HPLC analysis of synthetic polymers on short monolithic columns

Ultrashort monolithic columns (disks) were thoroughly studied as efficient stationary phases for precipitation–dissolution chromatography of synthetic polymers. Gradient elution mode was applied in all chromatographic runs. The mixtures of different flexible chain homopolymers, such as polystyrenes, poly(methyl methacrylates), and poly(tert‐butylmethacrylates) were separated according to their molecular weights on both commercial poly(styrene‐co‐divinylbenzene) disks (12 id × 3 mm and 5 × 5 mm) and lab‐made monolithic columns (4.6 id × 50 mm) filled with supports of different hydrophobicity. The experimental conditions were optimized to reach fast and highly efficient separation. It was observed that, similar to the separation of monoliths of other classes of (macro)molecules (proteins, DNA, oligonucleotides), the length of column did not affect the peak resolution. A comparison of the retention properties of the poly(styrene‐co‐divinylbenzene) disk‐shaped monoliths with those based on poly(lauryl methacrylate‐co‐ethylene dimethacrylate), poly(butyl methacrylate‐co‐ethylene dimethacrylate), and poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) supports demonstrated the obvious effect of surface chemistry on the resolution factor. Additionally, the results of the discussed chromatographic mode on the fast determination of the molecular weights of homopolymers used in this study were compared to those established by SEC on columns packed with sorbent beads of a similar nature to the monoliths.     

Hydrophobic‐hydrophilic monolithic dual‐phase layer for two‐dimensional thin‐layer chromatography coupled with surface‐enhanced Raman spectroscopy detection

Hydrophobic‐hydrophilic monolithic dual‐phase plates have been prepared by a two‐step polymerization method for two‐dimensional thin‐layer chromatography of low‐molecular‐weight compounds, namely, several dyes. The thin 200 μm poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) layers attached to microscope glass plates were prepared using a UV‐initiated polymerization method within a simple glass mold. After cutting and cleaning the specific area of the layer, the reassembled mold was filled with a polymerization mixture of butyl methacrylate and ethylene dimethacrylate and subsequently irradiated with UV light. During the second polymerization process, the former layer was protected from the UV light with a UV mask. After extracting the porogens and hydrolyzing the poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) area, these two‐dimensional layers were used to separate a mixture of dyes with great difference in their polarity using reversed‐phase chromatography mode within the hydrophobic layer and then hydrophilic interaction chromatography mode along the hydrophilic area. In the latter dimension only the specific spot was developed further. Detection of the separated dyes could be achieved with surface‐enhanced Raman spectroscopy.     

Comparative evaluation of a one‐pot strategy for the preparation of β‐cyclodextrin‐functionalized monoliths: Effect of the degree of amino substitution of β‐cyclodextrin on the column performance

To further evaluate the feasibility and applicability of the one‐pot strategy in monolithic column preparation, two novel β‐cyclodextrin‐functionalized organic polymeric monoliths were prepared using two β‐cyclodextrin derivatives, i.e. mono(6‐amino‐6‐deoxy)‐β‐cyclodextrin and heptakis(6‐amino‐6‐deoxy)‐β‐cyclodextrin. In this improved method, mono(6‐amino‐6‐deoxy)‐β‐cyclodextrin or heptakis(6‐amino‐6‐deoxy)‐β‐cyclodextrin reacted with glycidyl methacrylate to generate the corresponding functional monomers and were subsequently copolymerized with ethylene dimethacrylate. The polymerization conditions for both monoliths were carefully optimized to obtain satisfactory column performance with respect to column efficiency, reproducibility, permeability, and stability. The obtained poly(glycidyl methacrylate‐mono(6‐amino‐6‐deoxy)‐β‐cyclodextrin‐co‐ethylene dimethacrylate) and poly(glycidyl methacrylate‐heptakis(6‐amino‐6‐deoxy)‐β‐cyclodextrin‐co‐ethylene dimethacrylate) monoliths exhibited a uniform structure, good permeability, and mechanical stability as indicated by scanning electron microscopy and micro‐high‐performance liquid chromatography experimental results. Because of the probable existence of multi‐glycidyl methacrylate linking spacers on the poly(glycidyl methacrylate‐heptakis(6‐amino‐6‐deoxy)‐β‐cyclodextrin‐co‐ethylene dimethacrylate) monolith, the effect of the ratio of glycidyl methacrylate/heptakis(6‐amino‐6‐deoxy)‐β‐cyclodextrin was especially studied, and satisfactory reproducibility could still be achieved by strictly controlling the composition of the polymerization mixture. To investigate the effect of the degree of amino substitution of β‐cyclodextrin on column performance, a detailed comparison of the two monoliths was also carried out using series of analytes including small peptides and chiral acids. It was found that the β‐cyclodextrin‐functionalized monolith with mono‐glycidyl methacrylate linking spacers demonstrated better chiral separation performance than that with multi‐glycidyl methacrylate linking spacers.     

