可还原降解梳形阳离子聚合物的合成

通过缩合聚合和可逆加成-断裂链转移聚合(RAFT)合成了一种新型可还原降解的梳形聚阳离子.首先,以具有化学选择性的三氟甲磺酸钪催化苹果酸、二硫二丙酸、癸二醇的三元缩合聚合得到了含多个侧羟基的聚(苹果酸-co-二硫二丙酸)癸二酯;将羟基酯化修饰为双硫酯后,通过甲基丙烯酸二甲氨基乙酯(DMAEMA)的RAFT聚合制备了梳型聚甲基丙烯酸二甲氨基乙酯(PDMAEMA).采用1H-NMR和GPC等测试方法对该聚合物进行结构表征.该梳形阳离子聚合物在还原性环境中可通过双硫键的断裂降解成为小分子量PDMAEMA低聚物.     

Synthesis,self‐assembly,fluorescence, and thermosensitive properties of star‐shaped amphiphilic copolymers with porphyrin core

Star‐shaped amphiphilic poly(ε‐caprolactone)‐block‐poly(oligo(ethylene glycol) methyl ether methacrylate) with porphyrin core (SPPCL‐b‐POEGMA) was synthesized by combination of ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Star‐shaped PCL with porphyrin core (SPPCL) was prepared by bulk polymerization of ε‐caprolactone (CL) with tetrahydroxyethyl‐terminated porphyrin initiator and tin 2‐ethylexanote (Sn(Oct)₂) catalyst. SPPCL was converted into SPPCLBr macroinitiator with 2‐bromoisobutyryl bromide. Star‐shaped SPPCL‐b‐POEGMA was obtained via ATRP of oligo(ethylene glycol) methyl ether methacrylate (OEGMA). SPPCL‐b‐POEGMA can easily self‐assemble into micelles in aqueous solution via dialysis method. The formation of micellar aggregates were confirmed by critical micelle formation concentration, dynamic light scattering, and transmission electron microscopy. The micelles also exhibit property of temperature‐induced drug release and the lower critical solution temperature (LCST) was 60.6 °C. Furthermore, SPPCL‐b‐POEGMA micelles can reversibly swell and shrink in response to external temperature. In addition, SPPCL‐b‐POEGMA can present obvious fluorescence. Finally, the controlled drug release of copolymer micelles can be achieved by the change of temperatures. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A facile method of forming nanoscale patterns on poly(ethylene glycol)-based surfaces by self-assembly of randomly grafted block copolymer brushes

Poly(oligo(ethylene glycol) methacrylate) (POEGMA) block poly(methyl methacrylate) (PMMA) brushes were synthesized on the silicon wafer surfaces by the surface-initiated atom transfer radical polymerization (ATRP) method. Atomic force microscopy, ellipsometry, and water contact angle methods were employed to study the surface morphology and stimulus-response behavior. It was found that simple solvent treatments could induce phase segregation of the POEGMA and PMMA segments thus introducing nanoscale patterns. The feature size could be less than 10 nm and was tunable on the nanoscale. Various patterns including spherical aggregates, wormlike aggregates, stripe patterns, perforated layers, and complete overlayers were obtained through adjusting the upper block layer thickness. These patterns could switch between the different morphologies reversibly after the treatment with selective solvents.     

Well‐defined succinylated chitosan‐O‐poly(oligo(ethylene glycol)methacrylate) for pH‐reversible shielding of cationic nanocarriers

