Rapid synthesis of biodegradable poly(epsilon-caprolactone-co-p-dioxanone) random copolymers under microwave irradiation

Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In th...

Engineering Antibacterial Activities and Biocompatibility of Hyperbranched Lysine-based Random Copolymers

Antimicrobial peptides(AMPs)have been considered as an alternative to small molecule antibiotics since they are difficult to develop antimicrobial resistance.Hyperbranched polylysine(HPL),an AMP mimics,has gained attention due to its broad-spectrum antibacterial activities,but it also suffers from high toxicity.Here we report a facile strategy to engineer the toxicity of HPL by copolymerizing lysine(K)with a hydrophobic amino acid,e.g.,alanine(A),tryptophan(W)or phenylalanine(F),to afford hyperbranched random copolymers.These copolymers have comparable antibacterial activities to HPL while their cytotoxicities and in vivo toxicities are lowered when the type and content of hydrophobic amino acid and the size of copolymers are optimized.The G.mellonella infection model demonstrates that the copolymers are effective against the S.aureus infection in vivo.The copolymers kill the bacteria through the disruption of cell membranes and the bacteria do not develop resistance to the copolymers.

Micelle-crosslinked hydrogels with stretchable,self-healing,and selectively adhesive properties:Random copolymers work as dynamic yet self-sorting domains

The design of crosslinking domains is a vital factor to create functional hydrogels with controlled physical,mechanical,and adhesive properties.This paper demonstrates versatile synthetic systems of micelle-crosslinked hydrogels with highly stretchable,self-healing,and selectively adhesive properties.For this,methacrylate-bearing random copolymer micelles are designed as physical and covalent crosslink domains via the self-assembly of amphiphilic random copolymers carrying hydrophilic poly(ethylene glycol)(PEG),hydrophobic butyl or dodecyl groups,and methacrylate-terminal PEG in water.The size,aggregation number,and pendant methacrylate number of the micelles are controlled by the composition and degree of polymerization.Hydrogels are efficiently obtained from the free radical polymerization of hydrophilic monomers such as PEG acrylate and acrylamide in the presence of the micelle crosslinkers in water.Owing to the dynamic yet selective chain exchange properties of the micelle domains,the hydrogels are highly stretchable up to over 1000%and show self-healing and selectively adhesive properties.The self-healing of hydrogels is promoted upon heating due to the fast chain exchange of the micelle domains,whereas hydrogels consisting of micelles with different alkyl groups are never adhesive because of their self-sorting properties.

Copolymerization of PO/CO_(2)and Lactide by a Dinuclear Salen-Cr(Ⅲ)Complex:Gradient and Random Copolymers with Modificable Microstructure

Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we designed a dinuclear Salen-Cr(Ⅲ)complex,which showed higher efficiency for copolymerization of PO/CO_(2)and LA than that of mononuclear Salen-Cr(Ⅲ)complex.Besides,we successfully obtained gradient and random copolymers of PPC-PLA in one pot.Furthermore,by adjusting reaction temperature,block ratios of PPC/PLA in copolymers were controllable(block ratio of PPC/PLA=1.0 at 40℃,while block ratio of PPC/PLA=0.5 at room temperature).While increasing the reaction temperature to 60℃,conversion of LA was much faster than that of PO so that gradient copolymers were obtained.

Random Copolymers Based on Thieno[3,4-c]pyrrole-4,6-dione and Isoindigo Building Blocks for Polymer Solar Cells

Three random conjugated polymers,RP-TiI,RP-2TiI and RP-TVTiI based on both thieno[3,4-c]pyrrole-4,6-dione and isoindigo units have been synthesized by Stille cross-coupling reaction.The optical and electrochemical properties of new polymers have been investigated.The resulted polymers showed broad absorption spectra and appropriate energy levels for polymer solar cell applications.The bulk heterojunction devices based on the blend of the polymer RP-TiI and PC_(61)BM showed a power conversion efficiency of 1.75%.