Synthesis and characterization of spherical and hemispherical polyepoxide micrometer‐sized particles of narrow size distribution by a single‐step swelling of uniform polystyrene template microspheres with glycidyl methacrylate

Polystyrene template microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2‐methoxy ethanol. Spherical and hemispherical polystyrene/poly(glycidyl methacrylate) microspheres of narrow size distribution were prepared by a single‐step swelling of the polystyrene template microspheres with the swelling solvent monomer glycidyl methacylate, followed by polymerization of the monomer within the swollen template microspheres at 73 °C. Uniform polystyrene/poly(glycidyl methacylate‐ethylene glycol dimethacrylate) polyepoxide composite microspheres were synthesized similarly, substituting glycidyl methacylate for glycidyl methacylate and ethylene glycol dimethacrylate. Uniform crosslinked poly(glycidyl methacylate‐ethylene glycol dimethacrylate) polyepoxide microspheres have been prepared by dissolution of the PS template polymer of the former composite microspheres. Particles with different properties, for example size, size distribution, shape, surface morphology, surface area, and so forth, were prepared by changing various parameters belonging to the swelling and/or polymerization steps, for example, volume of the swelling monomer/s and/or the swelling solvent dibutyl phthalate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4612–4622, 2007     

Poly(glycidyl methacrylate‐co‐N‐methylolacrylamide‐co‐ethylene dimethacrylate) monolith coupled to high‐performance liquid chromatography for the determination of adenosine phosphates in royal jelly

A polymer monolith microextraction method coupled with high‐performance liquid chromatography was developed for the determination of adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate. The monolithic column was synthesized inside fused‐silica capillaries using thermal initiation free‐radical polymerization with glycidyl methacrylate as the monomer, ethylene dimethacrylate as the cross‐linker, cyclohexanol, and 1‐dodecanol as the porogen. N‐Methylolacrylamide, an important hydrophilic monomer, was incorporated into the polymerization mixture to enhance the hydrophilicity of the poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) column. The obtained poly(glycidyl methacrylate‐co‐N‐methylolacrylamide‐co‐ethylene dimethacrylate) monolith was characterized by scanning electron microscopy, Fourier‐transform infrared spectra, and X‐ray photoelectron spectroscopy. Optimum conditions for the preconcentration and separation of the target adenosines were also investigated. Under the optimum conditions, we obtained acceptable linearities, low limits of detection, and good relative standard deviations. The developed polymer monolith microextraction with high‐performance liquid chromatography method exhibited a good performance with recovery values in the range of 76.9?104.7% when applied to the determination of the adenosines in five royal jelly samples.     

Ensuring repeatability and robustness of poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) HPLC monolithic columns of 3 mm id through covalent bonding to the column wall

Two different methods to reinforce the poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) HPLC monolithic columns of 3 mm id in a glass column reservoir were studied: composite columns with polymeric particles in the monolith and surface treatment of the reservoir wall. Of the two methods used to counter the mechanical instability and formation of flow channels (composite columns and column wall surface treatment), we demonstrated that proper column wall surface treatment was sufficient to solve both problems. Our study also indicated that no surface treatment is efficient, and of the methods studied silanization in acidified ethanol solution and constant renewal of the reaction mixture (dynamic mode) proved to be the most effective. As a result of this study, we have been able to prepare repeatable and durable methacrylate HPLC columns with good efficiencies.     

