MACROMOLECULAR CHEMISTRY AND PHYSICS
·
2011
·Vol. 212
·期 23
·2589-2593
·
IF 2.437
Hongjun Yang,Manqing Yan,Stergios Pispas,Guangzhao Zhang
Poly[(ethylene carbonate)- co -(ethylene oxide)] is synthesized by ROP of 1,3-dioxolan-2-one using 1- tert -butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylidenamino]-2Λ5,Λ5-catenadiphosphazene as the catalyst. NMR spectroscopy shows that the copolymer chain consists of EO-EC-EO-EO sequences. GPC measurements indicate a PDI of 1.43–1.66 and show that the molecular weight increases with monomer conversion. Thermal analysis demonstrates that the copolymer is amorphous with a glass transition temperature of about –42 °C and an onset decomposition temperature of about 200 °C.
研究领域:
材料科学
·
聚合物化学
✓ 已验证
DOI
高影响因子
POLYMER
·
2015
·
IF 3.562
Huanhuan Liu,Xiao Jiang,Rongjian Bian,Min Tong,Dandan Tang,Xiangdong Zhou,Youliang Zhao
Controlled synthesis of A 2m B 2n -type (m ≈ n ≈ 8) starlike copolymers comprising an oligomeric poly(styrene- co -maleimide) core and two types of V-shaped arms individually generated by ATRP and ROP was described. Multistep syntheses involving RAFT copolymerization , end group removal, ATRP of vinyl monomers such as styrene (St), methoxyethyl methacrylate (MEMA) and tert -butyl acrylate ( t BA), and ROP of ε -caprolactone (CL) were used to construct the target miktoarm stars with controlled molecular weight and relatively low polydispersity (PDI = 1.07–1.22). The resultant star copolymers had high bromide functionality and uniform chain length of ATRP-generated arms, evident from chain extension polymerization and cleavage of arms. Meanwhile, a pH-responsive (PAA) 2m (PCL) 2n star was also obtained by selective hydrolysis. The synthetic strategy via combination of RAFT copolymerization and “core first” approach is versatile in constructing various A 2m B 2n stars, and this study further paves way for facile synthesis and properties of new types of miktoarm stars.
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
JOURNAL OF ORGANOMETALLIC CHEMISTRY
·
2016
·
IF 2.336
Xiang-Xin Zheng,Zhong-Xia Wang
Di(aminomethylpyrrolyl)methane derivatives [2-{5-R′ 2 NCH 2 (C 4 H 2 NH)}] 2 CR 2 ( 2a R = Et, R′ = Me; 2b R = Ph, R′ = Me; 2c R = Ph, R′ = Et; 2d R 2 = 1,1′-biphenyl-2,2′-diyl, R′ = Me; 2e R 2 = 1,1′-biphenyl-2,2′-diyl, R′ 2 = (CH 2 ) 4 ) were prepared through reaction of di(1 H -pyrrol-2-yl)methane derivatives (2-C 4 H 3 NH) 2 CR 2 ( 1a R = Et; 1b R = Ph; 1c R 2 = 1,1′-biphenyl-2,2′-diyl) with formaldehyde and amines. Treatment of 2a with 3 equiv. of ZnEt 2 in toluene afforded trinuclear zinc conplex 3a , while respective reaction of 2b - 2e with 3 equiv. of ZnEt 2 in toluene or THF produced dinuclear zinc complexes 3b - 3e . Each of the complexes was characterized by 1 H and 13 C NMR spectroscopy and elemental analysis . Structures of complexes 3a and 3b were additionally characterized by single crystal X-ray diffraction. Catalysis of complexes 3a - 3e toward the ROP of rac -lactides was evaluated in both toluene and THF. Each complex was active in the catalysis in the presence of benzyl alcohol (BnOH). 3a showed the highest activity in toluene and 3c was the most active in THF. Kinetic study of complexes 3a and 3e was carried out and the results showed that the polymerization catalyzed by 3e /BnOH follows a first-order kinetics, while 3a /BnOH-catalyzed polymerization followed neither first-order nor second-order kinetics.