A novel type of well‐defined graft copolymer, succinylated chitosan‐O‐poly(oligo(ethylene glycol)methacrylate) (SC‐POEGMA), was developed for pH‐reversible poly(ethylene glyocol) (PEG) shielding of cationic nanocarriers. Chitosan‐O‐POEGMA (CS‐POEGMA) was first synthesized via single electron transfer‐living radical polymerization of oligo(ethylene glyol) methacrylate (OEGMA) using O‐brominated chitosan (CS‐Br) as a macromolecular initiator and Cu(I)Br/1,1,4,7,10,10‐hexamethyltriethylenetetramine as a catalyst. The subsequent succinylation of the chitosan backbone gave the titled copolymers. The content of POEGMA in CS‐POEGMA could be widely modulated by varying the degree of bromination and feed ratio of OEGMA to CS‐Br, without compromising the amino density of chitosan backbone. The hierarchical assembly between SC‐POEGMA and trimethylated chitosan‐O‐poly(ε‐caprolactone) (TMC‐PCL) micelles was further studied. At pH 7.4, the stoichiometric interactions between SC and TMC segments to form polyampholyte–polyelectrolyte complexes led to the formation of PEG‐shielded micelles. The hierarchially assembled micelles could be disassembled into the pristine TMC‐PCL micelles, when the medium pH was below a certain pH (pH_φ). By varying the degree of succinylation of SC‐POEGMA, the pH_φ value could be facilely modulated from 6.5 to 3.5 to meet the needs for specific biomedical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A library of thermoresponsive PEG-based methacrylate homopolymers: How do the molar mass and number of ethylene glycol groups affect the cloud point?

In this study, a novel library of thermoresponsive homopolymers based on poly (ethylene glycol) (EG) (m)ethyl ether methacrylate monomers is presented. Twenty-seven EG based homopolymers were synthesized and three parameters, the molar mass (MM), the number of the ethylene glycol groups in the monomer, and the chemistry of the functional side group were varied to investigate how these affect their thermoresponsive behavior. The targeted MMs of these polymers are varied from 2560, 5000, 8200 to 12,000 g mol⁻¹. Seven PEG-based monomers were investigated: ethylene glycol methyl ether methacrylate (MEGMA), ethylene glycol ethyl ether methacrylate (EEGMA), di(ethylene glycol) methyl ether methacrylate (DEGMA), tri(ethylene glycol) methyl ether methacrylate (TEGMA), tri(ethylene glycol) ethyl ether methacrylate (TEGEMA), penta(ethylene glycol) methyl ether methacrylate (PEGMA), nona(ethylene glycol) methyl ether methacrylate (NEGMA). Homopolymers of 2-(dimethylamino) ethyl methacrylate (DMAEMA) were also synthesized for comparison. The cloud points of these homopolymers were tested in different solvents and it was observed that it decreases as the number of EG group was decreased or the MM increased. Interestingly, the end functional group (methoxy or ethoxy) of the side group has an effect as well and is even more dominant than the number of EG groups.     

PLMA‐b‐POEGMA amphiphilic block copolymers: Synthesis and self‐assembly in aqueous media

The synthesis and self‐assembly properties in aqueous solutions of novel amphiphilic block copolymers composed of one hydrophobic poly (lauryl methacrylate), (PLMA) block and one hydrophilic poly (oligo ethylene glycol methacrylate) (POEGMA) block are reported. The block copolymers were prepared by RAFT polymerization and were molecularly characterized by size exclusion chromatography, NMR and FT‐IR spectroscopy, and DSC. The PLMA‐b‐POEGMA amphiphilic block copolymers self‐assemble in nanosized complex nanostructures resembling compound micelles when inserted in aqueous media, as supported by light scattering and TEM measurements. The encapsulation and release of the model, hydrophobic, nonsteroidal anti‐inflammatory drug indomethacin in the polymeric micelles is also investigated. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 155–163     

易衍生化温敏高分子刷的制备及其温敏行为研究

温敏材料由于优异的性能和潜在的应用价值而具有良好的发展前景.利用超分子自组装单层(SAM)与表面引发聚合(SIP)技术将2-(2-甲氧乙氧基)甲基丙烯酸乙酯(MEO2MA)与聚乙二醇甲基丙烯酸酯(OEGMA526)的共聚物poly(MEO2MAco-OEGMA526)接枝于金表面,探索了不同引发剂溶液浓度(χIsol)、单体OEGMA526摩尔浓度(C526)与干态膜厚度(d)对该高分子刷性质的影响.应用石英晶体微天平(QCM)对其温敏行为进行研究,结果表明:在χIsol=1%与C526=5%条件下制备的高分子刷,最低临界溶解温度(LCST)为34℃;其LCST由OEGMA526的单体摩尔浓度决定,不受膜厚的影响.该高分子刷在接枝生物素后其与链霉亲和素的结合实验证明,高分子刷末端的羟基为其官能团化提供了契机.该易衍生化温敏高分子刷为发展新型温敏材料提供了研究基础.     