Poly(alkyl methacrylate) monolithic columns for HPLC

Several monolithic macroporous polymer sorbents (pore size 1–2 µm) based on alkyl methacrylates and ethylene glycol dimethacrylate as a cross-linking agent were prepared by free radical copolymerization in columns 3×150 mm. The influence of compositions of the reaction mixture and porogens and the nature of the alkyl radical in a mixture of monomers on the hydrodynamic and chromatographic characteristics of the monoliths was studied. The monoliths based on n-butyl methacrylate have rigid macroporous morphology and excellent hydrodynamic characteristics (flow rate up to 5 mL min^?1). The efficiency of separation of a mixture of benzene and its derivatives in the version of reversed-phase HPLC was shown to increase with an increase in the fraction of a lauryl methacrylate additive (LMA) in the reaction mixture. The maximum separation efficiency (number of theoretical plates (tp)) was 35 000 tp m^?1 for the monolith based on n-butyl methacrylate with 7% LMA in the reaction mixture.     

Spherical and Worm‐Like Micelles from Fructose‐Functionalized Polyether Block Copolymers

This paper presents the synthesis and characterization of d ‐fructose modified poly(ethylene glycol) (Fru‐PEG) and fructose modified poly(ethylene glycol)‐block‐poly(ethyl hexyl glycidyl ether) (Fru‐PEG‐b‐PEHG) that are both prepared by initiation with isopropyliden protected fructose, followed by deprotection of the sugar. The block copolymers are self‐assembled into micelles, and are subsequently characterized by cryo‐TEM and dynamic light scattering. The fluorescent dye Nile red is encapsulated as a model hydrophobic compound and fluorescent marker to perform initial uptake tests with breast cancer cells. The uptake of sugar and nonsugar decorated micelles is compared.     

Synthesis of lightly crosslinked zwitterionic polymer‐based bioinspired adhesives for intestinal tissue sealing

In this report, we have developed a new bioinspired medical adhesive capable of providing a leak‐proof barrier for application to intestinal anastomoses. The newly synthesized adhesive is a terpolymer possessing three different repeating units: (1) A zwitterionic polymer, poly(sulfobetaine methacrylate) (polySBMA), for increased hydrophilicity and biocompatibility, (2) a 3,4‐dihydroxy‐L‐phenylalanine (DOPA) segment which contains the catechol group, and (3) poly(ethylene glycol) dimethacrylate (PEGDMA) for light crosslinking, which will be used to strengthen the polymer adhesion properties by providing debonding resistance. The chemical structure of the terpolymer, poly(N‐methacryloyl‐3,4‐dihydroxyl‐L‐phenylalanine‐co‐sulfobetaine methacrylate‐co‐poly(ethylene glycol) dimethacrylate) (poly(MDOPA‐co‐SBMA‐co‐PEGDMA)), synthesized following a convenient and reproducible radical polymerization was clearly confirmed by ¹H NMR. The terpolymer adhesive displayed the optimal adhesion properties when containing 1.5–2.5 mol % of crosslinker, PEGDMA, according to the measured maximum adhesion strength and work of adhesion, characterized by lap shear strength tests utilizing porcine skin. The adhesive did not show cytotoxicity when tested with human embryonic kidney (HEK293A) cells. Ex vivo anastomosis experiments using porcine intestine demonstrated that the new poly(MDOPA‐co‐SBMA‐co‐PEGDMA) is a promising biomedical adhesive which successfully prevents leakage from the sutured intestinal tissue. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1564–1573     

Silver‐coated monolithic columns for separation in radiopharmaceutical applications

In this study, we demonstrate the preparation of a macroporous monolithic column containing anchored silver nanoparticles and its use for the elimination of excess radioiodine from the radiolabeled pharmaceutical. The poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) monolith was first functionalized with cystamine and the free thiol groups liberated by reaction with borohydride. In‐house‐prepared silver nanoparticles were then attached by interaction with the surface thiols. The deiodization process was demonstrated with the commonly used radiopharmaceutical m‐iodobenzylguanidine labeled with radionuclide iodine‐125.     