研究领域:
有机化学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2019
·
IF 5.997
Na Zhao,Chuanli Ren,Yong Shen,Shaofeng Liu,Zhibo Li
Degradable long-chain aliphatic polyesters are promising alternatives to polyolefins. The ring-opening polymerization (ROP) of ω-pentadecalactone (PDL) enables the synthesis of aliphatic polyesters with melting temperature close to low-density polyethylene (LDPE). However, this ROP reaction is of great challenge because of low ring strain of the PDL monomer. The occurrence of intra- and intermolecular transesterification reactions during ROP made it difficult to prepare well-defined block copolyesters for advanced properties. In this context, cyclic trimeric phosphazene base (CTPB) in combination with benzyl alcohol (BnOH) was proved to be an efficient initiator system for ROP of PDL, showing an excellent polymerization rate (TOF up to 600 h–1) at 80 °C. Well-defined diblock copolyesters, i.e., PPDL-b-PLLA, can be easily synthesized by sequential addition of PDL and l-lactide (L-LA). In contrast, sequential addition of PDL and ε-caprolactone (CL) or δ-valerolactone (VL) only led to the random copolyesters under the same conditions. On the other hand, CTPB is an inherent tribasic superbase and can be partially neutralized to decrease its basicity for better control over active lactones such as CL and VL. Hence, we introduced 0.33–1.0 equiv of benzoic acid (PhCOOH) relative to CTPB and demonstrated that it can diminish the transesterification during ROP of CL or VL. Based on this strategy, PPDL-b-PCL or PPDL-b-PVL diblock copolyesters were successfully prepared by sequential addition of monomers of CL or VL after ROP of PDL. The block copolyester structures were confirmed by the 13C NMR spectroscopy and DSC characterizations.
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
OPTICAL MATERIALS
·
2020
·
IF 2.779
Chen Liang,Jianhua Hou,Yanhui Li,Dajun Liu,Jian Li,Xu Cui,Qian Duan
Well-controlled brush-shaped block copolymers (BBCPs) of high molecular weight with polystyrene (PS) and polylactic (PLA) side chains, (poly (cis-5-norbornene-exo-2,3-dicarboximide-end poly (styrene)))-block-(poly (cis-5-norbornene-exo-2,3-dicarboximide-end poly (lactide))) (PNB- g -PS)- b -(PNB- g -PLA) were synthesized by combining atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). The synthesis of the (PNB- g -PS)- b -(PNB- g -PLA) was well-controlled with molecular weight and polydispersity index ( M n, GPC = 1310000 g mol - 1 and M w / M n (GPC) = 1.16). The SEM, XRD and DSC reveal that there are two immiscible cis-5-norbornene-exo-2,3-dicarboximide-end poly(styrene) (NB-PS) and cis-5-norbornene-exo-2,3-dicarboximide-end poly(lactide) (NB-PLA) phases in BBCP after self-assembly, which leads to partial crystallization. Moreover, the effect of the self-assembly temperature on morphology and reflectance of (PNB- g -PS)- b -(PNB- g -PLA) has been investigated. These (PNB-g-PS)-b-(PNB-g-PLA) exhibit obvious pearlescent appearance and wide band reflection after heat-treated at different temperatures (120 °C, 130 °C, 140 °C and 150 °C). Besides, with the increase of the self-assembly temperature, the domain spacing of (PNB- g -PS)- b -(PNB- g -PLA) decreases and the reflectance in visible range of (PNB- g -PS)- b -(PNB- g -PLA) increases. However, the self-assembly temperature does not significantly influence the reflection wavelength range of (PNB- g -PS)- b -(PNB- g -PLA).
