Blend Interface Research Articles

Determining the optimal molecular architecture for reactive splicing compatibilization: Toward a better understanding of reactive polymer processing

Reactive polymer processing is an effective and environmentally-friendly means of preparing new materials based on combining components with various properties. Numerous investigations have been carried out to explore the reaction processes that occur during the melt blending of polymers. However, reactive processing is far from fully understood because it involves a complicated combination of shear and extensional flows as well as high temperatures and pressures. In this work, a two-step compatibilizing strategy (called reactive splicing compatibilization) has been used to compatibilize immiscible Poly(lactic acid) (PLLA)/Poly(butylene adipate-co-terephthalate) (PBAT) blends with two different PBAT molecular weights (termed H-PBAT and L-PBAT, respectively), using styrene-co-glycidyl methacrylate (SG) as the grafting counterpart. Reactive compatibilizers with various architectures were prepared by pre-grafting either PLLA or PBAT (or both) onto the SG main chains. The remaining unreacted epoxide groups of the pregrafted SG underwent in situ reactions to form double grafted copolymers as compatibilizers for the final blends. The reactivity of SG with these polymers was found to decrease in the order of L-PBAT > PLLA > H-PBAT. Reactive compatibilizers having various architectures were applied to PLLA/PBAT blends with compositions ranging from 90/10 to 10/90 (w/w). The most efficient pre-grafted reactive compatibilizer was determined for the blends with certain composition. A higher proportion of H-PBAT had to be pre-grafted onto the SG to achieve the best compatibilization efficiency when increasing the PLLA content in PLLA/H-PBAT blends. In the case of PLLA/L-PBAT blends, PLLA chains had to be pre-grafted onto the SG for the best compatibilization when L-PBAT was the primary component of the blend. These results provide a better understanding of the reactive processing mechanism. Evidently, the dynamic shear applied during melt processing continuously renews the interface between the different phases to provide sites for reactions between the blend components. These reactions are affected by both the reactivity of the components and the contact time, which in turn is determined by the blend composition. The compatibilizers located at the blend interface were found to have very similar symmetrical binary grafted structures for blends with different compositions.

Influence of polypropylene and nanoclay on thermal and thermo-oxidative degradation of poly(lactide acid): TG-FTIR, TG-DSC studies and kinetic analysis

Compatibilized poly(lactic acid)/polypropylene (PLA/PP) blends with a drop-matrix morphology containing 25 wt.% PP, 5 wt.% ethylene/n-butyl acrylate/glycidyl methacrylate terpolymer (PTW) as compatibilizer, and 5 wt.% nanoclay were prepared by one-step mixing process in a twin-screw extruder. TEM analysis revealed that the clay particles were mainly localized in the PLA matrix phase in the absence of PTW; by contrast, the addition of compatibilizer changed the location to the blend interface. Multiple rate thermogravimetric analysis revealed two-stage and single-stage weight losses under neutral and air atmospheres, respectively. To reveal the influence of blending, nanoclay inclusion and compatibilization process on the PLA degradation process, a systematic quantitative evaluation of degradation processes was carried out based on kinetic parameters derived from model-free and model-fitting analyses. The results revealed that the activation energy of the thermo-oxidative process, being significantly lower than that of the thermal pyrolysis, greatly increases in the presence of nanoclay, indicating the accelerating role of oxygen in the degradation process and the barrier effect of nanoclay against oxygen diffusion. The combined TG-DSC analysis in the nitrogen environment confirmed the appearance of endothermic signals being proportional to the sample weight loss, which is characteristic of thermal pyrolysis. Subsequently, in an oxygen-containing environment, initial exothermic peaks were formed, which was attributed to the oxidative degradation of the sample. As the reaction progressed, secondary peaks were observed due to the degradation of residuals formed in the first stage of the degradation process. Also, for chemical analysis of volatiles, simultaneous TG-FTIR analysis was employed in a neutral atmosphere at the maximum degradation temperature. Lactide, acetaldehyde, carbon dioxide (CO2) and carbon monoxide (CO) were the products obtained from the degradation process of the PLA phase.