Polymer monolithic capillary column fabricated by using monodisperse iron oxide nanocrystal template to enhance the electrochromatographic separation of small molecules

Monodisperse iron oxide nanocrystals and organic solvents were utilized as coporogens in monolithic poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) capillary columns to afford stationary phases with enhanced electrochromatographic performance of small molecules. While the conventional monoliths using organic solvents only as a porogen exhibited poor resolution (Rs) <1.0 and low efficiency of 40 000–60 000 plates/m, addition of a small amount of nanocrystals to the polymerization mixture provided increased resolution (Rs > 3.0) and high efficiency ranged from 60 000 to 100 000 plates/m at the same linear velocity of 0.856 mm/s. It was considered that the mesopores introduced by the nanocrystals played an important role in the improvement of the monolith performance. This new strategy expanded the application range of the hydrophobic monoliths in the separation of polar alkaloids and narcotics. The successful applications demonstrated that the glycidyl methacrylate based monoliths prepared by using nanocrystal template are a good alternative for enhanced separation efficiency of small molecules.     

Imidazolium‐based poly(ionic liquid)s with poly(ethylene oxide) main chains: Effects of spacer and tail structures on ionic conductivity

Ten types of cationic glycidyl triazole polymers (GTPs) are prepared from combinations of five alkyl‐imidazolium units (methyl‐, ethyl‐, n‐propyl‐, iso‐propyl‐, and n‐butyl‐imidazoliums) and two spacers [di‐ and tri(ethylene glycol)s]. Since these poly(ionic liquid)s are prepared from the same sample of glycidyl azide polymer by postfunctionalization method, they have the same degree of polymerization. Therefore, the structure–property relationship can be discussed without influence of molecular weight difference. The samples are characterized by NMR, differential scanning calorimetry, and thermogravimetric analysis. The ionic conductivity data are obtained by impedance measurements. The GTPs with the tri(ethylene glycol) spacer and ethyl‐ and n‐butyl‐imidazolium units afford the highest anhydrous conductivity of 1.5 × 10^?5 S cm^?1 at 30 °C. Based on electrode polarization (EP) analysis, we calculate the conducting ion (carrier) concentration and mobility. We discuss the effect of the spacer and N‐alkyl tail structures on the ionic conductivity using the data obtained by EP analysis and X‐ray diffraction. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2896–2906     

Boronate Affinity Monolith with a Gold Nanoparticle‐Modified Hydrophilic Polymer as a Matrix for the Highly Specific Capture of Glycoproteins

As low abundance is the great obstacle for glycoprotein analysis, the development of materials with high efficiency and selectivity for glycoprotein enrichment is a prerequisite in glycoproteome research. Herein, we report a new kind of hydrophilic boronate affinity monolith by attaching 4‐mercaptophenylboronic acid (MPBA) with 2‐mercaptoethylamine (MPA) on the gold nanoparticle‐modified poly(glycidyl methacrylate‐co‐poly(ethylene glycol) diacrylate)) monolith for glycoprotein enrichment. With poly(ethylene glycol) diacrylate as the cross‐linker and the further modification of gold nanoparticles, the matrix has advantages of good hydrophilicity and enhanced surface area, which are beneficial to improve the enrichment selectivity and efficiency for glycoproteins. The attachment of MPBA and MPA provide intramolecular B?N coordination, which could further enhance the specificity of glycoprotein capture. Such a boronate affinity monolith was applied to enrich horseradish peroxidase (HRP) from the mixture of HRP and bovine serum albumin (BSA), and high selectivity was obtained even at a mass ratio of 1:1000. In addition, the binding capacity of ovalbumin on such monolith reached 390 μg g^?1. Furthermore, the average recovery of HRP on the prepared affinity monoliths was (84.8±1.9) %, obtained in three times enrichment with the same column. Finally, the boronate affinity monolith was successfully applied for the human‐plasma glycoproteome analysis. As a result, 160 glycoproteins were credibly identified from 9 μg of human plasma, demonstrating the great potential of such a monolith for large‐scale glycoproteome research.     

