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A two-step method to modify trans-1,4-polyisoprene (TPI): first, TPI is crosslinked by γ-ray; then, the crosslinked TPI is grafted with n-dodecanethiol by thiol–ene click chemistry. The modified TPI shows high elasticity.

The interplay between crosslinks and crystals is critical for the mechanical properties of Eucommia ulmoides gum (EUG). It was shown here that the hysteresis loss of vulcanized EUG depends significantly on strain-induced crystallization/melting.

In the present work, we report a facile approach to fabricate porous long-chain polyamides (LCPAs) through a non-conventional evaporation induced phase separation. Taking advantage of their amphiphilic nature, LCPAs can be dissolved by a mixture of a polar and a non-polar solvent. The sequential evaporation of solvents leads to the rapid formation of homogeneous pores within 1 minute. Also, it demonstrates that this approach can be applied to other long-chain polycondensates. Our finding provides a new insight to the rapid and coagulating-bath-free fabrication of porous materials.

The polymorphic transition of trans−1,4−polyisoprene (TPI) during stretching was investigated by in−situ wide−angle X−ray diffraction and Fourier transform infrared spectroscopy. The influences of the initial structure, stretching temperature, and strain rate on the contents of different crystal modifications (α, β) were explored. The results confirm that the α−β transition occurs during stretching of TPI that only contains α crystal (α-TPI). When the stress is relaxed, the β crystal formed during stretching remains, which indicates that the transition is irreversible. On the other hand, stretching of TPI that only contains β crystal (β-TPI) results in orientated β crystal. No β−α transition occurs during stretching. The different structures of stretched α−TPI and β-TPI exclude the previously proposed “melting−recrystallization mechanism”. The α−β transition depends significantly on temperature and strain rate, indicating the transition is governed both by thermodynamics and kinetics. Our results support a solid−solid transition mechanism rather than a melting−recrystallization mechanism. The irreversible nature of the transition is attributed to the metastability of the β phase in the unstretched state. Different from the “β phases” that appear in polymers with stress-induced reversible transitions, e.g. poly(butylene terephthalate) and poly(butylene succinate), the stability of β phase in TPI is high that can be long-lived. The strain rate dependence of α−β transition hinders the determination of critical stress for the transition. It further indicates that the local stress within the sample is more heterogeneous at higher strain rates.

Unformatted post-print version of the accepted article Solid-solid transitions in poly (hexamethylene carbonate) (PC6) and poly (octamethylene carbonate) (PC8), denoted δ to α transition, have been investigated, using self-nucleation and Successive Self-nucleation and Annealing (SSA) technique. The SSA protocol was performed in-situ for thermal (differential scanning calorimetry (DSC)), structural (Wide-angle X-ray Scattering (WAXS)), and conformational (Fourier-transformed Infrared Spectroscopy (FT-IR)) characterization. The final heating after SSA fractionation displayed an enhanced (compared to a standard second DSC heating scan) endothermic and unfractionated peak signal at low temperatures corresponding to the δ to α transition. The improved (i.e., higher enthalpy and temperature than in other crystallization conditions) δ to α transition signal is produced by annealing the thickest lamellae made up by α and β phase crystals after SSA treatment. As thicker lamellae are annealed, more significant changes are produced in the δ to α transition, demonstrating the transition dependence on crystal stability, thus, on the crystallization conditions. The ability of SSA to significantly enhance the observed solid-solid transitions makes it an ideal tool to detect and study this type of transitions. In-situ WAXS reveals that the δ to α transition corresponds to a change in the unit cell dimensions, evidenced by an increase in the d-spacing. This implies a more efficient chain packing in the crystal, for both samples, in the δ phase (lower d-spacing at low temperatures) than in the α phase (higher d-spacing at high temperatures). The chain packing differences are explained through in-situ FT-IR measurements that show the transition from ordered (δ phase) to disordered (α phase) methylene chain conformations. We would like to acknowledge financial support provided by the National Key R&D Program of China (2017YFE0117800) and the National Natural Science Foundation of China (51820105005, 21922308, and 52050410327). We also acknowledge financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 778092. This work has also received funding from MINECO through project MAT2017-83014-C2-1-P and from the Basque Government through grant IT1309-19. R.A.P.-C is supported by the China Postdoctoral Science Foundation (2020M670462). G.L. is grateful to the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Y201908). We also thank the BSRF (beamline 1W2A) for providing beamtime.