Influence ofβ-nucleating Compound Agents on the Mechanical Properties and Crystallization Behavior of Polypropylene Random Copolymer

A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifier(TPE/WBG-2/CaCO_(3)).The effects of differentβ-nucleating agents and ternary compound modifier on the mechanical properties and crystallization behavior of PPR were analyzed.The results show that,compared with pure PPR materials,both WBG-2 and TMB-5 could significantly improve the impact strength of PPR.The crystallization temperature of PPR increased with the addition ofβ-nucleating agent.The modified PPR prepared with ternary compound modifier showed the most excellent comprehensive properties.

TIME AND POLING HISTORY DEPENDENT ENERGY STORAGE AND DISCHARGE BEHAVIORS IN POLY(VINYLIDENE FLUORIDE-CO-HEXAFLUOROPROPYLENE) RANDOM COPOLYMERS

We studied cycle time （0.01-10 s with triangular input waves） and poling history （continuous versus fresh poling） dependent electric energy storage and discharge behaviors in poly（vinylidene fluoride-co-hexafluoropropylene） [P（VDF- HFP）] films using the electric displacement -- the electric field （D-E） hysteresis loop measurements. Since the permanent dipoles in PVDF are orientational in nature, it is generally considered that both charging and discharging processes should be time and poling history dependent. Intriguingly, our experimental results showed that the charging process depended heavily on the cycle time and the prior poling history, and thus the D-E hysteresis loops had different shapes accordingly. However, the discharged energy density did not change no matter how the D-E loop shape varied due to different measurements. This experimental result could be explained in terms of reversible and irreversible polarizations. The reversible polarization could be charged and discharged fairly quickly （〈 5 ms for each process）, while the irreversible polarization depended heavily on the poling time and the prior poling history. This study suggests that it is only meaningful to compare the discharged energy density for PVDF and its copolymer films when different cycle times and poling histories are used.

Synthesis and Characterization of Poly(L-lactide-co-ε-caprolactone) Copolymers

A series of random and block poly（ L-lactide-co-e-caprolactone ） （ PCLA ） copolymers whh different composition are prepared using stannous octaoate as catalyst.The effects of the amount of initiator on the intrinsic viscosity have been investigated. The structure of the PCLA copolymers is characterized by means of nuclear magnetic resonance（ NMR ）, Fourier transform infrared spectrum （ FTIR ）, differential scanning calorimetry （ DSC ） and X- ray diffraction （ XRD ） methods. It is shown that the synthesis condition and the composition of copolymers obrious influence on the structure of PCLA copolymers. Hydrolytic degradation of the copolymers in a PBS solution of pH 7.4 at 37.0℃ shows that the copolymers of different composhions degrade at different rates.

SYNTHESIS AND CHARACTERIZATION OF RANDOM OR GRADIENT BUTADIENE-p-METHYLSTYRENE COPOLYMERS VIA ANIONIC POLYMERIZATION

Copolymers of 1,3-butadiene and p-methylstyrene （p-MS） were synthesized via anionic polymerization. A benzophenone-potassium complex was added to tune the reactivity ratio of the two monomers, leading to random and gradient composition alonglthe copolymer chain. The overall composition and microstructure could be controlled and well characterized by GPC and H-NMR. The p-MS was distributed from gradient to random with increasing the content of the benzophenone-potassium complex, and the 1,2-microstrucmre in the polybutadiene sequence increased at the same time. The hydrogenation of the copolymer of 1,3-butadiene and p-MS resulted in the corresponding saturated copolymer with well- defined structure and narrow molecular weight distribution.

Anionic synthesis of binary random in-chain multi-functionalized poly(styrene/butadiene/isoprene and dimethyl [4-phenylvinyl)-phenyl]silane)(PS-DPESiH,PB-DPESiH,PI-DPESiH) copolymers

The binary random in-chain silyl-hydride multi-functionalized poly（styrene/butadiene/isoprene and dimethyl[4-（1-phenylvinyl） phenyl]silane） （PS-DPESiH, PB-DPESiH, PI-DPESiH） copolymers were successfully synthesized. These functionalized copo- lymers were prepared in hexane with n-BuLi as the initiator at 50℃ for 4 h. The silyl-hydride groups were introduced into polymer backbones quantitatively by living anionic polymerization. The copolymers were determined through 1H NMR, size exclusion chromatography （SEC） and differential scanning calorimetry （DSC） techniques, while the number of silyl-hych-ide groups was calculated and discussed.