Assessment of compatibilization role of nanoclay in immiscible polystyrene/ethylene–octene copolymer blends via wide‐angle X‐ray scattering, microstructure, rheological analyses, and mechanical properties

ABSTRACTPolystyrene (PS)/ethylene–octene copolymer (EOC) blends with 80/20 wt % composition containing different amounts (0, 1.0, 2.5, 5.0 and 7.5 wt %) of an organically modified nanoclay were prepared by one‐step melt‐mixing method. Also, the EOC‐rich blends with 80 wt % EOC content loaded with 0 and 5.0 wt % of the nanoclay were prepared under the similar processing conditions. Presence of both PS and EOC chains in between clay layers localized at the interface of the blends could be deduced by X‐ray diffraction analysis, which suggested formation possibility of PS‐EOC physical structures at the blend interface. Transmission electron microscopy results confirmed that clay nanoparticles were mainly localized at the interface of the blends and also partly in the PS and EOC components of the systems. The localization of the nanoclay was also described by the linear viscoelastic melt rheological studies. It is also revealed that nanoclay had stronger interactions with PS than EOC. This is reflected in the higher tensile properties in the PS‐rich system. The analysis of morphology of the developed systems by emulsification curve revealed that the optimum amount of nanoclay to modify PS‐rich blend is 2.5 wt %. At this clay loading, the blend exhibited the highest impact resistance. According to the overall results, suitability of nanoclay was confirmed for compatibilization of the PS/EOC blends. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48748.

Silane‐Modified Graphene Oxide as a Compatibilizer and Reinforcing Nanoparticle for Immiscible PP/PA Blends

Graphene oxide (GO) and aminosilane (AS)‐modified GO (GOAS) have been studied as possible compatibilizers for immiscible polyblends. Ideally, for localization of nanoparticles (NPs) at the interface, the thermodynamics of the constituents and mixing dynamics have to be tailored and controlled, respectively. Accordingly, a variety of oxidation levels (10%–40%) of GOs were prepared using Hummer's method and further modified by AS. Experimental results indicated that the GO goes through thermal reduction (above 200°C) during blending and reduced GO (rGO) is produced. The GOAS moderated the reduction reaction and stabilized the GO. The thermodynamic wetting coefficient of PP (polypropylene)/PA (polyamide)/rGOAS system was shown to drive the rGOAS from the PP phase to the blend's interface during time‐controlled blending. The localization of the rGOAS at the interface resulted in significant enhancement of mechanical properties using only 2–3 wt% of rGOAS. Over 100% enhancement in strength, 40% enhancement in modulus, and 30% in toughness were shown, compared with neat PP/PA. Reduced GOAS and its location at the interface resulted in a third glass transition temperature (Tg), in addition to the PP and PA respective Tgs. Rheological percolation at 2–3 wt% rGOAS (20%) supports the localization of rGOAS at the interface. Storage moduli increase with interfacial tension, in accordance to the rheological models. POLYM. ENG. SCI., 60:180–191, 2020. © 2019 Society of Plastics Engineers

Carbon nanotube localization at interface in cocontinuous blends of polyethylene and polycarbonate

ABSTRACTA new technique to show good electroconductivity was proposed using carbon nanotube (CNT) localization in cocontinuous immiscible polymer blends comprising ultrahigh‐molecular‐weight polyethylene (UHMWPE) and polycarbonate (PC). When UHMWPE was added to PC/CNT in the molten state in an internal mixer, CNTs started moving to the UHMWPE phase. However, CNTs require a long time to diffuse into the UHMWPE phase owing to a low diffusion constant. Consequently, they remain at the interface between PC and UHMWPE. When the blends have cocontinuous structure, the localized CNTs at the phase boundary act as a conductive path, leading to a good electroconductivity. Although a similar morphology is obtained by adjusting the balance of interfacial tensions among polymers and CNT, it is difficult to find a system showing appropriate interfacial tensions. As the present method is applicable to various polymer blends, it will be an important technique to prepare a conductive nanocomposite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48676.

Unraveling the Effect of 3D Particle Localization on Coarsening Dynamics and Rheological Properties in Cocontinuous Polymer Blend Nanocomposites

Localization of nanoparticles at the interface of cocontinuous blends provides a way to enhance polymer blend properties as well as prepare surface-modified porous materials (via removal of one ble...