A facile and efficient one‐step strategy for the preparation of β‐cyclodextrin monoliths

A novel, facile, and efficient one‐step copolymerization strategy was developed for the preparation of β‐cyclodextrin (β‐CD) methacrylate monolithic columns using click chemistry. The novel mono‐(1H‐1,2,3‐triazol‐4‐ylmethyl)‐2‐methylacryl‐β‐CD monomer was synthesized by a click reaction between propargyl methacrylate and mono‐6‐azido‐β‐CD, and then monolithic columns were prepared through a one‐step in situ copolymerization of the mono‐(1H‐1,2,3‐triazol‐4‐ylmethyl)‐2‐methylacryl‐β‐CD monomer and ethylene dimethacrylate. The physicochemical properties and column performance of the fabricated monolithic columns were characterized by elemental analysis, SEM, and micro‐HPLC. Satisfactory column permeability, efficiency, and separation performance were obtained for the optimized poly(mono‐(1H‐1,2,3‐triazol‐4‐ylmethyl)‐2‐methylacryl‐β‐CD‐co‐ethylene dimethacrylate) monolithic columns. Additionally, typical hydrophilic interaction chromatography retention behavior was observed on the monoliths at high acetonitrile content in the mobile phase. Although the enantioselectivity of our monolithic columns did not meet the level of other reported β‐CD monolithic columns, this one‐step strategy based on click chemistry still provides an interesting and effective model as it offers the possibility to easily prepare related novel CD methacrylate monoliths through a one‐step copolymerization strategy.     

Ion‐exchanger synthesis using reversible addition‐fragmentation chain transfer polymerization

An ion‐exchanger with polyanionic molecular brushes was synthesized by a “grafting from” route based on “surface‐controlled reversible addition‐fragmentation chain transfer polymerization” (RAFT). The RAFT agent, PhC(S)SMgBr was covalently attached to monodisperse‐porous poly(dihydroxypropyl methacrylate‐co‐ethylene dimethacrylate), poly(DHPM‐co‐EDM) particles 5.8 μm in size. The monomer, 3‐sulfopropyl methacrylate (SPM), was grafted from the surface of poly(DHPM‐co‐EDM) particles with an immobilized chain transfer agent by the proposed RAFT protocol. The degree of polymerization of SPM (i. e. the molecular length of the polyanionic ligand) on the particles was controlled by varying the molar ratio of monomer/RAFT agent. The particles carrying polyanionic molecular brushes with different lengths were tested as packing material in the separation of proteins by ion exchange chromatography. The columns packed with the particles carrying relatively longer polyanionic ligands exhibited higher separation efficiency in the separation of four proteins. Plate heights between 130–200 μm were obtained. The ion‐exchanger having poly‐(SPM) ligand with lower degree of polymerization provided better peak‐resolutions on applying a salt gradient with higher slope. The molecular length and the ion‐exchanger group content of polyionic ligand were adjusted by controlling the degree of polymerization and the grafting density, respectively. This property allowed control of the separation performance of the ion‐exchanger packing.     

Hydroxyl Functionalized Uniform‐Porous Beads,Synthesis and Chromatographic Use

Uniform‐porous poly(dihydroxypropyl methacrylate‐co‐ethylene dimethacrylate), poly(DHPM‐co‐EDM) particles were synthesized as an alternative packing material for reversed phase chromatography. In the synthesis, poly(glycidyl methacrylate‐ethylene dimethacrylate), poly(GMA‐co‐EDM) particles were obtained by a multi‐stage swelling and polymerization protocol, the so called “modified seeded polymerization”. For this purpose, 2.4 µm polystyrene seed particles were first swollen by dibutyl phthalate (DBP) and then by a monomer mixture including glycidyl methacrylate and ethylene dimethacrylate. The repolymerization of monomer phase in the swollen seed particles provided porous uniform particles approximately 7 µm in size. Poly(DHPM‐co‐EDM) particles were obtained by the acid hydrolysis of the particles synthesized with different GMA feed concentrations. These particles were used as column‐packing material in the reversed phase separation of alkylbenzenes. The retention factor‐acetonitrile concentration diagrams clearly showed that the polarity of packing material could be controlled by changing the GMA feed concentration in the “modified seeded polymerization”. The packing materials with more hydrophobic character (i.e., poly(EDM) and poly(DHPM‐co‐EDM) particles produced with the GMA feed concentrations up to 20%) exhibited better chromatographic performance in the reversed phase mode.     