Unformatted post-print version of the accepted article Poly (hexamethylene carbonate) (PC6) and poly (octamethylene carbonate) (PC8) were studied under different crystallization conditions. Using differential scanning calorimetry (DSC), a new solid-solid transition, denoted α to δ transition, was detected at low temperatures (

Unformatted post-print version of the accepted article Crystallization of polymeric materials under nanoscopic confinement is highly relevant for nanotechnology applications. When a polymer is confined within rigid nanoporous anodic aluminum oxide (AAO) templates, the crystallization behavior experiences dramatic changes as the pore size is reduced, including nucleation mechanism, crystal orientation, crystallization kinetics, and polymorphic transition, etc. As an experimental prerequisite, exhaustive cleaning procedures after infiltrations of polymers in AAO pores must be performed to ensure producing an ensemble of isolated polymer-filled nanopores. Layers of residual polymers on the AAO surface percolate nanopores and lead to the so-called “fractionated crystallization”, i.e., multiple crystallization peaks during cooling. As the density of isolated nanopores in a typical AAO template exceeds the density of heterogeneities in bulk polymers, the majority of nanopores will be heterogeneity-free. This means that the nucleation will proceed by surface or homogeneous nucleation. As a consequence, a very large supercooling is necessary for crystallization, and its kinetics is reduced to a first-order process that is dominated by nucleation. Self-nucleation is a powerful method to exponentially increase nucleation density. However, when the diameter of the nanopores is lower than a critical value, confinement prevents the possibility to self-nucleate the material. Because of the anisotropic nature of AAO pores, polymer crystals inside AAO also exhibit anisotropy, which is determined by thermodynamic stability and kinetic selection rules. For low molecular weight poly(ethylene oxide) (PEO) with extended chain crystals, the orientation of polymer crystals changes from the “chain perpendicular to” to “chain parallel to” AAO pore axis, when the diameter of AAO decreases to the contour length of the PEO, indicating the effect of thermodynamic stability. When the thermodynamic requirement is satisfied, the orientation is determined by kinetics including crystal growth, nucleation and crystal growth rate. An orientation diagram has been established for PEO/AAO system, considering the cooling condition and pore size. The interfacial polymer layer has different physical properties as compared to the bulk. In poly(L-lactic acid), the relationship between the segmental mobility of the interfacial layer and crystallization rate is established. For the investigation of polymorphic transition of poly(butane-1), the results indicate that a 12 nm interfacial layer hinders the transition of Form II to Form I. Block and random copolymers have also been infiltrated into AAO nanopores, and their crystallization behavior is analogously affected as pore size is reduced. This work was supported by the National Key R&D Program of China (Grant No. 2017YFE0117800) and the National Natural Science Foundation of China (Grant Nos. 21873109, 51820105005, and 21922308). We also acknowledge the financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 778092. A.J.M. acknowledges funding from MINECO, Grant No. MAT2017-83014-C2-1-P, and from the Basque Government through Grant No. IT1309-19. G.L. is grateful to the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. Y201908).

ω-Alkenylmethyldichlorosilane-assisted propylene polymerization for the synthesis of long-chain-branched polypropylene (LCB-PP) was applied in a liquid bulk polymerization process to verify its ind...

