POLYMER DEGRADATION AND STABILITY
·
2019
·
IF 3.78
Piotr Rychter,Kamila Lewicka,Małgorzata Pastusiak,Marian Domański,Piotr Dobrzyński
Nowadays, researchers in the field of agrochemicals are trying to find effective methods to limit the excessive usage of pesticides and protect the environment. One of the most popular and promising techniques is the immobilization of pesticides using environment-friendly polymers. In the conducted research, it was demonstrated that the family of lactide/glycolide copolymers are unsuitable for this purpose due to very slow degradation in the soil. We examined influence of relatively small content of PEG blocks in newly synthesized poly( l -lactide-co-glycolide)-poly(ethylene glycol)–poly( l -lactide-co-glycolide) (PLGA–PEG–PLGA) on the degradation in soil, in activated sludge and usefulness of this terpolymers as a biodegraded carrier for the controlled release of two commonly used herbicides (Metazachlor and Pendimethalin). Presence of even small amount of PEG block in the terpolymer chain increases slightly the hydrophilicity of the polymeric chain, thereby increasing its susceptibility to hydrolytic and unexpectedly strongly to enzymatic degradation in soil environment. The amorphism of used as a carriers PLGA-PEG-PLGA terpolymers and the lack of the phenomenon of increasing the degree of crystallinity during degradation allow to achieve uniform progress of degradation, and thus is obtained a relatively constantly release of tested herbicides. In this way, it is possible to determine the optimal profile of degradation of polymer in soil and proper rate of diffusion and leaching of active agents which allows the release of herbicides in optimal and effective doses within 3–4 months of its application.
研究领域:
农业科学
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高分子化学
·
环境科学
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DOI
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 46
·24240-24247
·
IF 3.708
Qun Zhang,Xinde Tang,Tieshi Wang,Faqi Yu,Wenjuan Guo,Meishan Pei
Novel thermo-sensitive zwitterionic ABC-type triblock copolymers poly(ethylene glycol)-block-[2-(methacryloyloxy)ethyl]dimethyl(3-sulfopropyl)-ammonium hydroxide-block-poly[2-(dimethylamino)ethyl methacrylate] (MPEG-b-PSBMA-b-PDMAEMA) were synthesized by atom transfer radical polymerization (ATRP). The bromide-terminated diblock copolymers poly(ethylene oxide)-block-[2-(methacryloyloxy)ethyl]dimethyl(3-sulfopropyl)-ammonium hydroxide (MPEG-b-PSBMA-Br) were prepared by the ATRP of methacryloxyethyl sulfobetaine initiated by the macroinitiator MPEG-Br, which was obtained by the esterification of poly(ethylene glycol) monomethyl ether (MPEG) with 2-bromoisobutyryl bromide. Then, poly(2-(diethylamino)ethyl methacrylate) (PDMAEMA) was introduced by a sequential ATRP process to obtain the triblock copolymers. These copolymers with varied compositions, molecular weights and polydispersities were characterized by 1H NMR and GPC. Variable temperature ultraviolet analysis was employed to test their stimuli-sensitive properties. These block copolymers exhibited distinct thermo-sensitivity under different molecular compositions or solution conditions. The resistance to the non-specific protein adsorption of the triblock copolymers was evaluated, and excellent antifouling property occurred. This can be attributed to surface hydration via hydrogen bonds between PEG and water molecules and the surface hydration via ionic-induction between PSBMA and water molecules. The synergistic effect resulted in an effective reduction of protein adsorption. These copolymers have potential applications as antifouling and antibacterial agents.
研究领域:
材料科学
·
高分子化学
·
生物医学工程
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产品关联
DOI
高影响因子
PROGRESS IN ORGANIC COATINGS
·
2016
·
IF 2.632
Jiahui Su,Xiaoxuan Liu,Chengjing Xiong,Hong Huang,Yanyan Cui
In this study, we prepared a novel triblock copolymer, PDMS- b -(PMAEBB- co -PDMAEMA) 2 ( tri -PI) bearing side-chain benzophenone (BP) and coinitiator amine, as a macro-photoinitiator via reversible addition-fragmentation chain transfer (RAFT) copolymerization of the polymerizable photoinitiator 2-(methacryloyloxy)ethyl-2-benzoylbenzoate (MAEBB) and the unsaturated coinitiator amine 2-(dimethylamino)ethyl methacrylate (DMAEMA) with a bifunctional polydimethylsiloxane (PDMS) macro-chain transfer agent (macro-CTA). The structure of synthesized copolymer was confirmed by Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance ( 1 H NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The effects of the photoinitiator/coinitiator ratio, concentration, and photoinitiator systems on the photopolymerization kinetics of tri(propylene glycol) diacrylate (TPGDA) were investigated by real-time FT-IR. The mobility of the tri -PI chain segments was proven by X-ray photoelectron spectroscopy (XPS), and the surface morphology of TPGDA curing coatings was studied by scanning electron microscopy (SEM). Results showed that tri-PI strongly suppressed the effect of oxygen inhibition on the photopolymerization system. Tri-PI was also used in the curing of UV-curable waterborne polyurethane acrylate (UV-WPUA) resin to determine its versatility.
