STUDIES ON SELF-ASSOCIATIVE BEHAVIOR OF A NOVEL CATION AMPHIPHILIC POLYMER

A novel associating polymer P(AEBA) was synthesized by radical polymerization of the cationic amphiphilic monomer,4-(2-(acryloyloxy)ethoxy)benzyl tri-ethyl ammonium bromide(AEBA),in aqueous solutions.P(AEBA) displays a strong tendency for self-association in aqueous solutions and is sensitive to the external stimulation such as added salt.The associative properties and morphologies of P(AEBA) were studied by fluorescnece probe technique,viscometry and TEM.In dilute salt-free solutions P(AEBA) behaves as pol...

Study of the reinforced mechanism of fly ash on amphiphilic polymer gel

Amphiphilic polymer gels are widely used in heterogeneous reservoirs for conformance control technology.However,in high temperature and high salinity of calcium and magnesium reservoirs,amphiphilic polymer gels cannot maintain effective performance.In this work,a novel reinforced amphiphilic polymer gel(F-PADC gel)was prepared by physically mixing polymer solution and fly ash(FA),which is an extremely low cost material.The viscoelasticity and stability of the F-PADC gel were studied by rheometry and micro-rheometry.The reinforced mechanism of FA on amphiphilic polymer gels was revealed.The results show that the addition of FA can make the gel more robust with a denser network structure.On the fifth day,the elastic modulus(G’)increases from 5.2 to 7.0 Pa and the viscosity modulus(G")increases from 0.4 to 0.6 Pa at the frequency of 1 Hz,which improves the viscoelasticity of the gel system.More importantly,the F-PADC gel does not degrade after aging at 85℃for 180 d.And its viscoelasticity increases obviously,G′and G"increase to 110.0 Pa and 3.5 Pa,respectively,showing excellent anti-aging stability.Moreover,FA amphiphilic polymer gels have a good injectivity and a perfect plugging rate of 98.86%,which is better than that of sole amphiphilic polymer gels.This novel mixed FA amphiphilic polymer gels can prove to be a better alternative to conventional polymer gels to enhance oil recovery in high temperature and high salinity reservoirs.

TWO DIMENSIONAL PROPERTIES OF REVERSED DUCKWEED AMPHIPHILIC POLYMER

The surface pressure-Area isotherms of Reversed Duckweed amphiphili polymer were examined in view of their chemical structure and two- dimentional properties of polymer monolayer were studied.

Controlled Fabrication of Uniform Digital Nanorods from Precise Sequence-Defined Amphiphilic Polymers in Aqueous Media

Compared with spherical micelles,rod/worm-like micelles not only have extended blood circulation duration,but also exhibit favorable cellular uptake behavior,which is promising for next-generation nanomedicine and biomaterials.However,the controllable fabrication of narrowly dispersed nanorods in aqueous media is still challenging.Herein,the methodology of thermal annealing was developed for the fabrication of helical nanorods as well as a series of nanorods with different lengths.The thermal annealing process generally consisted of adding a percentage of organic solvent(10%(V/V)or 20%(V/V))to the digital micellar aqueous dispersion,followed by heating at 90℃for 1 h,then cooling naturally to room temperature,and dialyzing against water to remove the organic solvent.Right-handed helical nanorods were afforded by the treatment of 45 nm digital micelles in the presence of 10%(V/V)dioxane,while left-handed helical nanorods were obtained in the presence of 20%(V/V)dioxane.Meanwhile,the controlled growth of rod-like digital micelles was achieved after thermal annealing in the presence of different types of organic solvents,and the length of the annealed nanorods was correlated with the types of organic solvent.Furthermore,no matter the size of initial digital micelles,they all exhibited similar trend of rod growth in the presence of a certain amount of organic solvent,allowing for controllable formulation of narrowly dispersed nanorods.In addition,supramolecular self-assembly by amphiphilic dendritic oligourethane readily fabricated diverse uniform nanorods in aqueous media.Overall,this work provided an attractive methodology to fabricate uniform digital nanorods.

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing Trans/Cis Isomers

Nanoporous membranes and vesicles are interesting systems with potential in applications offering channels for material exchange.Herein,nanoporous membranes and polymersomes are developed by self-assembly of trans-and cis-stereoisomers of amphiphilic polymers.Two polymers,PEG550-TPEChol and PEG550-SS-TPE-SS-Chol,containing a central tetraphenylethene(TPE),a cholesterol(Chol),and a poly(ethylene glycol)(PEG550)are studied.