Amphiphilic random polycarbonate self-assemble into GSH/pH dual responsive micelle-like aggregates in water

Responsive polymers have been playing an increasingly important role in a wide variety of applications,such as biomedical materials and biosensors.Herein,we reported a dual-responsive polycarbonate(poly(MN-co-MSS)) based on the macrocyclic Sulfur/Nitrogen-substituted carbonate monomer(MSS/MN) via an enzyme-catalyzed ring-opening copolymerization and Lipase CA Novozym-435 as catalyst,with the disulfide and tertiary amine groups situated on the backbone.The structure of the random copolymers was confirmed by NMR and FTIR.In addition,size exclusion chromatography(SEC) results indicated that the copolymer had a symmetric peak and a relatively narrow polydispersity.Also,the random copolymers can self-assemble into micelle-like aggregates in water due to the hydrophilicity endowed by the amino groups,and the aggregates exhibited rich pH and GSH responsive behavior,which was verified by zeta masters instrument and dynamic light scattering(DLS).Moreover,transmission electron microscopy(TEM) demonstrated the morphology of the micellar aggregates and the variation subjected to the lower pH and GSH,and the responsive mechanism was elaborated.Therefore,these results highlighted a facile synthesis of the environment-responsive polymers and provided a novel GSH/pH responsive material platform for further application.

Effect of Long Chain Branching on the Rheological Behavior,Crystallization and Mechanical Properties of Polypropylene Random Copolymer

Long chain branched polypropylene random copolymers （LCB-PPRs） were prepared via reactive extrusion with the addition of dicumyl peroxide （DCP） and various amounts of 1,6-hexanediol diacrylate （HDDA） into PPR. Fourier transform infrared spectrometer （FTIR） was applied to confirm the existence of branching and（ investigate the grafting degree for the modified PPRs. Melt flow index （MFI） and oscillatory shear rheological properties including complex viscosity, storage modulus, loss tangent and the Cole-Cole plots were studied to differentiate the LCB-PPRs from linear PPR. Differential scanning calorimetry （DSC） and polarized light microscopy （PLM） were used to study the melting and crystallization behavior and the spherulite morphology, respectively. Qualitative and quantitative analyses of rheological curves demonstrated the existence of LCB. The effect of the LCB on crystalline morphology, crystallization behavior and molecular mobility, and, thereby, the mechanical properties were studied and analyzed. Due to the entanglements between molecular chains and the nucleating effect of LCB, LCB-PPRs showed higher crystallization temperature and crystallinity, higher crystallization rate, more uniformly dispersed and much smaller crystallite compared with virgin PPR, thus giving rise to significantly improve impact strength. Moreover, the LCB-PPRs exhibited the improved yield strength. The mobility of the molecular chain segments, as demonstrated by dynamic mechanical analysis （DMA）, was improved for the modified PPRs, which also contributed to the improvement of their mechanical properties.

Mechanism of Polymorph Selection during Crystallization of Random Butene-1/Ethylene Copolymer

Starting from an initial sample of butene-1/ethylene copolymer with stable form I＇, we examined the nucleation of different crystalline polymorphs （here metastable form II and stable form I＇） at different isothermal crystallization temperatures after being melted at different melt temperature （Tmelt）. When Tmelt was just above the melting temperature （Tm） of the crystallites, self-seeding took place. There, residue crystallites served as nuclei leading to the crystallization of the same crystalline phase. When Tmelt was a few degrees above the Tin, self-seeding was disabled due to complete melting of the initial crystals. Upon crystallization, the selection of the different polymorphs in this random copolymer was found to depend on an interplay between the domain size of segregated long crystallizable sequences and the size and energy barrier of the critical nucleus of the respective crystalline forms. Our results provide a clear understanding of the polymorphs selection during crystallization of a random copolymer as well as homo-polymers under confinement.