Unformatted post-print version of the accepted article The inclusion of polymer-grafted nanoparticles (PGNPs) can impart various functional properties to polymer nanocomposites (PNCs). For semicrystalline polymers, we can control the spatial dispersion of PGNPs and presumably use it to modulate the nucleation rate of the polymer. In this work, the correlation between the dispersion quality of poly(ethylene glycol) (PEG) grafted silica (PEG-g-SiO2) nanoparticles and the crystallization ability of poly(ethylene oxide) (PEO) nanocomposites is systematically investigated by varying the grafting density (σ, chains/nm2) and the value of P/N (P: molecular weight of matrix chains, N: molecular weight of grafted chains). The variation of PEG-g-SiO2 dispersion state was studied by morphological characterization and small-angle X-ray scattering (SAXS). It was found that, in contrast to the unmodified SiO2 and poly(methyl methacrylate) grafted silica (PMMA-g-SiO2), PEG-g-SiO2 (high σ and low P/N) can increase the nucleation rate of PEO even under conditions where they are well dispersed in the PEO matrix. Evidently, the nature of the graft, i.e., amorphous PMMA vs. crystallizable PEO, has profound consequences in this context, a novel result that has not been anticipated based on previous work. NP aggregation occurs at higher P/N values and limits the effectiveness of the grafted PEG on the crystallization ability of PEO nanocomposites. Based on differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM) characterization, we deduced that the increased nucleation density at high σ and low P/N has a strong impact on accelerating the overall crystallization of PEO nanocomposites. This project is supported by the Ministry of Science and Technology of China (2017YFE0117800) and the National Natural Science Foundation of China (21574141). We would like to thank the financial support provided by the BIODEST project; this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778092. The authors thank Prof. Yongfen Men (CIAC) for providing the SAXS beam time and helps during experiments. The discussion of TEM data with Andrew M. Jimenez (Columbia University, New York, NY) is gratefully acknowledged. We also thank B. Guan, J. L. Yue and K. A. Liu for help in cryo-TEM experiments.

The temperature dependence of the rheological properties of poly(ether-b-amide) (PEBA) segmented copolymer under oscillatory shear flow has been investigated. The magnitude of the dynamic storage modulus is affected by the physical microphase separation and irreversible crosslinking network, with the latter spontaneously forming between the polyamide segments and becoming the dominant factor in determining the microstructural evolution at temperatures well above the melting point of PEBA. From the rheological results, the initial temperature of the rheological properties dominated by the microphase separation and crosslinking (Tcross) structures were determined, respectively. Based on the two obtained temperatures, the microstructure evolution upon the heating can be separated into the ternary microstructure domains: homogenous (temperature below ), microphase separation dominating (between and Tcross), and crosslinking dominating domains (above Tcross). When the PEBA is heated to above Tcross, the content of crosslinking network increases with time and temperature, leading to an irreversible and non-negligible influence on the rheological, crystallization, and mechanical properties. A more pronounced strain-hardening phenomenon during the uniaxial stretching is observed for the sample with a higher content of crosslinking network.

HighlightsThe proposed method detected thrips and whitefly more accurately than previous methods.The proposed method demonstrated good robustness to illumination reflections and different pest densities.Small pest detection was improved by adding large-scale feature maps and more residual units to a shallow network.Machine vision and deep learning created an end-to-end model to detect small pests on sticky traps in field conditions.Abstract. Pest detection is the basis of precise control in vegetable greenhouses. To improve the detection accuracy and robustness for two common small pests (whitefly and thrips) in greenhouses, this study proposes a novel small object detection approach based on the YOLOv4 model. Yellow sticky trap (YST) images at the original resolution (2560 × 1920 pixels) were collected using pest monitoring equipment in a greenhouse. The images were then cropped and labeled to create sub-images (416 × 416 pixels) to construct an experimental dataset. The labeled images used in this study (900 training, 100 validation, and 200 test) are available for comparative studies. To enhance the model’s ability to detect small pests, the feature map at the 8-fold downsampling layer in the backbone network was merged with the feature map at the 4-fold downsampling layer to generate a new layer and output a feature map with a size of 104 × 104 pixels. Furthermore, the residual units in the first two residual blocks were enlarged by four times to extract more shallow image features and the location information of target pests to withstand image degradation in the field. The experimental results showed that the mean average precision (mAP) for detection of whitefly and thrips using the proposed approach was improved by 8.2% and 3.4% compared with the YOLOv3 and YOLOv4 models, respectively. The detection performance slightly decreased as the pest densities increased in the YST image, but the mAP value was still 92.7% in the high-density dataset, which indicates that the proposed model has good robustness over a range of pest densities. Compared with previous similar studies, the proposed method has better potential to monitor whitefly and thrips using YSTs in field conditions. Keywords: Deep learning, Greenhouse pest management, Image processing, Pest detection, Small object, YOLOv4.