Solution properties of well-defined 2-(dimethylamino)ethyl methacrylate-based (co)polymers: A viscometric approach

Well-defined poly(2-(dimethylamino)ethyl methacrylate)-based (co)polymers with various molar masses were synthesized by atom transfer radical polymerization (ATRP) using CuBr ligated with 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) as catalyst, and ethyl 2-bromoisobutyrate (EBiB) or α-methyl, ω-(2-bromoisobutyrate) poly(ethylene glycol) (mPEG_x-BiB) as (macro)initiator. The solution properties of these (co)polymers were investigated by viscometry either in pure water or in concentrated buffer solutions. It comes out that reduced viscosity in pure water is strongly affected by the molar mass of poly(2-(dimethylamino)ethyl methacrylate) block but also by the quaternization degree of tertiary amino groups. In fact, a polyelectrolyte effect can only be detected when the charge density per macromolecule reaches a critical value either in terms of molar mass or quaternization degree. Fitting of viscometry data according to either Huggins or Fuoss and Fedors equation also allows calculating the intrinsic viscosity and approaching the overlap concentration.     

Point by point comparison of two thermosensitive polymers exhibiting a similar LCST: is the age of poly(NIPAM) over?

The present Communication compares the thermosensitivity in dilute aqueous solutions of well-defined copolymers composed of 95% of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and 5% of oligo(ethylene glycol) methacrylate (OEGMA, Mn = 475 g.mol-1) and poly(N-isopropylacrylamide) (PNIPAM) samples having similar degrees of polymerization and chain-ends. The thermoresponsive behavior of P(MEO2MA-co-OEGMA) was found to be overall comparable, and in some cases, superior to PNIPAM. Hence, P(MEO2MA-co-OEGMA) copolymers can be considered as ideal structures, which combine both the properties of poly(ethylene glycol) and PNIPAM in a single macromolecule.     

Synthesis and characterization of novel pH-responsive microgels based on tertiary amine methacrylates

Emulsion polymerization of 2-(diethylamino)ethyl methacrylate (DEA) in the presence of a bifunctional cross-linker at pH 8-9 afforded novel pH-responsive microgels of 250-700 nm diameter. Both batch and semicontinuous syntheses were explored using thermal and redox initiators. Various strategies were evaluated for achieving colloidal stability, including charge stabilization, surfactant stabilization, and steric stabilization. The latter proved to be the most convenient and effective, and three types of well-defined reactive macromonomers were examined, namely, monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA), styrene-capped poly[2-(dimethylamino)ethyl methacrylate] (PDMA50-St), and partially quaternized styrene-capped poly[2-(dimethylamino)ethyl methacrylate] (10qPDMA50-St). The resulting microgels were pH-responsive, as expected. Dynamic light scattering and 1H NMR studies confirmed that reversible swelling occurred at low pH due to protonation of the tertiary amine groups on the DEA residues. The critical pH for this latex-to-microgel transition was around pH 6.5-7.0, which corresponds approximately to the known pKa of 7.0-7.3 for linear PDEA homopolymer. The microgel particles were further characterized by electron microscopy and aqueous electrophoresis studies. Their swelling and deswelling kinetics were investigated by turbidimetry. The PDEA-based microgels were compared to poly[2-(diisopropylamino)ethyl methacrylate] (PDPA) microgels prepared with identical macromonomer stabilizers. These PDPA-based microgels had a lower critical swelling pH of around pH 5.0-5.5, which correlates with the lower pKa of PDPA homopolymer. In addition, the kinetics of swelling for the PDPA microgels was somewhat slower than that observed for PDEA microgels; presumably this is related to the greater hydrophobic character of the former particles.     