COMBINED EFFECT OF MODIFIED ZEOLITE 13X AND β-NUCLEATING AGENT ON IMPROVING β-CRYSTAL CONTENT AND TOUGHENING POLYPROPYLENE RANDOM COPOLYMER

Although addition of β-nucleating agent directly into homo-polypropylene （PPH） is a useful method to improve ,β-crystal content and toughen PPH, polypropylene random copolymer （PPR） makes this method powerless due to its random structure and low crystallinity. In this study, the β-nucleated PPR with high β-crystal content was prepared by a novel high effective β-nucleating system which consists of β-nucleation agent （TMB-5） and modified zeolite 13X （M13X）. It was found that M13X and TMB-5 had a synergistic influence on improving β-crystal content and toughening PPR. The content of β-crystal in PPR/M13X/TMB-5 was significantly larger than the sum of that in PPR/M13X and PPR/TMB-5. Besides, fracture behavior, phase morphology and relaxation of matrix chain segments were also investigated. The results showed that M13X and TMB-5 improved the mobility of amorphous chain segments at low temperature and contributed to much energy dissipation. This work provides a powerful method to modify PPR.

Enhanced Ultraviolet Resistance of Polypropylene Random Copolymer Filled by ZnO-supported Mesoporous Zeolite

To enhance the ultraviolet resistance of ZnO based polymer materials, ZnO-supported mesoporous zeolite（M-ZnO） was prepared and characterized by atomic absorption spectroscopy and scanning electron microscopy. The ultraviolet resistance, crystallization behavior and melting characteristics of ZnO and M-ZnO filled PPR composites were compared by FTIR spectra and differential scanning calorimetry. The ultraviolet resistance of M-ZnO filled PPR composites is higher than that of ZnO filled PPR composites, indicating higher ultraviolet resistance of M-ZnO than that of ZnO. The crystallization temperatures of mesoporous zeolite filled PPR were higher than those of M-ZnO and decreased with increasing UV-irradiation time. But the crystallization temperatures of M-ZnO filled PPR composites were not influenced by UV-irradiation time. The ZnO supported on the surface of zeolite is effective in enhancing the ultraviolet resistance of ZnO based polymer materials.

Preparation and Properties of Super-hydrophobic Surface by Fluorinated Copolymers

1 Rusults Fig.1 Surface morphologies of the PMMA-PFAEA copolymer filmsa-e, Random copolymer, a-e, synthesized by micro emulsion polymerization,a)b), MMA:FAEA=2:1, c) d), MMA:FAEA=5:1; e) synthesized by solution polymerization, MMA:FAEA=7:3; f) Block copolymer, synthesized by RAFT polymerization, MMA:FAEA=4:1, all solution concentration 1×10-2g/mL Super-hydrophobic surfaces have attracted significant attention recently, and various preparing methods have been reported. Besides these preparing methods, s...

Enhanced Mechanics in Injection Molded Isotactic Polypropylene/Polypropylene Random Copolymer Blends via Introducing Network-like Crystal Structure

The crystallization behavior, rheological behavior, mechanical properties and microstructures of injection molded isotactic polypropylene （iPP）, polypropylene random copolymer （co-PP） and iPP/co-PP blends were investigated. Differential scanning calorimetry （DSC） and dynamic rheological analysis illustrated that iPP and co-PP were compatible in the blends and co-PP uniformly dispersed in the/PP phase. Polarizing optical microscope （POM） was adopted to observe the crystal size and morphology evolution. The results of mechanical properties and scanning electron microscopy （SEM） indicated that the crystal size of iPP in iPP/co-PP blends （10 wt% co-PP ＋ 90 wt% iPP and 30 wt% co-PP ＋ 70 wt% iPP） radically decreased after the incorporation of co-PP. During crystallization, the molecular chain segments of co-PP could penetrate iPP spherulites and form a network-like crystalline structure. The network-like crystal structure could effectively transmit stress and consume more energy to overcome intermolecular forces to resist stretching. In this way, the strength would improve to a certain degree. The impact fracture mechanism of iPP/co-PP blends is quasi ductile fracture by multiple crazes. Our work discovered that the blends containing 10 wt% and 30 wt% ofco-PP exhibited prominent toughness and reinforcement.