CONTROLLED SYNTHESIS OF AMPHIPHILIC BLOCK POLYMERS HAVING GLUCOSE RESIDUES AND THEIR STRUCTURE FORMATION

Vinyl ether (VE)-based amphiphilic block copolymers with D-glucose residues as hydrophilicpendants were synthesized by CH_3 CH(OiBu)Cl/ZnI_2-initiated sequential living cationic copolymerization of3-O-(vinyloxy)ethyl-1, 2:5, 6-di-O-isopropylidene-D-glucofuranose (IGVE) and isobutyl VE (IBVE ) andsubsequent deprotection. The precursor block copolymers had a narrow molecular weight distribution(M_w/M_n～1.1) and a controlled segmental composition. The solubility characteristics of the amphiphiliccopolymer depended strongly on composition. Their solvent-cast thin films were examined, under atransmission electron microscope, and could be seen to exhibit various microphase-separated surfacemorphologies such as spheres, cylinders, and lamellae, depending on composition. The amphiphiliccopolymers with the appropriate segmental composition were found to form a stable monolayer at the air-water interface, which was successfully transferred onto a substrate by the Langmuir-Blodgett (LB)technique. The layered strucfure of the built-up LB films was controlled by blending the homopolymer.

Characterization of Fe_3O_4/P(St-MPEO) Amphiphilic Magnetic Polymer Microspheres

Amphiphilic magnetic microspheres consisting of styrene and poly(ethylene oxide) macromonomer(MPEO) were prepared by dispersion copolymerization in the presence of Fe_3O_4 magnetic fluid in an ethanol/water medium. The sizes of the magnetic microspheres and their distribution were characterized by means of scanning electron microscopy(SEM). The surface morphology and the average surface roughness of the microspheres were investigated by virtue of atomic force microscopy(AFM). It was found that the microspheres exhibit microscopic phase-separate and the mean square surface roughness of the microspheres increases with increasing MPEO used in the copolymerization. The amphiphilic magnetic microspheres containing 0 4-3 5 mg/g hydroxyl groups could be prepared from MPEO with different concentrations and styrene.

Amphiphilic Polyphosphazene with Poly(ethylene oxide) Side Chains Prepared through the Decker-Forster Reaction

Poly （4- methylphenoxyphosphnzene ） -graft-poly （ ethylene oxide ） （ PPZ-g- PEO ）, a novel amphiphilie grafting polymer was prepared via the Decker-Forster reaction. It is found that the graft efficiency increased with extension of reaction time. Low molecular weight of poly （ ethylene oxide ） favored the grafting reaction. The grafted polymer has two different glass transition temperatures（ Tg） with those of pure poly（ 4-methyl- phenoxy-phopsphazene ） and PEO. The emulsifying ability of grafted polymer was studied with benzene-water mixtare. The emulsifying volumes increased with the decreasing of PEO＇ s molecular weight. The contact angle of film forming from grafted polymer decreased after introduction of PEO grafting chain.

SYNTHESIS OF POLYBUTADIENE MACROINITIATOR AND POLYBUTADIENE/POLYACRYLAMIDE BLOCK COPOLYMERS

An azo-group containing polybutadiene macroinitiator was prepared by Pinner synthesis and characterized by IR, NMR, GPC, viscosity and elemental measurements. The macroinitiator was further use to polymerize acrylamide (AAm) in benzene to form polybutadiene/polyacrylamide (PBD/PAAm) block copolymers. High conversion of AAm was obtained over a wide range of monomer/macroinitiator ratios. The PBD/PAAm block copolymers were found to have excellent solvent resistance.