Water-soluble organo-silica hybrid nanotubes templated by cylindrical polymer brushes

We report the preparation of water-soluble organo-silica hybrid nanotubes templated by core-shell-corona structured triblock terpolymer cylindrical polymer brushes (CPBs). The CPBs consist of a polymethacrylate backbone, a poly(tert-butyl acrylate) (PtBA) core, a poly(3-(trimethoxysilyl)propyl acrylate) (PAPTS) shell, and a poly(oligo(ethylene glycol) methacrylate) (POEGMA) corona. They were prepared via the "grafting from" strategy by the combination of two living/controlled polymerization techniques: anionic polymerization for the backbone and atom transfer radical polymerization (ATRP) for the triblock terpolymer side chains. The monomers tBA, APTS, and OEGMA were consecutively grown from the pendant ATRP initiating groups along the backbone to spatially organize the silica precursor, the trimethoxysilyl groups, into a tubular manner. The synthesized core-shell-corona structured CPBs then served as a unimolecular cylindrical template for the in situ fabrication of water-soluble organo-silica hybrid nanotubes via base-catalyzed condensation of the PAPTS shell block. The formed tubular nanostructures were characterized by transmission electron microscopy (TEM), cryogenic TEM, and atomic force microscopy.     

Novel antifouling oligo(ethylene glycol) methacrylate particles via surfactant-free emulsion polymerization

The use of particle formulations with antifouling surface properties attracts increasing interest in several biotechnological applications. Majority of these studies utilize a poly(ethylene glycol) coating to render the corresponding surface nonrecognizable to biological macromolecules. Herein, we report a simple way to prepare novel antifouling colloids composed of oligo(ethylene glycol) backbones via surfactant-free emulsion polymerization. Monodisperse cross-linked poly(ethylene glycol) ethyl ether methacrylate particles were characterized by dynamic light scattering and transmission electron microscopy. The effects of monomer, cross-linker and initiator on particle characteristics were investigated. More importantly, a prominent blockage of bovine serum albumin adsorption was obtained for the poly(ethylene glycol)-based sub-micron (~200 nm) particles when compared with similar-sized poly(methyl methacrylate) counterparts.     

Thermoresponsive PPEGMEA‐g‐PPEGEEMA well‐defined double hydrophilic graft copolymer synthesized by successive SET‐LRP and ATRP

A series of well‐defined double hydrophilic graft copolymers containing poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) backbone and poly[poly(ethylene glycol) ethyl ether methacrylate] (PPEGEEMA) side chains were synthesized by the combination of single electron transfer‐living radical polymerization (SET‐LRP) and atom transfer radical polymerization (ATRP). The backbone was first prepared by SET‐LRP of poly(ethylene glycol) methyl ether acrylate macromonomer using CuBr/tris(2‐(dimethylamino)ethyl)amine as catalytic system. The obtained comb copolymer was treated with lithium diisopropylamide and 2‐bromoisobutyryl bromide to give PPEGMEA‐Br macroinitiator. Finally, PPEGMEA‐g‐PPEGEEMA graft copolymers were synthesized by ATRP of poly(ethylene glycol) ethyl ether methacrylate macromonomer using PPEGMEA‐Br macroinitiator via the grafting‐from route. The molecular weights of both the backbone and the side chains were controllable and the molecular weight distributions kept narrow (M_w/M_n ≤ 1.20). This kind of double hydrophilic copolymer was found to be stimuli‐responsive to both temperature and ion (0.3 M Cl^? and SO). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 647–655, 2010     

pH-responsive capsules derived from nanocrystal templating

In the current work we demonstrate a facile and versatile way to create hydrophilic polymeric capsules by integration of Au nanocrystal templating, surface-initiated atom-transfer radical polymerization, and selective chemical cross-linking of polymer shells. Capsules of the homopolymer of 2-(dimethylamino)ethyl methacrylate and its copolymers with 2-(diethylamino)ethyl methacrylate and poly(ethylene glycol) methyl ether methacrylate were constructed. They swell at low pH and shrink at high pH. On the basis of the pH sensitivity of the resulting capsules, encapsulation and release of a drug model, rhodamine 6G, were realized. Furthermore, by cleaving Au-S bonds between Au cores and polymer shells, capsules containing free Au cores were generated, paving a simple pathway to introduce more functionality to the polymeric capsules.     