Diketopyrrolopyrrole-based Conjugated Polymers as Additives to Optimize Morphology for Polymer Solar Cells

Novel random copolymers for optimizing the morphology of the active layer for high performance organic photovoltaic devices have been demonstrated. Three ternary random copolymers PTBDTDPPSiCN（3/7）, PTBDTDPPSiCN（5/5）, PTBDTDPPSiCN（7/3） were prepared by polymerization of electron-donating thienyl-substituted benzodithiophene （TBDT） with 2,5-bis[8-（1,1,3,3,5,5,5-heptamethyltrisiloxane-3-yl）octly]-pyrrolo[3,4-c]pyrrole-1,4-dione （DPPSi） and 2,5-dio[5-（5-cyano-5,5-dimethyl-pentyl）]-3,6-dithiophen-2-yl-pyrrolo[3,4-c]pyrrole-1,4-dione （DPPCN） of different ratios. The DPPCN block can well-tune the light absorption and molecular packing, while the DPPSi block is in favor of enhancing the charge mobility. And the formation of organic Si--O--Si networks is beneficial to stabilize the morphology of the active layer. These new copolymers have narrow bandgaps and broaden visible light absorption from 500 nm to 1000 nm. Careful balance of the contents of the trimethoxysilyl group and the cyano group can well-tune the surface energy and morphology of the copolymers. Incorporation of these novel copolymers as additives into the blend of poly（3-hexylthiophene） （P3HT） and [6,6]-phenyl-C60-butyric acid methyl ester （PC61BM） is found to effectively broaden the light absorption, improve the compatibility and morphology of the active layer. As a result, some devices with certain ratios of these copolymers as additives achieve the enhanced efficiency compared with the device based on pristine P3HT：PC61BM.

Ring-opening Copolymerization of ε-Caprolactone and δ-Valerolactone Catalyzed by a 2,6-Bis(amino)phenol Zinc Complex

In combination with methyllithium,a 2,6-bis(amino)phenol zinc complex 1 was used in the ring-opening polymerization ofδ-valerolactone in the absence or presence of benzyl alcohol and showed high efficiency,mainly producing cyclic and linear polyvalerolactones,respectively.On the basis of homopolymerization,the ring-opening copolymerization ofε-caprolactone andδ-valerolactone was investigated.The P(CL-co-VL)random copolymers,PCL-b-PVL and PVL-b-PCL diblock copolymers,were prepared by varying the feeding strategy(premixing or sequential feeding).The copolymer composition was adjusted by varying the feeding ratio of two monomers.The structure and thermal properties of obtained polymers were characterized by GPC,1 H-NMR,13 C-NMR,MALDI-TOF mass spectroscopy,and DSC,respectively.

Morphology and Properties of PP In-reactor Alloys Prepared with a MgCl2/TiCl4/Diisobutyl Phthalate/Phosphate Tris-methylphenyl Ester Catalyst System

A series of polypropylene（PP）/poly（ethylene-co-propylene） in-reactor alloys with different ethylene contents was prepared through a two-stage polymerization process using a MgCl2/TiCl4/diisobutyl phthalate/phosphate tris-methylphenyl ester catalyst system. The ethylene content, particle shape, fractured surface, and glass-transition temperature（Tg） of the obtained PP in-reactor alloys were characterized by means of nuclear magnetic resonance, scanning electron microscopy（SEM）, and dynamic mechamcal analysis（DMA）. The ethylene content of the PP alloys increased from 2.34% to 26.69% when the propylene/ethylene feed ratio was increased from 66/34 to 54/46（molar ratio）. Morevoer, the increment in ethylene content increased the notched Izod impact strength of the resulting PP alloys. The impact strength of the PP alloy with an ethylene content of 26.69% was 55.8 kJ/m^2, which is 12.7 times that of isotactic polypropylene. The results of DMA and SEM analysis reveal that ethylene-propylene random copolymer（EPR） in the PP alloy has a low Tg of ca. -50℃ and a high interface compatibility with the PP matrix. The excellent impact performance of the PP alloy can be attributed to the uniform dispersal of EPR in the alloy particles and PP matrix.