Effect of the blending processes on selective localization and thermal conductivity of BN in PP/EPDM Co-continuous blends

In this study, the co-continuous blends of polypropylene (PP) and ethylene propylene diene rubber (EPDM) were prepared. Boron nitride (BN) nanoparticles were introduced into PP/EPDM blends by different blending processes to prepare the thermal composites. Solvent extraction, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to investigate the location of BN in the immiscible polymer blends. Through controlling the blending process, the BN nanoparticles could be selectively distributed at the PP phase, EPDM phase or interface of the polymer blends. The results showed that BN selectively located in the PP phase can achieve have the highest thermal conductivity when the BN nanoparticles were firstly mixed with PP phase. In addition, the influence of the different mass ratio of PP and EPDM on the thermal properties was also investigated. The blends with the mass ratio of PP/EPDM 50/50 have the highest thermal conductivity.

An assessment on the effect of trifluoropropyl-POSS and blend composition on morphological, thermal and thermomechanical properties of PLA/TPU

The influence of blending ratio and trifluoropropyl polyhedral oligomeric silsesquioxane (POSS) on microstructure, melt and cold crystallization behavior, thermomechanical and thermal stability of melt-blended polylactic acid/thermoplastic polyurethane (PLA/TPU) blends was investigated using various techniques. Morphological observations (TEM and EDX) showed that POSS nanoparticles have a good dispersion state throughout the matrix and localize in both phases and also at the blend interface. POSS nanoparticles hindered the melt crystallization of PLA while enhancing the degree of cold crystallinity of PLA. In addition, the dispersed TPU droplets in PLA matrix induced a nucleation effect on melt crystallization of PLA, especially at low contents. On the contrary, the cold crystallization temperature of PLA shifted to a higher temperature in the presence of TPU phase, but the degree of crystallinity improved in the case of heating with a low rate. Although the addition of TPU to PLA resulted in a decrement in onset degradation temperature, the samples degraded in wider ranges than neat PLA. The onset degradation temperature of samples in inert ambient was declined by the addition of POSS due to its low thermal stability. These nanoparticles slightly enhanced the thermal stability of PLA-rich samples in air ambient but had no sensible effect on TPU-rich samples. The storage modulus values of the PLA/TPU blends gradually decreased with increasing TPU content. In addition, incorporation of POSS nanoparticles, generally, increased the values of storage modulus but reduced the glass transition temperature, proving the lubrication effect of POSS nanoparticles.

Strategies for interfacial localization of graphene/polyethylene‐based cocontinuous blends for electrical percolation

AbstractWe have investigated melt blending approaches to interfacial localization of few‐layer graphene in cocontinuous polymer blends with polyethylene as one of the components. When linear low‐density polyethylene (LLDPE)/polypropylene (PP) or high‐density polyethylene (HDPE)/polylactic acid (PLA) and graphene were mixed all together, graphene preferred polyethylene over PP or PLA. When PP and graphene were premixed and blended with polyethylene, some graphene was trapped at the blend interface but not enough to cover the large interfacial area. In contrast, an ultralow electrical percolation was achieved (< 0.1 vol%) in HDPE/PLA blend due to smaller interfacial area. In another approach, polystyrene was added as a tertiary minor component to HDPE/PLA blends. This continuous interfacial layer containing graphene led to a low electrical percolation threshold (< 0.2 vol%). From these investigations, we suggest general ways to reduce a percolation threshold by kinetic control of the morphology of cocontinuous polymer blends.

Tailoring the electrical and thermal conductivity of multi-component and multi-phase polymer composites

ABSTRACTThe majority of polymers are electrical and thermal insulators. In order to create electrically active and thermally conductive polymers and composites, the hybrid-filler systems is an effective approach, i.e. combining different types of fillers with different dimensions, in order to facilitate the formation of interconnected conducting networks and to enhance the electrical, thermal, mechanical and processing properties synergistically. By tailoring polymer-filler interactions both thermodynamically and kinetically, the selective localisation of fillers in polymer blends and at the interface of co-continuous polymer blends can enhance the electrical conductivity at a low percolation threshold. Moreover, selective localisation of different filler types in different co-continuous phases can result in multiple functionalities, such as high electrical conductivity, thermal conductivity or electromagnetic interference shielding. In this review, we discuss the latest progress towards the development of electrically active and thermally conductive polymer composites, and highlight the technical challenges and future research directions.