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2012
·
IF 3.628
Yanzhu Guo,Xiaohui Wang,Zuguang Shen,Xuancai Shu,Runcang Sun
Self-associating cellulose- graft -poly( ɛ -caprolactone) (cellulose- g -PCL) copolymers were successfully synthesized via homogeneous ring-opening polymerization (ROP) of ɛ -CL onto softwood dissolved pulp substrate in ionic liquid 1-N-butyl-3-methylimidazolium chloride ([Bmim]Cl). An organic catalyst N,N-dimethylamino-4-pyridine (DMAP) was compared with the traditional metal-based catalyst (Sn(Oct) 2 ) as the catalyst of the reaction, and exhibited higher catalytic activity. By controlling the cellulose: ɛ -CL feed ratio and reaction temperature, the molecular architecture of the copolymers can be altered, as evidenced by FT-IR, 1 H NMR, 13 C NMR, TGA and XRD. The self-assembly behavior of the copolymers in water was investigated and characterized using fluorescence probe, dynamic light scattering (DLS) and SEM. The results showed that the cellulose- g -PCL copolymers could form nanosized micelles (approximately 20–100 nm) in water, and the micelle size and critical micelle concentration (CMC) can be controlled by varying the grafting ratio of PCL. These cellulose-based nanomicelles are expected to be useful in broad application fields.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Journal of Renewable Materials
·
2015
·Vol. 3
·期 2
·113-119
·
IF 0
Liu Yadong,Huang Guangcheng,Pang Yuanyuan,Han Miaomiao,Ji Shengxiang
In this work, we report a one-pot synthesis of amphiphilic miktoarm cellulose graft copolymers, cellulose (-graft-oligo(L-lactide))-graft-oligo(N-isopropylacrylamide) (Cell(-g-OLLA)-g-ONIPAM), with dual side chains of oligo(L-lactide) and oligo(N-isopropylacrylamide)
using 2-bromoisobutyl bromide functionalized cellulose (Cell(-OH)-Br) as the macroinitiator, by simultaneously conducting ring-opening polymerization and atom transfer radical polymerization using Cu/CuBr/PMDETA/Sn(Oct)2 as the catalytic system. The chemical structures and thermal
properties of Cell(-g-OLLA)-g-ONIPAMs were characterized with 1H and 13C nuclear magnetic resonance spectroscopy, differential scanning calorimetry and thermal gravimetric analysis. Cell (-g-OLLA)-g-ONIPAM could self-assemble into micelles
in the aqueous solution as confirmed by environmental scanning electron microscopy and dynamic light scattering analyses. The micellar aggregates showed a temperature-responsive property and the sizes of micelles were influenced by the ratio of temperature-responsive ONIPAM side chains. The
miktoarm graft copolymers have potential applications as biomedical or intelligent materials.
研究领域:
高分子化学
·
材料科学
·
生物医学工程
·
响应性材料
·
纳米技术
✓ 已验证
DOI
EUROPEAN POLYMER JOURNAL
·
2014
·
IF 3.242
Ting-Ting Xu,Jun Zhu,Cong Yuan,Qian-Li Yang,Kun Cui,Chun-Hui Li,Liu-He Wei,Zhi Ma
A series of new polymethylene- b -poly(styrene- co -2-hydroxyethyl methacrylate) (PM- b -P(St- co -HEMA)) and polymethylene- b -poly(styrene- co -2-hydroxyethyl methacrylate- g -poly(ε-caprolactone)) (PM- b -P(St- co -HEMA- g -PCL)) copolymers were successfully synthesized via a strategy combined polyhomologation of ylides, reversible addition–fragmentation chain transfer (RAFT) polymerization and ring-opening polymerization (ROP). Firstly, a hydroxyl terminated polymethylene (PM-OH) was obtained via polyhomologation of ylides followed by oxidation. Then, PM-OH was transformed to a macromolecular chain transfer agent (PM-CTA). Subsequently, RAFT copolymerizations of styrene (St) and 2-hydroxyethyl methacrylate (HEMA) were performed using PM-CTA as chain transfer agent, targeting the well-defined PM- b -P(St- co -HEMA) copolymers with controllable molecular weight and narrow molecular weight distribution. Finally, the ring-opening polymerization of ε-caprolactone was carried out using PM- b -P(St- co -HEMA) copolymer as initiator to achieve PM- b -P(St- co -HEMA- g -PCL) copolymer. The molecular weight and chain structure of the obtained copolymers were characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance ( 1 H NMR) and Fourier Transform Infrared spectroscopy (FTIR). Moreover, the fabrication of highly ordered porous films using the amphiphilic PM- b -P(St- co -HEMA) copolymers via a static breath-figure process was investigated.