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
·
2017
·
IF 3.531
Le Li,Zhi-Qiang Cao,Rui-Ying Bao,Bang-Hu Xie,Ming-Bo Yang,Wei Yang
Different from traditional small molecular plasticizers, poly( l -lactic acid) (PLLA)-polyethylene glycol (PEG)-PLLA triblock copolymers were synthesized by ring-opening polymerization of L-lactide on the end hydroxyls of PEG and blended with PLLA, to enhance the crystallization of PLLA. Non-isothermal and isothermal crystallization studies show that the triblock copolymer enhances the crystallization of PLLA due to the nucleation effect from PLLA segments and the plasticization effect from PEG segments, which strongly depends on the structure of copolymers. With shorter PLLA segment and longer PEG segment of the triblock copolymer, the glass transition temperature and cold crystallization temperature of the blends decrease, and the degree of crystallinity and spherulite growth rate increase owing to the higher content of PEG. However, triblock copolymers with relatively longer PLLA segment and shorter PEG segment show unique nucleation effects for PLLA, leading to the elevation of crystallization temperature of PLLA. The results confirm that the crystallization acceleration of PLLA can be ascribed to the nucleation and plasticization effect, and the plasticization effect is more significant. What’s more, the introduction of triblock copolymers improves the compatibility and durability due to the good interfacial interaction with PLLA matrix even at a high loading.
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
Polymers
·
2022
·Vol. 14
·期 22
·4902
·
IF 4.967
Lei Hua,Xiaodong Wang
New biodegradable aliphatic PLLA-PBA-PLLA copolymers with soft poly(butylene adipate) (PBA) and hard poly(l-lactide) (PLLA) building blocks were synthesized via ring-opening polymerization (ROP). Proton nuclear magnetic resonance (1HNMR) was utilized to confirm the volume fraction of PBA (fPBA) within PLLA-PBA-PLLA. It was found that a PBA midblock (PBA-mid) within PLLA-PBA-PLLA-s (PLLA-PBA-PLLA triblock copolymer with a short PLLA block length) might display lamellar domain structure. However, PBA-mid within PLLA-PBA-PLLA-l (PLLA-PBA-PLLA triblock copolymer with a long PLLA block length) might locate itself as a nanoscale cylindrical domain surrounded by a PLLA continuous phase. Polymorphic crystals of PBA-mid within the PLLA-PBA-PLLA copolymers were formed after melt crystallization at the given temperatures, which were studied by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analysis. According to the WAXD and DSC analyses, it was interesting to find that the α-type crystal of PBA-mid was favorable to develop in the lower temperature region regardless of the state (crystallization or amorphous) of the PLLA component. Additionally, when the PLLA component was held in its amorphous state, it was easier for PBA-mid within the PLLA-PBA-PLLA copolymers to transform from the metastable β-form crystal to the stable α-form crystal. Furthermore, polarized optical microscopy (POM) photos provided direct evidence of the polymorphic crystals of PBA-mid within PLLA-PBA-PLLAs.Keywords:biodegradable aliphatic;triblock copolymers;polymorphic crystal
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
·
2021
·
IF 4.598
Tao Zhang,Wenshuo Zhang,Huihui Liu,Guannan Wang,Yuye Zhong,Mengwen Zhou,Qing Zhu,Houbin Li
The polymeric binders play a key role in the solid propellant, so the research on improving the performance of the binder has become particularly important. In this work, a novel fluorine-containing triblock copolymer PFPO-PTMG-PFPO and a fluorine-free triblock copolymer PECH-PTMG-PECH were obtained by the cationic ring-opening polymerization of 2-(2,2,3,3-Tetrafluoro-propoxymethyl)-oxirane (FPO) and epichlorohydrin (ECH) with Polytetramethylene Ether Glycol (PTMG), respectively. In comparison with PECH-PTMG-PECH, the three molecular weights of PFPO-PTMG-PFPO with fluorine-containing side chains had a higher glass transition temperature. With the increase of the fluorine-containing side chains, the molecular weights increased, and the T g also gradually increased from −64.1 ℃ to −51.8 ℃ in the DSC curves. The TGA-DTG curves indicated that three molecular weights of PFPO-PTMG-PFPO had a good thermal stability, and it was sharp weight loss temperature at around 368.0 ℃. Besides, the viscosity measurement indicated that the viscosity of the higher molecular weight of PFPO-PTMG-PFPO(c) (5357 g/mol) was lower than that of PFPO-PTMG-PFPO(b) (8266 g/mol). When a certain amount of fluorine-containing block was inserted, the influence of low friction coefficient of fluorine-containing polymer was dominant, in which performed the decreased polymer viscosity of the polymer as the increased molecular weight.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2015