Synergistic toughening of carbon nanotubes and nucleating agent in polypropylene/ethylene-propylene-diene terpolymer blend

A few carbon nanotubes (CNTs) and 1,2,3,4-bis(3,4-dimethylbenzylidene sorbitol (DMDBS) were incorporated into polypropylene/ethylene-propylene-diene terpolymer (PP/EPDM) (85/15, wt/wt) blends. It was found that DMDBS exhibited excellent nucleation effect on the crystallization of PP matrix, while its nucleation effect was weakened to a certain extent in the samples containing CNTs. Slightly changed localization state of CNTs from EPDM component to the blend interface was induced by DMDBS. Mechanical property measurements showed that compared with the low impact strength of the binary PP/EPDM (13.5 kJ/m2), greatly enhanced impact strength (51.2 kJ/m2) was achieved for the sample containing 1 wt% CNTs and 0.2 wt% DMDBS, which was also different from the slight enhancement of impact strength induced by adding only CNTs (18.8 kJ/m2) or DMDBS (16.3 kJ/m2). The synergistic toughening mechanisms of CNTs and DMDBS are attributed to the much reduced PP spherulites and the bridging effect of CNTs at the blend interface, which both facilitate the stress transferring from EPDM particles to PP matrix.

Aspects regarding the efficiency of nanosilica as an interfacial compatibilizer of a polypropylene/ethylene vinyl-acetate immiscible blend

The effects of blending sequence and residence time on the efficiency of nanosilica as an interfacial compatibilizer of an immiscible blend of polypropylene and ethylene vinyl-acetate (PP/EVA) with unstable droplet-matrix morphology, melt-compounded in a twin-screw extruder, was investigated. Morphological analysis revealed that the nanosilica particles are adsorbed at the blend interface, irrespective of the processing conditions adopted, which is in good agreement with predictions based on the thermodynamic interactions, kinetics of mixing and rheological parameters. It was observed that the effectiveness of interfacial nanosilica in the compatibilization of the PP/EVA blend is greatly dependent on the mixing time, and the blending sequence is less important. The size of the EVA droplets is reduced when PP/EVA blends are processed with longer residence times, and increases with shorter mixing times. The results reported herein and in a previous publication [Polym Test 34 (2014) 175–182] suggest that the interfacial nanosilica layer does, in fact, inhibit the coalescence while at the same time hindering the break-up of EVA droplets during the PP/EVA melt blending, with the net effect being dependent on the magnitude of these two time-related mechanisms.

Statistical adhesion strength of an amorphous polymer–its miscible blend interface self-healed at a temperature below the bulk glass transition temperature

ABSTRACTThe distribution of the lap-shear strength developed at an amorphous asymmetric compatible interface between the contacting thick (bulk) films of entangled polystyrene (PS) with its miscible blend with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) (75 wt.% PS and 25 wt.% PPO) at a constant healing temperature (T) of 90°C has been analyzed by using a Weibull statistical model. This T was below the bulk glass transition temperatures (Tgbulk) of PS and PS-PPO blend of 103°C and 121°C, respectively, but above the surface glass transition temperatures (Tgsurface) of PS of 55°C and of the blend of 83°C. The so-called Weibull modulus and the scale parameter have been estimated for the partially self-healed PS–(PS-PPO blend) interface and analyzed as a function of healing time. The results obtained have been discussed and compared with those reported recently for the PS and poly(methyl methacrylate) interfaces.

Compatibilization of silicone/fluorosilicone blends by dynamic crosslinking and fumed silica addition

The aim of this work is to study the compatibility of silicone/fluorosilicone blends by exploring two compatibilization strategies. First, the crosslinking of the blend under shearing conditions leads to a reduction in the size of the fluorosilicone domain and hence to an effective stabilization of the morphology under shear and long time annealing. The refinement of the morphology in the dynamic crosslinking step is most likely due to a decrease in the viscosity ratio coming from preferential crosslinking of the fluorosilicone phase. However, the formation of a copolymer between silicone and fluorosilicone at the blend interface cannot be totally excluded. Secondly, the silicone/fluorosilicone blend was compatibilized by the addition of silica particles whose surface is hydrophilic or hydrophobic. Fumed hydrophilic silica allows to reduce the size of the fluorosilicone phase up to 500 nm while its hydrophobic counterpart is ineffective. This observation has been attributed to the specific hydrogen and dipolar interactions of the silicone and the CF3 group with the silanol present on the surface of the hydrophilic silica. The compatibilization mechanism is supposed to be due to a decrease in the interfacial tension and to a reduction of the coalescence phenomenon.