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
EUROPEAN POLYMER JOURNAL
·
2023
·
IF 6
Shuaijie Chen,Minghui Yang,Haihui Li,Haitao Zhao,Xiang Xu,Weiwei He,Lifen Zhang,Zhenping Cheng
Photoinduced reversible-deactivation radical polymerization (RDRP) has attracted great interest in virtue to their unique inherent advantages, such as low activation energy, environmentally benign reaction conditions and precision synthesis of designable functional polymeric materials. In this work, a facile and efficient strategy for preparing block copolymers was developed by the combination of near-infrared (NIR) light-controlled in-situ bromine-iodine transformation reversible-deactivation radical polymerization (BIT-RDRP) and purple LED light induced ring-opening polymerization (ROP). Herein, the macroinitiator was first synthesized via NIR light-controlled BIT-RDRP by using a bifunctional 2-hydroxyethyl 2-bromo-2-phenylacetate (EBP-OH) as the initiator at room temperature. Subsequently the block copolymers with narrow dispersity (low up to 1.06) were prepared by combination of purple LED light induced ROP through “two step” or “one pot” process. Importantly, the “one pot” strategy can greatly simplify the operation process and improve the synthesis efficiency, which will facilitate the batch preparation of block copolymers.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
POLYMER
·
2020
·
IF 4.231
Yuanyuan Zhang,Wenjie Ren,Qiuxiang Zhao,Kuiying Lv,Yangjian Sun,Xin Gao,Fanye Wang,Junhong Liu
A one-pot ring-opening polymerization (ROP) to form poly ε-caprolactone (PCL) from cyclohexanone (CHN) mediated by immobilized T. laibacchii lipase was proposed. The optimal conditions by using response surface methodology (RSM) were established as follows: the supplement of lipase , 23.55 mg, the reaction temperature, 59.4 °C and the molar ratio of urea hydrogen peroxide (UHP) to CHN, 1.31:1, under which the yield of PCL and number-average molar mass (Mn) at a high CHN concentration of 1.25 M were 96.5% and 2912, respectively. The one-pot ROP consists three steps: first, ethyl acetate (EtOAc) reacts with UHP to generate peracetic acid catalyzed by lipase; then, CHN is lactonized to ε-caprolactone (CL) with peracetic acid in situ generated in nonenzymatic, and acetic acid formed reacts with UHP to form peracetic acid; finally, CL suffers from enzymatic ROP to in situ generate PCL. There are three factors contributing to the high yield: cross-linked immobilized lipase employed, the supplement of lipase added in step 3 of ROP and optimal conditions adopted. The initial concentration of UHP was reduced from 2.5 M to 1.625 M owing to acetic acid reacting with UHP to yield peracetic acid which can help obtain a high yield of PCL. A kinetic model for this one-pot three-step enzymatic ROP reaction was developed, which fitted the observed data well. The enzymatic reaction mediated by lipase may obey the ping-pong mechanism with substrate inhibition of UHP and acetic acid, while the nonenzymatic reaction may obey a power law. Using the kinetic model , the contribution of the reaction of UHP with EtOAc and acetic acid to the yield of peracetic acid can be distinguished, contributing to better comprehend the reaction process.