·Vol. 54
·期 5
·678-685
·
IF 3.113
Chi Lv,Kun Cui,Shu-Cai Li,Hao-Tian Wu,Zhi Ma
New block copolymers Polystyrene- b -poly (2,2,2-trifluoroethyl acrylate)- b -Polystyrene (PS-PTFEA-PS) with controlled molecular weight ( M n =5000-11000 g⋅mol −1 ) and narrow molecular weight distribution ( M w / M n =1.13-1.17) were synthesized via RAFT polymerization. The molecular structure and component of PS-PTFEA-PS block copolymers were characterized through 1 H NMR, 19 F NMR, GPC, FT-IR and elemental analysis. The porous films of such copolymers with average pore size of 0.80-1.34 μm and good regularity were fabricated via a static breath-figure (BF) process. The effects of solvent, temperature, and polymer concentration on the surface morphology of such film were investigated. In addition, microstructured spheres and fibers of such block copolymers were fabricated by electrospinning process and observed by scanning electron microscopy (SEM). Furthermore, the hydrophobicity of porous films, spheres, and fibers was investigated. The porous film showed a good hydrophobicity with the water-droplet contact angles of 129°, and the fibers showed higher hydrophobicity with the water-droplet contact angles of 142°. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54 , 678–685
研究领域:
高分子化学
·
材料科学
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
·
2018
·Vol. 56
·期 11
·865-876
·
IF 2.499
Zuxiang Xu,Jinhui Li,Guorong Gao,Zongbao Wang,Yang Cong,Jing Chen,Jingbo Yin,Lei Nie,Jun Fu
Tough hydrogels have great potentials in soft robotics, artificial muscles, tissue replacement, and so on. Here we introduce novel tough hydrogels crosslinked by triblock copolymer (F127DA) micelles and metal coordination. The gels showed outstanding tensile strength (∼1–11 MPa), toughness (∼4–32 MJ m −3 ), and excellent self-recovery properties (∼56.8–87.2% toughness recovery in 9 min at room temperature). The mechanical and self-recovery properties could be manipulated by varying contents of micelles and/or COO − groups. Dynamic mechanical analysis of the hydrogels revealed apparent activation energy and relaxations for both physical interactions. In situ small-angle X-ray scattering measurements on hydrogels upon stretching revealed micelle deformations. XPS measurements on hydrogels before and after stretching revealed significant changes in the binding energy of Fe 3+ ions in the gels, suggesting the rupture of coordination bonds. The experimental results strongly suggest a synergistic effect from the micelle-crosslinking and Fe 3+ –COO − coordination on the strength, toughness, and self-recovery of the hydrogels. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56 , 865–876
研究领域:
材料科学
·
高分子化学
·
生物医学工程
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2013
·Vol. 38
·期 2
·490-494
·
IF 2.966
Tieshi Wang,Xinde Tang,Qun Zhang,Faqi Yu,Wenjuan Guo,Guangyou Zhang,Meishan Pei
Well-defined amphiphilic triblock copolymers PMAGP-b-PLA-b-PMAGP with varied compositions and molecular weights were obtained via a four-step procedure. The hydrophilicity and water absorption increase with an increase of the PMAGP chain length. The presence of active hydroxyl groups was confirmed by a dyeing procedure.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
Scientific Reports
·
2020
·Vol. 10
·期 1
·1-12
·
IF 3.998
Wu Yifan,Li Lingtong,Chen Shaopeng,Qin Jun,Chen Xiaolang,Zhou Dengfeng,Wu Hong