A General Approach for Synthesis of Circularly Assembled Supramolecular Polymers by Means of Region-confined Amphiphilic Supramolecular Polymerization

Topological supramolecular polymers are responsible for design of innovative materials with unique physical properties but remain a challenging task to prepare by means of supramolecular polymerization.In this contribution,we present a novel method of region-confined amphiphilic supramolecular polymerization(RASP)in a controllable two-step self-organization pathway,which was certified by a new type of pyridine-oxadiazole alternating 48-membered macrocycles with structurally regional distribution of distinct self-assembling groups that can self-organize into circular supramolecular architectures.Meanwhile,water molecule plays a crucial role in RASP,and the water content in nonpolar solvent chloroform is sensitive to trigger controllable amphiphilic self-organization.Moreover,differing from the traditional rodlike micelles formed by self-assembly of linearly amphiphilic molecules,this approach of RASP exclusively gives rise to the formation of circularly assembled supramolecular polymers.

Synthesis of a reduction-sensitive Bletilla striata polysaccharide amphiphilic copolymer

Recently, much special attention has been focused on the development of amphiphilic copolymers.Herein, a reduction-sensitive stearic acid grafted-Bletilla striata polysaccharide copolymer（BSP-ss-SA）was synthesized and characterized. BSP-ss-SA copolymer could spontaneously form micelles with an average particle size of（106 ？ 4.36） nm. Particle sizes were dramatically larger under 10 mmol/L dithiothreitol（DTT） than that in absence of 10 mmol/L DTT. Docetaxel loading content and encapsulation efficiency of micelles were 5.94 wt% and 72.75 wt%, respectively. The docetaxel release rate in vitro in micelles could be remarkably accelerated in pH 7.4 phosphate buffer solution（PBS） containing 10 mmol/L DTT compared with that of micelles（0 mmol/L DTT）. Furthermore, MTT results demonstrated the anticancer activities in vitro of docetaxel-loaded BSP-ss-SA micelles on HepG2 were superior to that of docetaxel injection. BSP-ss-SA copolymer might be a promising nanocarrier for cancer chemotherapy drugs.

Controlled Self-assembly of Thermo-responsive Amphiphilic H-shaped Polymer for Adjustable Drug Release

Despite the fact that some progress has been made in the self-assembly of H-shaped polymers, the corresponding self-assemblies that respond to external stimulus and are further utilized to adjust the release of drugs are still deficient. The stimuli-responsive segments with amphiphilic H-shaped structure are generally expected to enhance the controllability of self-assembly process. The synthesis and self-assembly behavior of thermo-responsive amphiphilic H-shaped polymers with poly（ethylene glycol） （PEG）, polytetrahydrofuran （PTHF） and poly（N-isopropyl acrylamide） （PNIPAM） as building blocks are reported in this paper. The inner architecture structure and size of complex micelles formed by H-shaped self-assemblies were effectively adjusted when the solution temperature was increased above the lower critical solution temperature of PNIPAM segments. Furthermore, it was found that the architecture of self-assemblies underwent a transition from the complex micelles based on primary micelles with hybrid PEG/PNIPAM shells to large complex micelles based on primary micelles with hybrid PTHF/PNIPAM cores and PEG shells during the thermal-induced self-assembly process. The adjustable release rate ofdoxorubicin （DOX） from the DOX-loaded complex micelles and basic cell experiments further proved the feasibility of these self-assemblies as the thermal-responsive drug delivery system.

Amphiphilic AIEgen-polymer aggregates:Design,self-assembly and biomedical applications

Aggregation-induced emission(AIE)is a phenomenon in which fluorescence is enhanced rather than quenched upon molecular assembly.AIE fluorogens(AIEgens)are flexible,conjugated systems that are limited in their dynamics when assembled,which improves their fluorescent properties.This intriguing feature has been incorporated in many different molecular assemblies and has been extended to nanoparticles composed of amphiphilic polymer building blocks.The integration of the fascinating AIE design principle with versatile polymer chemistry opens up new frontiers to approach and solve intrinsic obstacles of conventional fluorescent materials in nanoscience,including the aggregation-caused quenching effect.Furthermore,this integration has drawn significant attention from the nanomedicine community,due to the additional advantages of nanoparticles comprising AIEgenic molecules,such as emission brightness and fluorescence stability.In this regard,a range of AIEgenic amphiphilic polymers have been developed,displaying enhanced emission in the self-assembly/aggregated state.AIEgenic assemblies are regarded as attractive nanomaterials with inherent fluorescence,which display promising features in a biomedical context,for instance in biosensing,cell/tissue imaging and tracking,as well as(photo)therapeutics.In this review,we describe recent strategies for the design and synthesis of novel types of AIEgenic amphiphilic polymers via facile approaches including direct conjugation to natural/synthetic polymers,polymerization,post-polymerization and supramolecular host−guest interactions.Their self-assembly behavior and biomedical potential will be discussed.