研究领域:
生物化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 22
·6687-6703
·
IF 6.177
Furong Cao,Yun Wang,Xing Wang,Wenjuan Zhang,Gregory A. Solan,Rui Wang,Yanping Ma,Xiang Hao,Wen-Hua Sun
Five types of N-(2-(diphenylphosphino)ethyl)-2-R-5,6,7,8-tetrahydroquinolin-8-amines (R = H L1, Me L2, iPr L3, Cl L4, Ph L5) along with one example of an N-isopropyl-5,6,7,8-tetrahydroquinolin-8-amine (L6) have been prepared and employed as neutral ligand supports for zinc(II) chloride complexes, LZnCl2 (Zn1–Zn6). All zinc compounds were characterized by multinuclear NMR spectroscopy (1H/13C/31P) and elemental analysis, while the structures of Zn2 and Zn5 were further studied by single crystal X-ray diffraction: distorted tetrahedral geometries with the diphenylphosphine moieties non-coordinated were a feature. Pre-treatment of Zn1–Zn5 with two equivalents of either LiCH2SiMe3 or LiN(SiMe3)2 led to catalysts displaying good to exceptionally high activity for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) at 50 °C. For example, Zn4/2LiCH2SiMe3 displayed a TOF of 2.1 × 104 h−1 with 71% conversion seen within 10 minutes with the ε-CL : Zn molar ratio at 5000 : 1; the resulting polycaprolactone (PCL) comprised predominately cyclic structures along with lower levels of trimethylsilylmethyl-capped linear PCL. By comparison, Zn1–Zn5 on treatment with two equivalents of LiN(SiMe3)2 at the same high monomer to zinc ratio, led to catalysts exhibiting an order of magnitude higher activity. Zn1/2LiN(SiMe3)2 in the presence of BnOH exhibited a remarkable TOF of 1.35 × 105 h−1 with 90% monomer conversion within two minutes. In these cases, a distinct selectivity towards linear polymers capped with CH3O end-groups (derived from the quenching solvent) was observed with cyclic polyesters only observable with larger amounts of ε-CL. As a general observation, the 2-R substituent on the chelating ligand showed noticeable effects on the efficiency and on the molecular weight of the PCLs, with 2-Cl-containing Zn4 in combination with LiCH2SiMe3 and BnOH affording the highest molecular weight PCL of the study (9.57 × 104 g mol−1). Based on the microstructural properties of the PCL, distinct mechanisms (viz., coordination–insertion and ring expansion) have been proposed to account for the mode of propagation mediated by Zn/2LiCH2SiMe3 and Zn/2LiN(SiMe3)2. In addition, a zinc silylamido L1−HZn[N(SiMe3)2] (Zn7) species has been tentatively assigned (obtained via deprotonation of L1 with Zn[N(SiMe3)2]2), that proved inactive for the ROP of ε-CL but displayed good activity for ROP of rac-LA.
研究领域:
有机化学
·
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Ya-li Xiang,Ling-ling Yan,Luo-lin Deng,De-yu Tang,Xin-yang Liu,Juan Lin,Qing-han Zhou
Novel strategy is urgently needed to overcome the bacterial infection all over the world due to unreasonable use of biotics. In recent years, nanozymes have attracted great interests of researchers for their high catalytic efficiency and biocompatibility. In this study, a novel multiple enzyme-mimic polypeptide-based carbon nanoparticle was synthesized by N-carboxyanhydride mediated ring opening polymerization (ROP) and Fe coordination for actualizing ROS regulation and photo-thermal therapy. The multiple enzyme-mimic activities of the nanozyme, such as peroxidase, oxidase, catalase, and glutathione peroxidase, were detailly explored in ROS regulation for potential utilization in bacterial inhibition. The photo-thermal effect of the nanozyme was investigated under 808 nm NIR irradiation. Enhanced inhibition rate of the as prepared nanozyme was observed against Gram-negative Escherichia coli (99.03 %) and Gram positive Staphylococcus aureus (99.78 %) planktonic bacteria. Methicillin-resistant Staphylococcus aureus ( MRSA ) was chosen as the drug resistant bacteria model to evaluate the efficiency in bacterial biofilm disruption. Improved healing efficacy of 99.05 % against MRSA wound infection and excellent biosafety were observed in mice model experiments for the as prepared nanozyme. In conclusion, the as synthesized nanozyme with ROS regulation, enhanced bacteria inhibition, and excellent biocompatibility could be potentially applied in clinic against bacterial infection.
研究领域:
纳米技术
·
生物医学工程
·
材料科学
·
微生物学
·
治疗学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）