Novel copolymer networks via the combination of polyaddition and anionic polymerization

A two‐step synthetic route to novel copolymer networks, consisting of polymethacrylate and polyacetal components, was developed by combining the polyaddition and anionic polymerization techniques. The functional polymethacrylates containing hydroxyl or vinyloxyl side groups were used as crosslinkers. They were anionically synthesized as follows: the copolymer of 2‐hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) was prepared by the anionic copolymerization of 2‐(trimethylsiloxy)ethyl methacrylate and MMA, followed by hydrolysis. The copolymer poly(HEMA‐co‐MMA) thus obtained possessed a hydroxyl group in each of its HEMA units. Another kind of vinyloxyl‐containing (co)polymer was prepared by the anionic homopolymerization of 2‐(vinyloxy)ethyl methacrylate (VEMA) or its copolymerization with MMA. The resulting (co)polymer possessed reactive vinyloxyl side groups. The copolymer networks were obtained by reacting each of the above‐mentioned (co)polymers with a polyacetal prepared via the polyaddition between a divinyl ether and a diol. Three divinyl ethers (ethylene glycol divinyl ether, 1,4‐butanediol divinyl ether, and 1,6‐hexanediol divinyl ether) and three diols (ethylene glycol, 1,4‐butanediol, and 1,6‐hexanediol) were employed as monomers in the polyaddition step, and their combinations generated nine kinds of polyacetals. When a polyaddition reaction was terminated with a divinyl ether monomer, a polyacetal with two vinyloxyl end groups was obtained, which could further react with the hydroxyl groups of poly(HEMA‐co‐MMA) to generate a copolymer network. On the other hand, when a diol was used as terminator in the polyaddition, the resulting polyacetal possessed two hydroxyl end groups, which could react with the vinyloxyl groups of poly(VEMA) or poly(VEMA‐co‐MMA), to generate a copolymer network. All the copolymer networks exhibited degradation in the presence of acids. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 117–126, 2001     

Coffee Beverage: A New Strategy for the Synthesis of Polymethacrylates via ATRP

Coffee, the most popular beverage in the 21st century society, was tested as a reaction environment for activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) without an additional reducing agent. Two blends were selected: pure Arabica beans and a proportional blend of Arabica and Robusta beans. The use of the solution received from the mixture with Robusta obtained a high molecular weight polymer product in a short time while maintaining a controlled structure of the synthesized product. Various monomers with hydrophilic characteristics, i.e., 2-(dimethylamino)ethyl methacrylate (DMAEMA), oligo(ethylene glycol) methyl ether methacrylate (OEGMA₅₀₀), and glycidyl methacrylate (GMA), were polymerized. The proposed concept was carried out at different concentrations of coffee grounds, followed by the determination of the molar concentration of caffeine in applied beverages using DPV and HPLC techniques.     

Solvent-free synthesis and purification of poly[2-(dimethylamino)ethyl methacrylate] by atom transfer radical polymerization

Solvent-free synthesis of well-defined poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) (co)polymers was performed by atom transfer radical polymerization conducted under very mild conditions (in bulk at 25 degrees C). The pH-dependence and the thermo-responsive behaviour of PDMAEMA in aqueous solution were operated to isolate and purify the (co)polymers without using any organic solvent or further catalyst extraction. The viscosity in aqueous solution of so-purified PDMAEMA homopolymers and their block copolymers with poly(ethylene glycol) (PEG) was studied as a function of molar mass and concentration and a typical polyelectrolyte behaviour was observed, these catalyst-deprived polycations are able to form stable and non toxic complexes with DNA, showing good transfection efficacies in gene therapy.     

