CHINESE JOURNAL OF POLYMER SCIENCE
·
2019
·Vol. 38
·期 3
·298-310
·
IF 2.804
Feng Cong-Shu,Chen Yun,Shao Jun,Li Gao,Hou Hao-Qing
In this study, the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide) (PDLA- b -PBS- b -PDLA) triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized, and the crystallization behaviors of the PDLA and PBS blocks are investigated. Although both the crystallization behaviors of PBS and PDLA blocks depend on composition, they exhibit different variations. For the PDLA block, its crystallization behaviors are mainly influenced by temperature and block length. The crystallization signals of PDLA block appear in the B-D 2–2 specimen, and these signals get enhanced with PDLA block length. The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100 °C. Crystallizing at higher temperature, the crystallization rates increase at first and then decrease with block length. The crystallization rates decrease as elevating the crystallization temperature. The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures. For the PBS block, its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block. The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized, while the crystallization rates of the PBS block exhibit unique component dependence, and the highest rate is observed in the B-D 2–2 specimen. The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature. This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES B-BIOINTERFACES
·
2018
·
IF 3.997
Bowen Yu,Lu Meng,Sirui Fu,Zhiyu Zhao,Yuhang Liu,Ke Wang,Qiang Fu
The applications of Polylactide (PLA) microspheres in biomedical areas are greatly determined by the size, morphology and internal structure. Taking advantage of the formation of stereocomplex (SC) crystallites between poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), we propose a facile strategy to prepare PLA microspheres with tunable morphology and crystalline structure by compounding PLLA and PDLA. With increasing PDLA content, the crystallinity of SC-PLA rose gradually until the ratio of PLLA and PDLA reached 1:1 and then fell. Correspondingly, the morphology of the microspheres were varied (smooth, porous, golf-ball like, guava like) and higher crystallinity of SC-PLA would lead to a more coarse and porous structure. Finally, three typical kinds of Rifampicin-loaded microspheres with different ratio of PLLA and PDLA (7:3, 3:7, 10:0, sorted by porosity from high to low) were prepared and the release behavior was compared. At 30 h, the cumulative release of 7:3, 3:7 and 10:0 microspheres were 32.6%, 17.8% and 6.0% respectively, indicating that the release profiles were generally determined by the porosity of the microspheres. Our findings not only provide a new strategy to prepare PLA microspheres with controllable morphology but offer additional possibilities for the applications of SC-PLA products in biomedical area.
研究领域:
生物医学工程
·
药学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 47
·20812-20822
·
IF 3.288
Yao Chen,Ping Ning,Rongrong Miao,Yuzhen Shi,Liang He,Qingqing Guan
Carbon materials show great potential in catalytic applications, due to their advantages of wide raw material sources, stable chemical properties, and large specific surface area. In this paper, N-doped biochar was prepared from Pennisetum giganteum for supporting PdLa bimetallic nanoparticles to achieve efficient conversion of acetylene. The results showed that the conversion and ethylene selectivity of the Pd0.25La0.25/N-pgBC bimetallic catalyst could reach 100% and 94.2%, respectively. From the characterization results, it could be inferred that the electron transfer from lanthanum to palladium can weaken the ethylene adsorption onto the negatively charged Pd sites and thus improve the selectivity of Pd0.25La0.25/N-pgBC. It is noted that the bimetallic PdLa/N-pgBC catalyst showed strong component dependence, which may be caused by the difference in electronic or geometric modification caused by different metal ratios. This work has shown that the active site separation effect formed by doping inert metals is of great significance to the whole catalytic field.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2017
·
IF 6.035
Zhu Xiong,Yun Zhong,Haibo Lin,Fu Liu,Tiantian Li,Jinglong Li
In this work, a feasible and efficient approach was developed to produce Poly(lactic acid (PLA) ultrafiltration membrane with both high permeability and high rejection simultaneously. Poly(L-lactic acid)/Poly(D-lactic acid) (PDLA/PLLA) stereocomplex crystallites were thought to play the critical role different from the traditional pore forming agents or hydrophilic modification. The membrane morphology of the stereocomplex PDLA/PLLA membrane with high porosity and thin skin layer was observed by SEM. The addition of PDLA resulted in the thermodynamic enhancement for phase separation of PLLA casting solution as demonstrated by a rotational rheometer. The PDLA/PLLA stereocomplex crystallization behavior was investigated by DSC and XRD . With increasing the stereocomplex crystallites, the water permeability of PLA membrane significantly increased from ~482 L/m 2 ·h to ~3325 L/m 2 h, while with small loss in degree of rejection. Furthermore, the stereocomplex PLA membrane demonstrated the excellent separation efficiency for nano-TiO 2 and ink dispersion. Besides, the stereocomplex PLA membrane exhibited outstanding anti-protein fouling properties through the static and dynamic BSA antifouling tests. All results demonstrated that the stereocomplexation can effectively tune the pore size evolution and control the permeability, selectivity and fouling resistance.