Enhanced Interfacial Adhesion by Reactive Carbon Nanotubes: New Route to High-Performance Immiscible Polymer Blend Nanocomposites with Simultaneously Enhanced Toughness, Tensile Strength, and Electrical Conductivity.

Physically anchoring carbon nanotubes (CNTs) onto the interface of immiscible polymer blends has been extensively reported; however, enhancement of physical properties of the blends has seldom been achieved. Herein, we used CNTs with reactive epoxide groups and long poly(methyl methacrylate) (PMMA) tails as a thermodynamic compatibilizer for immiscible poly vinylidene fluoride/poly l-lactide (PVDF/PLLA) blends. The CNTs acted as an efficient compatibilizer and bridged the two phases through physical entanglement and chemical reaction. The sea-island structure of the blend transformed into a bicontinuous structure for CNT contents greater than 3 wt %. The mechanical properties, including ductility and tensile strength, thermal properties, and electrical conductivities were all enhanced by the CNTs compatibilizer. This strategy thermodynamically compatibilized by reactive nanofillers paves the way for advanced blend nanocomposites.

Compatibilization of acrylonitrile-butadiene-styrene terpolymer/poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) blend: effect on morphology, interface, mechanical properties and hydrophilicity

The compatibilization of acrylonitrile-butadiene-styrene terpolymer (ABS) and poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) blends was first investigated. Styrene-acrylonitrile-glycidyl methacrylate terpolymer (SAG) and ABS grafted with maleic anhydride (ABS-g-MAH) were selected as reactive compatibilizers for the ABS/PETG blends. The compatibilization effect was assessed by scanning electron microscope (SEM), differential scanning calorimetry (DSC) and mechanical properties. And the effect of compatibilizers on the hydrophilicity of the blends was evaluated as well. SEM observation and DSC analysis confirmed that both SAG and ABS-g-MAH compatibilizers could improve the compatibility between ABS and PETG, leading to an improvement in toughness of the blend. The possible cause for the improvement of compatibility was the reaction between compatibilizers and PETG, which could in situ turn out compatibilizers that acted as interfacial agents to enhance the interfacial interaction in the blend. Especially, the addition of SAG significantly decreased the dispersion phase size and the interface voids almost disappeared. Since the in situ reactions between the epoxy groups of SAG and the end groups (COOH or OH) of PETG generated PETG-co-SAG copolymer at the blend interface, and the cross-linking reactions proposed to take place between SAG and the PETG-co-SAG copolymer, acting as compatibilizer, could significantly increase the interfacial interaction. The addition of SAG also enhanced the stiffness of the blends. Moreover, the addition of SAG made the blend more hydrophilic, whereas the addition of ABS-g-MAH made the blend more hydrophobic. Therefore, SAG was a good compatibilizer for the ABS/PETG blends and could simultaneously provide the blends with toughening, stiffening and hydrophilic effects.

Kinetic Control of Graphene Localization in Co-continuous Polymer Blends via Melt Compounding.

Selective localization of graphene in co-continuous polymer blends is an attractive method for preparing conductive polymer composites. Localization of graphene at the interface between the two polymer phases produces good conductivity at ultra-low concentrations. Although graphene localization is ultimately dependent on thermodynamic factors such as the surface energy of graphene and the two polymer components, kinetics also strongly affects the migration and localization of graphene in polymer blends during melt compounding. However, few studies have systemically investigated the important role of kinetics on graphene localization. Here, we introduced graphene nanoplatelets (GNPs) in polylactic acid (PLA)/polystyrene (PS) co-continuous polymer blends. Although GNPs in thermal equilibrium prefer the PS phase, we were able to kinetically trap GNPs at the interface of polymer blends via control of melt-compounding sequences, mixing times and shear rates. Utilizing morphological, rheological, and electrical measurements, we verified graphene localization and the suppression of coarsening in co-continuous polymer blends during annealing. When GNPs were premixed with the thermodynamically less-favorable PLA phase before mixing with the PS phase, GNPs can be kinetically trapped at the interface during melt compounding. Moreover, we show that a shorter melt-compounding time gives rise to a higher GNP interfacial coverage and a more effective morphology stabilization effect. Blends with as low as 0.5 wt % GNPs with only 30 s of melt compounding have a room-temperature conductivity of ∼10-6 S/cm, which is larger than blends with longer melt-compounding times and potentially useful for antistatic materials. The in-depth study on the kinetics of graphene localization in our work provides a general guideline for the kinetic control of the localization of platelike nanofillers in polymer blends. Our study also demonstrates a facile method for manufacturing conductive polymer blends with low percolation thresholds.