SYNTHESIS OF POLYACRYLAMIDE WITH PENDANT POLY(BUTYL ACRYLATE) CHAINS USING THE MACROMER TECHNIQUE AND STUDIES ON THEIR PROPERTIES

An amphiphilic graft polymer, (PAM-g-PBA), polyacrylamide (PAM) having poly(n-butyl acrylate) (PBA) side chains, was obtained by radical copolymerization of acrylamide with PBA macromer in solution. The macromer was synthesized by free radical polymerization of butyl acrylate in the presence of different amounts of thioglycolic acid as the chain transfer agent, followed by termination with glycidyl methacrylate. The reactivity ratio and effects of copolymerization conditions on the conversion of macromer or grafting efficiency were studied. The crude products were purified by extraction with toluene and water successively. The purified graft copolymer was characterized by IR, DSC and TEM. PAM-g-PBA can bring about microphase separation and exhibits good emulsifying properties and water absorbency. PAM-g-PBA exhibits a very good compatibilizing effect on the acrylic rubber/poly(vinyl chloride) blends. 2%-3% of the graft copolymer is enough for enhancing the tensile strength of the blends. The tensile strength of the blends is more than twice that without the compatibilizer. DSC and SEM demonstrated the enhancement of compatibility in the presence of the graft copolymer.

Hyperbranched poly(ether amine)(hPEA)as novel backbone for amphiphilic one-component type-Ⅱ polymeric photoinitiators

To make photoinitiators （PI） to be polymeric and water-soluble is an effective approach to develop the high efficient photoinitiator systems with low-migration, low-toxic and environment-friend. We developed a series of novel amphiphilic hyperhranched polymeric photoinitiators （hPEA-TXs, and hPEA- BPs） by introducing thioxanthone （TX） or benzophenone （BP） moieties into the periphery of the hyperbranched poly（ether amine） （hPEA） comprised of the hydrophilic poly（ethylene oxide） （PEO） short chain and coinitiator amine moieties in the backbone. Compared with their water-soluble low-molecular weight analogues, the resulting hyperbranched polymeric photoinitiators hPEA101-TX, hPEA211-TX, hPEA101-BP and hPEA211-BP could be dissolved very well not only in many organic systems including acrylate monomers, but also in water with high solubility of 10 wt~. The photopolymerization kinetics of water-soluble monomer acrylamide （AM） and three hydrophobic multifunctional acrylate monomers initiated by these hyperbranched photoinitiators were investigated in detail by photo-differential scanning calorimetric （photo-DSC）. Both hPEA-TXs and hPEA-BPs can initiate photopolymerization of AM as efficiently as their low-molecular weight analogues MGA-TX and MGA-BP, respectively. The final double bond conversion （DBC） of oil-soluble monomer hexanediol diacrylate （HDDA） photoinitiated by these hyperbranched photoinitiators can reach as high as 99%. Especially for photopolymerization of multifunctional monomers initiated by these hyperbranched polymeric photoinitiators, the final DBC of trimethylolpropane triacrylate （TMPTA） and pentaerythritol tetraacrylate （PETTA） can reach 80% and 60%, respectively, which is much higher than that of low-molecular weight photoinitiators.

Amphiphilic hyperbranched polymers:synthesis,characterization and selfassembly performance

A series of amphiphilic hyperbranched polymers(AHP-s,the“s”refers to the algebra of AHP)were synthesized by the reaction between hydroxyl-terminated hyperbranched polymers(HBP-s,the“s”refers to the algebra of HBP)and palmitoyl chloride.FTIR,NMR and GPC were used to determine the structure of AHP-s,the results showed that AHP-s exhibits core-shell structure.The thermal properties of polymers were investigated by DSC and TGA.It was found that AHP-2,AHP-3 and AHP-4 display higher thermal stability than AHP-1(AHP-1,AHP-2,AHP-3 and AHP-4 represent the first,second,third and fourth generation AHP,respectively).Furthermore,the self-assembly performance of AHP-s in THF solvent was investigated by TEM and SEM.Finally,the encapsulation capacity of the AHP-s for methyl orange(MO)was explored at different concentrations of AHP-s and pH conditions.It was found that AHP-s is capable of accommodating hydrophilic guest MO.Moreover,the higher generation of AHP-s,the stronger encapsulation capacity obtained.And the encapsulation capacity closely associated with the pH of encapsulation system.