研究领域:
材料科学
·
膜技术
·
高分子化学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2021
·
IF 4.089
Wenyuan Xie,Chenguang Jiang,Xing Yu,Xinyu Shi,Shubin Wang,Yu Sun,Ming Yin,Defeng Wu
Biodegradable polymersomes that can potentially be employed in drug delivery systems were fabricated by blending poly(l-lactide)-b-poly(ethylene glycol)-b-poly(l-lactide) (PLLA-PEG-PLLA) and poly(d-lactide)-b-poly(ethylene glycol)-b-poly(d-lactide) (PDLA-PEG-PDLA) block copolymers in a weight ratio of 1:1 in an aqueous solution. A series of amphiphilic PLLA-PEG-PLLA and PDLA-PEG-PDLA triblock copolymers were synthesized with different hydrophobic chain lengths through ring-opening polymerization. The self-assembly of pure PLLA-PEG-PLLA and an equimolar mixture of enantiomers of PLLA-PEG-PLLA and PDLA-PEG-PDLA was investigated by transmission electron microscopy, X-ray diffraction, and dynamic light scattering. Various nanostructures including spherical micelles, worm-like micelles, and vesicles were obtained by controlling the hydrophobic chain length and the incubation temperature. In the pure PLLA-PEG-PLLA systems, the hydrophobic–hydrophilic balance dominated the self-assembled morphologies. In equimolar enantiomer mixtures, self-assembled morphologies were greatly affected by the formation of the PLLA-PDLA stereocomplex (SC). There was an inverse correlation between the SC crystallinity and the curvature of the self-assembled structures─the higher the SC content, the smaller the curvature. This rule was not applicable when the SC content was too high (≳50%), which produced spherical micelles as the main nanostructures. Since the SC-induced self-assembly could be controlled by changing the incubation temperature, the polymersomes can potentially be used in many applications, such as nanoreactors and nanovehicles.
研究领域:
材料科学
·
药物递送系统
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Yunping Ma,Qianzuo Liu,Binqi He,Sifan Sun,Maiyong Zhu,Ting Zhang,Tie Li
The development of efficient electrochemical catalysts capable of highly sensitive detection of small molecules poses a significant challenge. Recent advancements in two-dimensional materials, such as palladium metallene (Pdene), have shown promising application prospects in overcoming these challenges. Nevertheless, critical issues such as optimizing their electrochemical activity and enhancing sensitivity and selectivity for molecular detection remain unresolved. In this study, we synthesized lanthanum-doped palladium bimetallenes (PdLa BMLs), which serve as high-performance catalysts for constructing flexible electrochemical sensors with highly sensitive and selective responses to isopropanol. This improvement is attributed to the nonhomogeneous crystal structure of the Pdene substrate, which, enhanced by La doping, optimizes the electronic structure and active sites, resulting in increased adsorption capacity (evidenced by a significant upward shift in the d-band center) and reduced reaction energy barriers in the isopropanol oxidation reaction (IOR). Our findings not only demonstrate that La doping enhances the activity of metallene active sites, thereby improving catalytic efficiency, but also broaden the applications of metallenes in electrocatalytic sensors for detecting small molecules relevant to health and food industries.