Incoherent Pathways of Charge Separation in Organic and Hybrid Solar Cells.

In this work, we investigate the exciton dissociation dynamics occurring at the donor:acceptor interface in organic and hybrid blends employed in the realization of photovoltaic cells. Fundamental differences in the charge separation process are studied with the organic semiconductor polymer poly(3-hexylthiophene) (P3HT) and either [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) or titanium dioxide (TiO2) acting as the acceptor. By using ultrafast broad-band transient absorption spectroscopy with few-fs temporal resolution, we observe that in both cases the incoherent formation of free charges dominates the charge generation process. From the optical response of the polymer and by tracking the excited-state absorption, we extract pivotal similarities in the incoherent energy pathways that follow the impulsive excitation. On time scales shorter than 200 fs, we observe that the two acceptors display similar dynamics in the exciton delocalization. Significant differences arise only on longer time scales with only an impact on the overall photocarrier generation efficiency.

Tunable Electrical Conductivity of Carbon-Black-Filled Ternary Polymer Blends by Constructing a Hierarchical Structure.

A type of hierarchical structured composite composed of a minor thermoplastic polyurethane (TPU) phase spreading at the interface of two major phases polyoxymethylene/polyamide copolymer (POM/COPA) and carbon black (CB) particles selectively localized at the TPU/COPA interface of the tri-continuous blends was fabricated by melt compounding. The hierarchical structure was designed according to predictions and verified by a combination of electron microscopy and solvent extraction technique. The hierarchical structured composites show the dramatically decreased percolation threshold, a reduction of 60% compared to those without TPU where CB is selectively distributed in the COPA phase. The effects of CB contents and TPU on the phase morphology of POM/COPA were investigated, showing the occurrence of the POM/COPA phase inversion from a sea-island to a co-continuous structure beyond the percolation threshold of CB in the presence of TPU. The mechanism for the formation of conductive network is construction of CB network at the TPU/COPA interface of tri-continuous POM/COPA/TPU blends and double percolation effect.

Tailor-Made Dispersion and Distribution of Stereocomplex Crystallites in Poly(l-lactide)/Elastomer Blends toward Largely Enhanced Crystallization Rate and Impact Toughness.

Stereocomplex (SC) crystallites, formed between poly(l-lactide) (PLLA) and poly(d-lactide), exhibit great potential to substantially enhance crystallization rate of PLLA-based materials as an eco-friendly nucleating agent. However, the nucleation efficiency of the SC crystallites is still far below an expected level, mostly on account of their strong aggregation tendency in PLLA/PDLA melts. Herein, taking PLLA/poly(ethylene-methyl acrylate-glycidyl methacrylate) (E-MA-GMA) blends as an example, we report a unique and facile strategy to control the dispersion and distribution of SC crystallites within the PLLA matrix by using elastomeric E-MA-GMA as carrier for the incorporation of PDLA. To do this, PDLA was first blended with E-MA-GMA or chemically grafted onto the E-MA-GMA. During subsequent melt-blending of PLLA and the E-MA-GMA/PDLA master batch, the PDLA chain clusters predispersed in the E-MA-GMA phase can gradually migrate into PLLA matrix and then collaborate with the matrix chains to form large amounts of tiny and well-dispersed SC crystallites. Compared with the SC-crystallite agglomerates formed by the direct melt-blending of PLLA and PDLA components, such tiny SC crystallites are much more effective in accelerating PLLA matrix crystallization. More interestingly, when PDLA chains are grafted onto the EMA-GMA, the formed SC crystallites tend to preferentially distribute at the blend interface and thus induce not only optimal nucleation efficiency but also superior impact toughness because these interface-localized SC crystallites can also serve as bridges to enhance interface adhesion. This work could open a new avenue in designing heat-resistant and supertough PLLA blends via controllable construction of SC crystallites.