Atom transfer radical polymerization directly from poly(vinylidene fluoride): Surface and antifouling properties

The direct preparation of grafting polymer brushes from commercial poly (vinylidene fluoride) (PVDF) films with surface‐initiated atom transfer radical polymerization (ATRP) is demonstrated. The direct initiation of the secondary fluorinated site of PVDF facilitated grafting of the hydrophilic monomers from the PVDF surface. Homopolymer brushes of 2‐(N,N‐dimethylamino)ethyl methacrylate (DMAEMA) and poly (ethylene glycol) monomethacrylate (PEGMA) were prepared by ATRP from the PVDF surface. The chemical composition and surface topography of the graft‐functionalized PVDF surfaces were characterized by X‐ray photoelectron spectroscopy, attenuated total reflectance/Fourier transform infrared spectroscopy, and atomic force microscopy. A kinetic study revealed a linear increase in the graft concentration of poly[2‐(N,N‐dimethylamino)ethyl methacrylate] (PDMAEMA) and poly[poly(ethylene glycol) monomethacrylate] (PPEGMA) with the reaction time, indicating that the chain growth from the surface was consistent with a controlled or living process. The living chain ends were used as macroinitiators for the synthesis of diblock copolymer brushes. The water contact angles on PVDF films were reduced by the surface grafting of DMAEMA and PEGMA. Protein adsorption experiments revealed a substantial antifouling property of PPEGMA‐grafted PVDF films and PDMAEMA‐grafted PVDF films in comparison with the pristine PVDF surface. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3434–3443, 2006     

Film-forming microgels for pH-triggered capture and release

The pH-responsive behavior for a series of lightly cross-linked, sterically stabilized poly(tertiary amine methacrylate)-based latexes adsorbed onto mica and silica was investigated using in situ tapping mode AFM at room temperature. The adsorbed layer structure was primarily determined by the glass transition temperature, T(g), of the latex: poly[2-(diethylamino)ethyl methacrylate]-based particles coalesced to form relatively featureless uniform thin films, whereas the higher T(g) poly[2-(diisopropylamino)ethyl methacrylate] latexes retained their original particulate character. Adsorption was enhanced by using a cationic poly[2-(dimethylamino)ethyl methacrylate] steric stabilizer, rather than a nonionic poly(ethylene glycol)-based stabilizer, since the former led to stronger electrostatic binding to the oppositely charged substrate. Both types of adsorbed latexes acquired cationic microgel character and swelled appreciably at low pH, even those that had coalesced to form films. Fluorescence spectroscopy was used to study the capture of a model hydrophobic probe, pyrene, by these adsorbed latex layers followed by its subsequent release by lowering the solution pH. The repeated capture and release of pyrene through several pH cycles was also demonstrated. Since these poly(tertiary amine methacrylate) latexes are readily prepared by aqueous emulsion polymerization and adsorption occurs spontaneously from aqueous solution, this may constitute an attractive route for the surface modification of silica, mica and other oxides.     

Dual‐responsive supramolecular inclusion complexes of block copolymer poly(ethylene glycol)‐block‐poly[(2‐dimethylamino)ethyl methacrylate] with α‐cyclodextrin

A new class of temperature and pH dual‐responsive and injectable supramolecular hydrogel was developed, which was formed from block copolymer poly(ethylene glycol)‐block‐poly[(2‐dimethylamino)ethyl methacrylate] (PEG‐b‐PDMAEMA) and α‐cyclodextrin (α‐CD) inclusion complexes (ICs). The PEG‐b‐PDMAEMA diblock copolymers with different ratio of ethylene glycol (EG) to (2‐dimethylamino)ethyl methacrylate (DMAEMA) (102:46 and 102:96, respectively) were prepared by atom transfer radical polymerization (ATRP). ¹H NMR measurement indicated that the ratio of EG unit to α‐CD in the resulted ICs was higher than 2:1. Thermal analysis showed that thermal stability of ICs was improved. The rheology studies showed that the hydrogels were temperature and pH sensitive. Moreover, the hydrogels were thixotropic and reversible. The self‐assembly morphologies of the ICs in different pH and ionic strength environment were studied by transmission electron microscopy. The formed biocompatible micelles have potential applications as biomedical and stimulus‐responsive material. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2143–2153, 2010