Synthesis of inositol‐based star polymers through low ppm ATRP methods

The vitamin B₈‐based macroinitiator with six 2‐bromoisobutyric initiating sites was prepared for the first time by the transesterification reaction of meso‐inositol with 2‐bromoisobutyryl bromide. A series of six‐armed (co)polymers, containing hydrophilic poly(di(ethylene glycol) methyl ether methacrylate) and amphiphilic poly(di(ethylene glycol) methyl ether methacrylate)‐block‐poly(methyl methacrylate) as the arms and meso‐inositol as the core, were obtained by low ppm atom transfer radical polymerization (ATRP) methods, utilizing 30 ppm of catalyst complex. Under Fe⁰‐mediated supplemental activators and reducing agents ATRP, Cu⁰‐mediated supplemental activators and reducing agents ATRP, Ag⁰‐mediated activators regenerated by electron transfer ATRP, and simplified electrochemically mediated ATRP conditions, polymerization proceeded on to high conversion while maintaining low dispersity (?  = 1.05–1.16) giving well‐defined six‐armed star (co)polymers. ¹H NMR spectral results confirm the formation of new star‐shaped block (co)polymers. The absence of intermolecular coupling reactions during synthesis was confirmed by gel permeation chromatography analyses of the side chains of received star (co)polymers. These vitamin B₈‐based star (co)polymers may find biomedical applications as thermo‐sensitive drug delivery systems, biosensors, and tissue engineering solutions. Copyright © 2017 John Wiley & Sons, Ltd.     

Determination of betaine,l‐carnitine,and choline in human urine using a self‐packed column and column‐switching ion chromatography with nonsuppressed conductivity detection

A simple method for the determination of betaine, l ‐carnitine, and choline in human urine was developed based on column‐switching ion chromatography coupled with nonsuppressed conductivity detection by using a self‐packed column. A pretreatment column (50 mm × 4.6 mm, id) packed with poly(glycidyl methacrylate‐divinylbenzene) microspheres was used for the extraction and cleanup of analytes. Chromatographic separation was achieved within 10 min on a cationic exchange column (150 mm × 4.6 mm, id) using maleic anhydride modified poly(glycidyl methacrylate‐divinylbenzene) as the particles for packing. The detection was performed by ion chromatography with nonsuppressed conductivity detection. Parameters including column‐switching time, eluent type, flow rates of eluent, and interfering effects were optimized. Linearity (r ² ≥ 0.99) was obtained for the concentration range of 0.50–100, 0.75–100, and 0.25–100 μg/mL for betaine, l ‐carnitine, and choline, respectively. Detection limits were 0.12, 0.20, and 0.05 μg/mL for betaine, l ‐carnitine, and choline, respectively. The intra‐ and interday accuracy and precision for all quality controls were within ±10.11%. Satisfactory recovery was observed between 92.5 and 105.0%. The validated method was successfully applied for the determination of betaine, l ‐carnitine, and choline in urine samples from healthy people.     

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     

PEG‐Modified Macroporous Poly(Glycidyl Methacrylate) and Poly(2‐Hydroxyethyl Methacrylate) Microspheres to Reduce Non‐Specific Protein Adsorption

To minimize non‐specific protein adsorption on macroporous poly(glycidyl methacrylate) and poly(2‐hydroxyethyl methacrylate) microspheres containing amino and/or carboxyl groups, the microspheres are coated with α,ω‐bis‐carboxy poly(ethylene glycol) and amino‐terminated poly(ethylene glycol‐co‐propylene glycol) or α‐methoxy‐ω‐amino poly(ethylene glycol). Adsorption of bovine serum albumin (BSA), γ‐globulin, ¹²⁵I‐BSA, pepsin, and chymotrypsin on neat and PEGylated microspheres is determined by UV–VIS spectroscopy of supernatants and eluates or by measurement of radioactivity in an ionization chamber. Neat and PEGylated microspheres adsorb 0.8–70% and 0.02–44% of protein, respectively.