Polymeric dual-modal imaging nanoprobe with two-photon aggregation-induced emission for fluorescence imaging and gadolinium-chelation for magnetic resonance imaging

Nanoprobes that offer both fluorescence imaging(FI)and magnetic resonance imaging(MRI)can provide supplementary information and hold synergistic advantages.However,synthesis of such dual-modality imaging probes that simultaneously exhibit tunability of functional groups,high stability,great biocompatibility and desired dual-modality imaging results remains challenging.In this study,we used an amphiphilic block polymer from(ethylene glycol)methyl ether methacrylate(OEGMA)and N-(2-hydroxypropyl)methacrylamide(HPMA)derivatives as a carrier to conjugate a MR contrast agent,Gd-DOTA,and a two-photon fluorophore with an aggregation-induced emission(AIE)effect,TPBP,to construct a MR/two-photon fluorescence dual-modality contrast agent,Gd-DOTA-TPBP.Incorporation of gadolinium in the hydrophilic chain segment of the OEGMA-based carrier resulted in a high r_(1)value for Gd-DOTA-TPBP,revealing a great MR imaging resolution.The contrast agent specifically accumulated in the tumor region,allowing a long enhancement duration for vascular and tumor contrast-enhanced MR imaging.Meanwhile,coupling TPBP with AIE properties to the hydrophobic chain segment of the carrier not only improved its water solubility and reduced its cytotoxicity,but also significantly enhanced its imaging performance in an aqueous phase.Gd-DOTA-TPBP was also demonstrated to act as an excellent fluorescence probe for two-photon-excited bioimaging with higher resolution and greater sensitivity than MRI.Since high-resolution,complementary MRI/FI dual-modal images were acquired at both cellular and tissue levels in tumor-bearing mice after application of Gd-DOTA-TPBP,it has great potential in the early phase of disease diagnosis.

Dissipative Particle Dynamics Study on Aggregation of MPEG- PAE-PLA Block Polymer Micelles Loading Doxorubicine

To guide the molecular design of the pH-sensitive triblock amphiphilic polymer MPEG-PAE-PLA and the for- mula design of its doxorubicine （DOX）-loaded micelles, dissipative particle dynamics （DPD） simulations are em- ployed to investigate the aggregation behaviors of the DOX-loaded micelles. The simulation results showed that the aggregate morphologies of micelles and DOX distribution are influenced by degree of polymerization of blocks, and the proposed structure of polymer is MPEG44-PAE3-PLA4. With different contents of polymer or DOX, differ- ent aggregate morphologies of the micelles, like microsphere, spindle/column, reticulation or lamella are observed. To prepare the micro-spherical DOX-loaded micelles, the polymer content is proposed as 10%--15%, and the DOX content less than 10%.

Folate-conjugated pH-responsive nanocarrier designed for active tumor targeting and controlled release of doxorubicin

A novel type of amphiphilic pH-responsive folate-poly（ε-caprolactone）- block-poly（ 2-hydroxyethylmethacrylate ）-co-poly（ 2-（ dimethylamino ）-ethylmethacrylate ） （FA-PCL-b-P（HEMA-co-DMAEMA）） （MFP） block copolymers were designed and synthe- sized via atom transfer radical polymerization （ATRP） and ring opening polymerization （ROP） techniques. The molecular structures of the copolymers were confirmed with IH NMR, FTIR and GPC measurements. The critical micelle concentration （CMC） of MFP in aqueous solution was extremely low （about 6.54 mglL）. The in vitro release behavior of DOX-Ioaded micelles was significantly accelerated when the pH value of solution decreased from 7.4 to 5.0. In vitro antitumor efficiency was evaluated by incubating DOX- loaded micelles with Hela cells. The results demonstrated that this copolymer possessed excellent biocompatibility, and FA-decorated micelles MFP showed higher cellular uptake than those micelles without the FA moiety, indicating their unique targetability. These folate-conjugated biodegradable micelles are highly promising for targeted cancer chemothe-rapy.