研究领域:
材料科学
·
电化学
·
纳米技术
·
传感器与生物传感器
·
催化
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Omega
·
2019
·
IF 2.584
Yuanping Jiang,Cong Yan,Dawei Shi,Zhengying Liu,Mingbo Yang
The inadequate rheological properties limit the film blowing process of biodegradable polylactic acid (PLA), thus hindering its potential application in environmentally friendly packaging films and mulch films. Herein, biodegradable polyethylene glycol (PEG) and d-lactide were used to synthesize three kinds of poly-d-lactic acid (PDLA)-b-PEG-b-PDLA (DPD) triblock copolymers, and their effects on stereocomplex (sc) structure formation and rheological properties of the composites were studied. The results showed that the poly l-lactic acid (PLLA)/DPD4k sample introduced the highest sc content, storage modulus, and complex viscosity value compared with PLLA/DPD2k and PLLA/DPD10k at the same loading condition, indicating that the PEG4k chains can better accelerate the formation of a sc network between DPD4k and the PLLA matrix. The introduction of 10 wt % DPD4k also resulted in about 38 times longer relaxation time and a strain-hardening behavior during the steady biaxial extension of PLLA. At last, the continuous film blowing process was successfully conducted in the PLLA/DPD4k composites, which acquired a stable blow-up ratio of 3.07. On the basis of the above results, the soft chain-grafted PDLA copolymer may provide a novel method for film blowing of biodegradable PLA.
研究领域:
材料科学
·
高分子化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Chemistry B
·
2025
·
IF 5.7
Wenhao Yu,Dong Zhou,Fangrui Liu,Xu Li,Lan Xiao,Muhammad Rafique,Zhiyong Li,Joao Rodrigues,Ruilong Sheng,Yulin Li
Magnesium oxide (MgO) is known for its bioactivity and osteoconductivity when incprporated into biodegradable polylactide (PLA), while the weak interfacial bonding between MgO microspheres (mMPs) and PLA often leads to suboptimal composite properties with uncontrollable functionality. The conjugation of mMPs with PLA may offer a good way to enhance their compatibility. In this study, we systematically investigated two grafting techniques, solution grafting (Sol) and melt grafting (Mel) to decorate poly(D-lactic acid) (PDLA) on mMPs pre-treatmented by prioritized hydration to obtain Sol MPs and Mel MPs, in order to optimize the grafting efficiency and improve their controllability in the properties including crystal structure and surface morphology. Meanwhile, the Sol method shows an improved grafting ratio (2.9 times higher) compared to the Mel method. The conjugation of mMPs with PDLA effectively neutralized the rapid pH increase along degradation of pure mMPs, which could be used for sustainable delivery of Mg2+ ion release. Moreover, Sol MPs exhibited the lowest degradation rate constant, which could be well fitted by the first order dynamic model, suggesting a transformation of the mMPs degradation mode from bulk degradation to surface degradation. This change in biodegradation mode was beneficial for decreasing the over-basic effect caused by the quick degradation of pure mMPs, thus extending their application in development of PDLA/MgO composites towards tissue engineering or regenerative medicine.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POLYMER SCIENCE SERIES A
·
2017
·Vol. 59
·期 1
·116-123
·
IF 0.822
Shao Jun,Guo Yanmei,Ye Sitong,Xie Baomei,Xu Yaoyin,Hou Haoqing
The linear poly( L -lactide) and poly( D -lactide) (PLLA, PDLA) with relative lower molecular weights were synthesized, and PLLA/PDLA blends at various content of PDLA were prepared by solution casting. The morphology and growth of poly(lactide) stereocomplex (PLA SC) were investigated by polarized optical microscope. Results revealed that the morphology of SC in the blends strongly depended on the content of PDLA and the annealing temperature. Dendritic and irregular SC with looser structure developed in the specimens with lower content of PDLA, and regular SC spherulites with birefringent and compact structure produced in the specimens with higher content of PDLA. The growth rate ( G ) of SC increased gradually as the content of PDLA enhanced in the blends. As the annealing temperature enhanced, the SC with brighter and more compact structure appeared. The G value increased at first before declining as the annealing temperature elevated from the 130 to 190°C. And the nonlinear behavior of the growth of SC in the dissimilar specimens was analyzed.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2017
·Vol. 134
·期 17
·
IF 1.86
Yanmei Guo,Jun Shao,Haoqing Hou
