactive additives were used to compatibilize blends of polyethylene terephthalate (PET) and linear low-density polyethylene (LLDPE). HOPEOH additives were synthesized with molar masses of 1-20 kg/mol by ring-opening metathesis polymerization of cyclooctene followed by catalytic hydrogenation. Melt-compounded blends containing 0.5 wt % HOPEOH displayed reduced dispersed phase LLDPE particle sizes with ductilities comparable to virgin PET and almost seven times greater than neat blends, regardless of additive molar mass. In contrast, analogous blends containing monohydroxy PE additives of comparable molar masses did not result in compatibilization even at 2 wt % loading. The results strongly suggest that both hydroxy ends of HOPEOH undergo transesterification reactions during melt mixing with PET to form predominantly PET-PE-PET triblock copolymers at the interface of the dispersed and matrix phases. We hypothesize that the triblock copolymer compatibilizers localized at the interface form trapped entanglements of the PE midblocks with nearby LLDPE homopolymer chains by a hook-and-clasp mechanism. Finally, HOPEOH compounds were able to efficiently compatibilize blends derived solely from postconsumer PET and PE bottles and film, suggesting their industrial applicability.

Induced Smectic E Phase in a Binary Blend of Side-Chain Liquid Crystalline Polymers.

Two liquid crystalline polymers containing an azobenzene or cyanobiphenyl mesogenic side chain that adopt smectic A phases are mechanically mixed at 1:1 mesogen molar ratio at an isotropic phase temperature and then cooled. The resultant binary polymer mixture behaves like a single component as revealed by polarized microscopy observation and differential scanning calorimetry, indicating that the binary mixture forms a fully compatible polymer blend. Moreover, the simple polymer blend unexpectedly leads to a higher-ordered smectic E phase where a herringbone structure is formed with restricted mesogen axis rotation. These results suggest a specific intermolecular interaction between the two mesogens, thereby inducing unusual compatibilized polymer blends and the most ordered liquid crystal (LC) phase.

Surface-Compartmentalized Micelles by Stereocomplex-Driven Self-Assembly.

The unique corona structure of surface-compartmentalized micelles (Janus micelles, patchy micelles) opens highly relevant applications, e.g. as efficient particulate surfactants for emulsion stabilization or compatibilization of polymer blends. Here, stereocomplex-driven self-assembly (SCDSA) as a facile route to micelles with a semicrystalline stereocomplex (SC) core and a patch-like microphase separated corona, employing diblock copolymers with enantiomeric poly(L-lactide)/poly(D-lactide) blocks and highly incompatible corona-forming blocks (polystyrene (PS), poly(tert-butyl methacrylate)) is introduced. The spherical patchy SC micelles feature a narrow size distribution and show a compartmentalized, shamrock-like corona structure. Compared to SC micelles with a homogeneous PS corona the patchy micelles have a significantly higher interfacial activity attributable to the synergistic combination of an amphiphilic corona with the Pickering effect of nanoparticles. The patchy micelles are successfully employed in the stabilization of emulsions, underlining their application potential.

Compatibilization of Immiscible Polymer Blends Using Block Copolymer: Influence of the Dry Brush Model Modifications on Model Results

AbstractThe compatibilization of polymer blends using a copolymer can be estimated, among other, using simple theoretical models based on Leibler's mean field theory and its modification by Noolandi. The case when copolymer chain is shorter than homopolymer chains can be described in the “dry brush” approximation for high concentration of the copolymer in the interfacial layer and in the approximation for the low copolymer concentration in the interfacial layer. Since, there is a discontinuity between results provided by them, the effect of several modifications of the dry brush approximation has been studied. None of the tried modifications shifts results closer to the approximation of the low copolymer concentration.

Blends Containing Amphiphilic Biopolymers and their Compatibility Behavior

Abstract: This mini-review deals with the miscibility behaviour of two biopolymers, chitosan and alginate. It is well known that the miscibility in multifunctional polymer blends is favoured due to specific interactions, which origin a negative heat of mixing. Particular interest is focused on functionalized polymers because they are the most suitable way to obtain interacting polymers, producing a single-phase material. Due to the polyfunctionality of chitosan (CS) and other biopolymers, they can be taken into account as a basis of a strongly interacting polymer. They would allow obtaining compatible polymeric materials. For this reason, blends containing CS with different vinyl polymers have been studied. The most significant polymeric blends with these natural polymers will be analyzed in this review. Chitosan is obtained from the biopolymer chitin through sequential processes of demineralization, deproteinization and deacetylation. The native chitin is obtained by direct separation from the marine crustaceans shell, which is abundant on the sea coasts. Some classic results that relate to the polymeric blends containing amphiphilic polymers will be discussed. Another biopolymer of the coast is Sodium Alginate (SA). Alginate also allows the formation of compatible polymer blends. Results in this regard will also be analyzed in this review.