Stimulus-responsive polymers containing dynamic bonds enable fascinating properties of self-healing, recycling and reprocessing due to enhanced relaxation of polymer chain/network with labile linkages. Here, we study the structure and properties of a new type of thermoplastic polyurethanes (TPUs) with trapped dynamic covalent bonds in the hard-phase domain and report the frustrated relaxation of TPUs containing weak dynamic bond and π-π interaction in hard segments. As detected by rheometry, the aromatic TPUs with alkyl disulfide in the hard segments possess the maximum network relaxation time in contrast to those without dynamic bonds and alicyclic TPUs. In situ FTIR and small-angle scattering results reveal that the alkyl disulfide facilitates stronger intermolecular interaction and more stable micro-phase morphology in π-π interaction based aromatic TPUs. Molecular dynamics simulation for pure hard segments of model molecules verify that the presence of disulfide bonds leads to stronger π-π stacking of aromatic rings due to both enhanced assembling thermodynamics and kinetics. The enhanced π-π packing and micro-phase structure in TPUs further kinetically immobilize the dynamic bond. This kinetically interlocking between the weak dynamic bonds and strong molecular interaction in hard segments leads to much slower network relaxation of TPU. This work provides a new insight in tuning the network relaxation and heat resistance as well as molecular self-assembly in stimulus-responsive dynamic polymers by both molecular design and micro-phase control toward the functional applications of advanced materials.

The determination of intrinsic chain stiffness of conjugated polymers is challenging, in particular, for scattering techniques because of their strong light absorption and structural instability du...

Purpose Cancer tissue-specific and nuclei-targeted drug delivery is ideal for the delivery of chemotherapy. However, it has only been achieved in in vitro studies mainly due to low efficiency in vivo. In this study, we aimed to establish an efficient dual-targeted system that targets liver cancer tissue as well as the nuclei of cancer cells in vivo. Methods We first synthesized TAT peptide (TATp)-mesoporous silica nanoparticle (MSN) complex (TATp-MSN) and generated liposomes that carried liver cancer-specific aptamer TLS11a (TLS11a-LB). We then generated the drug TLS11a-LB@TATp-MSN/doxorubicin (DOX) by mixing TLS11a-LB and DOX-loaded TATp-MSN. After physical and chemical characterization of the nanoparticles, DOX release from these formulations was evaluated at pH 5.0 and 7.4. Furthermore, we also evaluated nuclear localization and cytotoxicity of the drug in H22 cells in vitro and investigated the liver cancer targeting and antitumor activities of the nano-drug in vivo using a H22 tumor-bearing mice model. Results TLS11a-LB@TATp-MSN/DOX and its controls were confirmed as nano-drugs (