Poly( D -lactic acid) (PDLA) with different polyethylene glycol (PEG) segment synthesized PDLA-PEG-PDLA triblock copolymer through the ring-opening reaction of D -LA and PEG will be used as a toughening modifier. The microstructure, crystal structures and crystallization behaviors of this triblock copolymer were investigated by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The triblock copolymer is synthesized from the appearance of CH 2 stretching vibration peak at 2910 cm −1 and C-O stretching vibration peak at 1200 cm −1 from PEG in FTIR spectra. Moreover, the chemical shift that is about 3.6 ppm in 1 H NMR and 68.8ppm in 13 C NMR proves this matter. The results of XRD and DSC reveal that PDLA and PEG are crystallized separately, and are not fully compatible, and microphase separation has occurred in this triblock copolymer. PEG can induce the triblock copolymer to accelerate the rate of crystallization, allowing it to crystallize more completely in the same amount of time. When the molecular weight of PEG is 6000 or the ratio of D -LA/PEG is 1/1, the crystallizability of PDLA-PEG-PDLA triblock copolymer is the best.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 34
·14551-14559
·
IF 3.288
Cheng Zhou,Yan Chen,Mingjun Huang,Yi Ling,Liming Yang,Guochen Zhao,Jie Chen
A brand new pH and thermo-responsive amphiphilic ABC triblock copolymer of poly(acrylic acid)-block-poly(N,N-dimethyl acrylamide)-block-poly(acrylamide-co-acrylonitrile) (PAA-b-PDMA-b-P(AM-co-AN)) was synthesized via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization. Due to the pH-responsive blocks of PAA and thermo-responsive blocks of P(AM-co-AN), the properties of the copolymer solution were controlled by varying parameters such as temperature and pH. Specifically, it formed different nanostructures and showed gel behavior under different conditions. In detail, under high temperature alkaline conditions, ADAA was dissolved in an aqueous solution in the form of a molecular chain. Thereafter, when the temperature became lower or pH became acidic, the triblock copolymer self-assembled into different micelle structures, including shell–core, core–shell–core and tighter core–linking–core nanoparticles. In addition, the phase transition temperature of the copolymer was adjusted by pH and concentration. When the copolymer hydrogel was injected into a simulated human body device, it showed sustained drug release behavior and low transient drug concentrations. MTT experiments demonstrated the good biocompatibility of the ADAA hydrogels. This research provides inspiration to develop new polymers which are expected to be promising candidates as part of drug delivery platforms. Compared with traditional responsive hydrogels, its UCST can be easily controlled and is more stable through the feeding ratio, making it more advantageous in human drug delivery applications. In summary, we believe that this UCST and pH-responsive injectable ADAA hydrogel is researchable and applicable in the biomedical field.
研究领域:
材料科学
·
生物医学工程
·
药学
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DOI
高影响因子
POLYMER BULLETIN
·
2020
·Vol. 78
·期 2
·753-768
·
IF 2.014
Wu Jie,Zhai Wentao,Gao Xue,Liu Bingxin,Zhang Ruling,Yu Yueqin
Well-defined triblock copolymers poly( N -isopropylacrylamide)-b-poly(3-methacryloxypropyltrimethoxysilane)-b-poly( N -isopropylacrylamide) (PNIPAM-b-PMEMO-b-PNIPAM) with varying block ratios were successfully synthesized via reversible addition–fragmentation chain transfer polymerization. The amphiphilic triblock copolymers showed surfactant-like behavior in aqueous solution and could easily self-assemble into dendritic micelles with hydrophobic PMEMO as the core and hydrophilic PNIPAM as the shell when the copolymer concentration exceeded the critical micelle concentration (CMC). Transmittance measurements showed the triblock copolymers were thermosensitive, and it was worth noting that the lower critical solution temperature (LCST) values of copolymers exceeded pure PNIPAM to about 35.3 °C, which was very close to physiological temperature of human body. This was attributed to the effect of Si–O–CH 3 hydrolysis in polymers. The effect of a series of inorganic salts on thermosensitivity of PNIPAM-b-PMEMO-b-PNIPAM was investigated, and our results suggested that the block copolymers maintained good thermosensitivity in all salt solutions. The LCST did not change significantly in different concentrations of NaCl, CaCl 2 and MgCl 2 solutions, which proved the polymer had good salt resistance. Dynamic light scattering experiments showed that the micelles were well dispersed at about 120 nm below LCST with a small polydispersity index. In addition, the drug-loading experiments of micelles showed high drug encapsulation efficiency indicating their potential as drug carriers.
研究领域:
材料科学
·
生物医学工程
✓ 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）