Linear poly( d -lactide) (PDLA) with various molecular weights is synthesized and incorporated into commercial poly( l -lactide) (PLLA) with different optical purities. And then, the crystallization, mechanical and thermal properties of the PLLA and PLLA/PDLA cast films are investigated. In the PLLA and PDLA/PLLA specimens with lower optical purity, few homochiral crystallites (HC) form in all the specimens and only a small amount of PLA stereocomplex crystallites (SC) are observed in the blends. The elongation at break of all the specimens is extraordinary high, >300%. Dynamic mechanical analyses indicate that the destruction temperature increases at first, and then depresses as enlarging the molecular weight of PDLA in these blends. For the PLLA and PLLA/PDLA with higher optical purity, more content of HC develops in neat PLLA, and both SC and HC produce in the PLLA/PDLA specimens. However, the strains of neat specimens and binary blends are much lower than that of specimens with lower optical purity. The specimens with higher optical purity exhibit higher destruction temperatures and lower loss factors. The high content of crystals (SC and HC) would act as the physical cross-linking points and provide a key factor to impede the deformation of neat PLLA and binary blends during stretching, which should result in the fragile behavior of the PLLA and PLLA/PDLA blends with higher optical purity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44730.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Crystallization
·
2018
·Vol. 1
·期 1
·e10006
·
IF 0
Liying Wang,Congshu Feng,Dongdong Zhou,Jun Shao,Haoqing Hou,Gao Li
The phase transition behaviors of melt-quenched asymmetric poly( l -lactide acid)/poly( d -lactide acid) (PLLA/PDLA) blends are investigated by the in-situ wide angle X-ray diffraction. Results indicate that the crystal structures and their transition of PLLA/PDLA specimens depend on the composition, molecular weight, and temperature. In the specimens with lower molecular weights (∼9 kg/mol), the poly(lactic acid) homocrystallites (HC), mesophase, and stereocomplex crystallites (SC) develop in specific blends. As the content of PDLA increases, the formation temperature of HC increases to a fixed value, while that temperature for SC reduces to a constant value, and the formation temperature of mesophase does not vary with composition. For the specimens with moderate molecular weights (∼30 kg/mol), the HC, modified HC, and SC develop in specific composition, the formation temperatures of both the HC are constant, and the formation of SC reduces to a fixed temperature. In the blends with molecular weight of ∼65 kg/mol, HC and SC develop, and the formation of HC does not vary, but that temperature for SC reduces slightly as more PDLA incorporated. After melting of HC, another enhancement of SC is observed in all the PLLA/PDLA specimens. The unique crystallization phenomena for these PLLA/PDLA specimens are analyzed.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
CHINESE JOURNAL OF POLYMER SCIENCE
·
2015
·Vol. 33
·期 12
·1713-1720
·
IF 1.835
Shao Jun,Liu Yan-long,Xiang Sheng,Bian Xin-chao,Sun Jing-ru,Li Gao,Chen Xue-si,Hou Hao-qing
In this study, the poly(L-lactide)/poly(D-lactide) (PLLA/PDLA) blends with different optical purities of PLLA and various molecular weights of PDLA are prepared by solution mixing, and the stereocomplex formation and phase separation behaviors of these blends are investigated. Results reveal that optical purity and molecular weight do not vary the crystal structure of PLA stereocomplex (sc) and homochiral crystallites (hc). As the optical purity increasing in the blends, the melting temperature of sc ( T
sc ) and the content of sc (Δ H
sc ) increased, while the melting temperature of hc ( T
hm ) hardly changes, although the content of hc (Δ H
hm ) decreased gradually. The T
sc and Δ H
sc are also enhanced as the molecular weight of PDLA reduces, and the Δ H
hm reduces rapidly even though the T
hm does not vary apparently. With lower optical purities of PLLA and higher molecular weights of PDLA, three types of crystals form in the blends, i.e. , PLA sc, PLLA hc and PDLA hc. As molecular weight decreases and optical purity enhances, the crystal phase decreases to two (sc and PDLA hc), and one (sc) finally. This investigation indicates that the phase separation behavior between PLLA and PDLA in the PLLA/PDLA blends not only depends on molecular weights, but also relies on the optical purities of polymers.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）