Unformatted post-print version of the accepted article There has been considerable interest in the nucleation and crystallization of polymers in the presence of nanoparticles (NPs, or nanofillers in general, NFs). Most of the extensive work in this area has focused on anisotropic, non-Brownian NFs (e.g., clay sheets, carbon nanotubes) whose spatial dispersion state in these nanocomposites is controlled by the process by which they are formed. While NF spatial dispersion is thus generally poor, or poorly characterized, in many works, thermodynamic handles that can be used to control NF dispersion state in the polymer melt include (a) favorable interactions between the polymer chains and the bare NP surfaces, or (b) the density and length of the chains, with the same chemistry as the matrix, grafted to the NP surface. These relatively large NFs merely act as immovable objects that affect the kinetics of nucleation by providing heterogeneous sites, and the crystallization rate by confining the polymer in the melt state. The dispersion state of the NFs can dramatically 2 affect the nucleation and crystallization of the matrix, but in most cases reported, the NFs increase nucleation efficiency relative to the neat polymer. At higher NF loadings, the effect of polymer confinement by the NFs dominates, leading to a decrease in crystal growth rates. In this review, we first describe the most important lessons learned from these commonly studied systems and then use this knowledge to understand the results obtained when small, mobile spherical NPs (typically smaller than 100 nm in size) are used as the nanofillers. The role of NP mobility, which provides for dynamic confinement of the polymer melt, on the kinetics of polymer crystallization (nucleation, growth, and overall crystallization) and how this behavior is mostly consistent with the case of immobile NF is a second important focus of our review. In addition to the role of NFs on crystallization kinetics, we discuss recently reported nanoparticle ordering phenomena, i.e., how the crystallization of polymers under appropriate conditions can move and organize small spherical NPs within the amorphous regions of the semicrystalline morphology. Such phenomena are clearly not observed for large NFs and hence provide a point of departure from past work in this well-traveled area. This work was supported by grants DE-SC0018182, DE-SC0018135, and DE-SC0018111 funded by the U.S Department of Energy, Office of Science. We would like to thank the financial support provided by National Key R&D Program of China (Grant No. 2017YFE0117800) and the National Natural Science Foundation of China (Grant Nos. 21574141, 51820105005, and 52050410327). We also acknowledge the financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 778092. A.J.M. acknowledges funding from MINECO, project MAT2017-83014-C2-1-P, and from Basque Government through grant IT1309-19. A.A.K. acknowledges funding from the Gates Millennium Scholars program under Grant No. OOP1202023 from the Bill & Melinda Gates Foundation. R.A.P.-C is supported by the China Postdoctoral Science Foundation (Grant No. 2020M670462).

The Theological property evolution of polyamide 1012 (PA1012) in the isothermal process in molten state has been investigated. The results show that the viscosity increases and crosslinking reaction occurs simultaneously together with the increase of temperature, thus causing the variation of storage modulus (G′) and loss modulus (G″) in the repeated frequency sweeps with residual time. This research has pointed out that the superposition is valid for monitoring the complex behavior composed of the viscosity increasing and crosslink occurring process by tracing the variation behavior of the crossover points of G’ and G” with time, revealing the same time-temperature dependence of the two reactions in the isothermal process. A normalized master curve has been proposed to describe the melt behavior at a given temperature.

The objective of this study was to clarify the cell structure variation of poly(ether-mb-amide) (PEBA) copolymer with the chemi-crystallization induced via thermal treatment at melt state. The ther...