Mechanical, Thermal and Morphological Properties of Poly(Lactic Acid) and Poly(Butylene Adipate-co-Terephthalate) Blends with Organoclay

This work studied the effect of nanoclay surface modified with 25-30 wt% of methyl dihydroxyethyl hydrogenated tallow ammonium (Clay-DHA) on morphological, mechanical and thermal properties of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) blends. The PLA/PBAT (75/25 w/w) blends without and with Clay-DHA were melt mixed by an internal mixer and molded by compression method. The morphological analysis observed the phase separation of PLA/PBAT blends due to minor PBAT phase dispersed as spherical shape in PLA phase, indicating a poor interfacial adhesion between PLA and PBAT phases. The incorporation of Clay-DHA could improve the compatibility of polymer blends. The tensile testing found that the addition of Clay-DHA 1 and 3 phr increased Young’s modulus of PLA/PBAT blends. The addition of Clay-DHA decreased the strain at break of PLA/PBAT blends. The thermal degradation of PLA/PBAT blends and composites showed the similar thermal degradation process step. The addition of Clay-DHA was no effect on thermal stability and thermal properties of PLA/PBAT blends.

RAFT-Based Polymers for Click Reactions.

The parallel development of reversible deactivation radical polymerization and click reaction concepts significantly enriches the toolbox of synthetic polymer chemistry. The synergistic effect of combining these approaches manifests itself in a growth of interest to the design of well-defined functional polymers and their controlled conjugation with biomolecules, drugs, and inorganic surfaces. In this review, we discuss the results obtained with reversible addition–fragmentation chain transfer (RAFT) polymerization and different types of click reactions on low- and high-molar-mass reactants. Our classification of literature sources is based on the typical structure of macromolecules produced by the RAFT technique. The review addresses click reactions, immediate or preceded by a modification of another type, on the leaving and stabilizing groups inherited by a growing macromolecule from the chain transfer agent, as well as on the side groups coming from monomers entering the polymerization process. Architecture and self-assembling properties of the resulting polymers are briefly discussed with regard to their potential functional applications, which include drug delivery, protein recognition, anti-fouling and anti-corrosion coatings, the compatibilization of polymer blends, the modification of fillers to increase their dispersibility in polymer matrices, etc.

Linear, Graft, and Beyond: Multiblock Copolymers as Next-Generation Compatibilizers.

Properly addressing the global issue of unsustainable plastic waste generation and accumulation will require a confluence of technological breakthroughs on various fronts. Mechanical recycling of plastic waste into polymer blends is one method expected to contribute to a solution. Due to phase separation of individual components, mechanical recycling of mixed polymer waste streams generally results in an unsuitable material with substantially reduced performance. However, when an appropriately designed compatibilizer is used, the recycled blend can have competitive properties to virgin materials. In its current state, polymer blend compatibilization is usually not cost-effective compared to traditional waste management, but further technical development and optimization will be essential for driving future cost competitiveness. Historically, effective compatibilizers have been diblock copolymers or in situ generated graft copolymers, but recent progress shows there is great potential for multiblock copolymer compatibilizers. In this perspective, we lay out recent advances in synthesis and understanding for two types of multiblock copolymers currently being developed as blend compatibilizers: linear and graft. Importantly, studies of appropriately designed copolymers have shown them to efficiently compatibilize model binary blends at concentrations as low as ∼0.2 wt %. These investigations pave the way for studies on more complex (ternary or higher) mixed waste streams that will require novel compatibilizer architectures. Given the progress outlined here, we believe that multiblock copolymers offer a practical and promising solution to help close the loop on plastic waste. While a complete discussion of the implementation of this technology would entail infrastructural, policy, and social developments, they are outside the scope of this perspective which instead focuses on material design considerations and the technical advancements of block copolymer compatibilizers.

Novel approaches for functionalization of polypropylene by maleimides

The hydrophobic character of polypropylene (PP) limits its miscibility with more hydrophilic components and fillers. One approach to answer this challenge is the PP functionalization with hydrophilic groups such as maleimides which improves the compatibility in polymer blends and composites, but also improves the thermal stability, allows self-healing or thermal responsivity of the material. In this study, a maleimide-functionalized PP was prepared by the process of reactive grafting with three methods differing in the feed composition: Method A – one-step process, method B – grafting of PP with maleic anhydride and subsequent reaction with amine and method C – reaction between maleic anhydride and amine to form maleimide and subsequent radical grafting of maleimide onto PP backbone. Functionalization was performed with two low molecular weight aromatic amines (aniline, 4-aminophenol) and two high molecular weight aliphatic amines. Maleimide-functionalized PP was also prepared by direct grafting of N-phenylmaleamic acid in the presence of a desiccant that induced a dehydration, forming the maleimide on the PP backbone. The presence of maleimide units were identified by Fourier transform infrared spectroscopy (FTIR). Effect of functionalization on thermal and rheological properties was analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and melt volume rate measurement (MVR). Direct grafting of maleamic acid simplifies the technological process of functionalization and provides material and time savings.