This work describes the successful melt infiltration of poly(butylene succinate) (PBS) and poly(butylene adipate) (PBA) within 70 nm diameter anodic aluminum oxide (AAO) templates. The infiltrated samples were characterized by SEM, Raman, and FTIR spectroscopy. The crystallization behaviors and crystalline structures of both polymers, bulk and confined, were analyzed by differential scanning calorimetry (DSC) and grazing incidence wide angle X-ray scattering (GIWAXS). DSC revealed that a change in the nucleation process occurred from heterogeneous nucleation for bulk samples to homogeneous nucleation for infiltrated PBA and to surface-induced nucleation for infiltrated PBS. GIWAXS results indicate that PBS nanofibers crystallize in the α-phase, as well as their bulk samples. However, PBA nanofibers crystallize just in the β-phase, whereas PBA bulk samples crystallize in a mixture of α- and β-phases. The crystal orientation within the pores was determined, and differences between PBS and PBA were also found. Finally, broadband dielectric spectroscopy was applied to study the segmental dynamics for bulk and infiltrated samples. The glass temperature was found to significantly decrease in the PBS case upon infiltration, while that of PBA remained unchanged. These differences were correlated with the higher affinity of PBS to the AAO walls than PBA, in accordance with their nucleation behavior (surface-induced versus homogeneous nucleation, respectively)., POLYMAT and ICTP-CSIC Institutions acknowledge financial support from the Spanish Ministry of Science, Innovation, and Universities (MAT2017-83014-C2-1-P and MAT2017- 83014-C2-2-P). M.S. gratefully acknowledges the award of a PhD fellowship by POLYMAT Basque Center for Macromolecular Design and Engineering. J.M. acknowledges support from the Provincial Council of Gipuzkoa under the program Fellow Gipuzkoa and “Fomento San Sebastián” in the framework program “Retorno del Talento Local” Donostia up! 2016. G.L, D.W., and A.J.M acknowledge the support from the National Natural Science Foundation of China (51820105005, 21873109) and National Key R&D Program of China (2017YFE0117800). G.L. acknowledges the support from the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2015026). This work has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska- Curie grant agreement no. 778092. The UPV/EHU team gratefully acknowledges the financial contribution of the Basque Government through grants IT1309-19 and IT1175- 19.

We studied the crystallization of nearly “homogeneous” polyethylene glycol (PEG) networks prepared by end-crosslinking of tetra-armed PEG. The influence of stretching ratio and strand length on the melting and crystallization temperature was investigated. The relation of melting temperature and elongation ratio verifies the thermodynamic theories of strain-induced polymer crystallization.

The fabrication of a single polymer network that exhibits a good reversible two-way shape memory effect (2W-SME), can be formed into arbitrarily complex three-dimensional (3D) shapes, and is recyclable remains a challenge. Herein, we design and fabricate poly(thiourethane) (PTU) networks with an excellent thermadapt reversible 2W-SME, arbitrary reconfigurability, and good recyclability via the synergistic effects of multiple dynamic covalent bonds (i.e., ester, urethane, and thiourethane bonds). The PTU samples with good mechanical performance simultaneously demonstrate a maximum tensile stress of 29.7 ± 1.1 MPa and a high strain of 474.8 ± 7.5%. In addition, the fraction of reversible strain of the PTU with 20 wt % hard segment reaches 22.4% during the reversible 2W-SME, where the fraction of reversible strain is enhanced by self-nucleated crystallization of the PTU. A sample with arbitrarily complex permanent 3D shapes can be realized via the solid-state plasticity, and that sample also exhibits excellent reversible 2W-SME. A smart light-responsive actuator with a double control switch is fabricated using a reversible two-way shape memory PTU/MXene film. In addition, the PTU networks are de-cross-linked by alcohol solvolysis, enabling the recovery of monomers and the realization of recyclability. Therefore, the present study involving the design and fabrication of a PTU network for potential applications in intelligent actuators and multifunctional shape-shifting devices provides a new strategy for the development of thermadapt reversible two-way shape memory polymers.

In the present work, crystallization of a soluble nucleator N, N′, N″-tricyclohexyl-1,3,5-benzenetricarboxylamide (TMC-328) in a poly(l-lactic acid) (PLLA) matrix has been studied at different temperatures. Based on the change in solubility with temperature, different levels of supersaturation of TMC-328 in a PLLA matrix can be obtained. This nucleator presents a fibrous structure produced via self-assembling and develops into an interconnected network when the temperature is lowered. The TMC-328 crystal nuclei density is quantified via optical microscopy, using the average distance of the adjacent fibrillar structure, which shows a steady decrease with the decrease in temperature. The crystallization rates of TMC-328 were assessed through rheological measurements of network formation. Both fibrils’ density and crystallization kinetics display a power law dependence on supersaturation. For the first time, the solid–melt interfacial energy, the size of the critical nucleus, and the number of molecules making up the critical nucleus of the nucleator TMC-328 in the PLLA matrix have been determined by adopting the classical nucleation theory. The subsequent crystallization of PLLA induced by this nucleator was investigated as a function of the fibrils’ spatial density. The crystallization rate of PLLA is enhanced with the increase in the TMC-328 fibrils’ density because of the availability of a larger nucleating surface. The self-assembled fibril of TMC-328 can serve as shish to form a hybrid shish-kebab structure after the crystallization of PLLA, regardless of the number of nucleation sites., The equilibrium solubility of a nucleating agent (TMC-328) in poly(l-lactide) melt is determined as a function of temperature. Crystallization experiments at different supersaturations, above the melting point of the polymer, are then performed. It is shown that both the spatial density of fibrillar crystals and the overall crystallization rate of TMC-328 are strong functions of the degree of supersaturation. The results are in agreement with the classical nucleation theory of small molecular crystals.

Unformatted post-print version of the accepted article The melt memory effect is well-known in polymer crystallization. It is caused by self-nuclei that persist above the melting temperature. The origin and physical nature of self-nuclei are still under debate. In this work, we studied the effect of confinement on the self-nucleation behavior of two typical semicrystalline polymers: poly(ε-caprolactone) (PCL) and poly(butylene succinate) (PBS) using anodic aluminum oxide (AAO) templates. The density of AAO nanopores covers a range of 1011 ~ 1013 cm-3. Narrowing of the self-nucleation region (Domain II) with a decrease of AAO diameter was observed for both infiltrated PCL and PBS, indicating the suppression of the self-nucleation effect. When the diameter of AAO is below 60 nm, Domain II vanished. Further analysis indicated that Domain IIa (melt memory region) vanished first, followed by Domain IIb (self-seeding region). The results provide a method of estimating the self-nuclei density of different polymers at different temperatures. This work was supported by the National Natural Science Foundation of China (21873109, 51820105005, and 21922308) and the National Key R&D Program of China (2017YFE0117800). We would also like to acknowledge the financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778092. G.L. is grateful to the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Y201908).

The objective of the present work is to verify the competitive effect between the heterogeneous and gas-diffusion cell nucleation in foaming of polystyrene/poly(methyl methacrylate) (PS/PMMA) blends with PS or PMMA as the dispersed phase after structural evolution driven by phase separation. Four PS/PMMA blends were thermally annealed for various times. Scanning electron microscopy (SEM) was employed to study the phase morphology. The domain size and domain density were thus obtained, and the interface area was then calculated. The samples were foamed via a batch foaming process, and SEM was used to study the cell structure. It was found that with thermal annealing, the phase domain size was increased, the domain density was decreased, and the interface area was decreased. For PS20/PMMA80 and PS30/PMMA70, the cell size was increased and cell density was decreased, while for PS80/PMMA20 and PS70/PMMA30, the cell size was decreased and cell density was increased. The expansion ratio was decreased for all of...

While a relatively complete understanding of the nucleation and orientation of polymers under confinement in one-dimensional nanochannels has been achieved, crystallization kinetics investigation of confined polymers is still rare. In this work, we investigated the crystallization kinetics of poly(ethylene oxide) confined in anodic alumina oxide templates with different pore sizes using in situ wide-angle X-ray scattering (WAXS). The crystallization kinetics results were fitted with the Avrami equation. The Avrami index was determined by both "isothermal step crystallization" and in situ WAXS. The crystallization process of polymers under one-dimensional nanopore confinement was simulated by a "one-dimensional lattice model". Based on this model, it is shown that homogeneous nucleation with the simultaneous growth of multiple crystal planes with drastically different growth rates could result in Avrami indexes lower than 1.