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Gelation in the presence of cells with minimum cytotoxicity is highly desirable for materials with applications in tissue engineering. Herein, the naturally occurring polysaccharide pullulan is functionalized with thiolactones that undergo ring-opening addition of amines. As a result, the modified pullulan can be cross-linked with diamines and/or amine-containing biological substrates enhancing the system's versatility (e.g., gelatin and cell-binding ligands GHK/GRGDS). Thiolactone degrees of substitution of 2.5 or 5.0 mol % are achieved, and respective hydrogels exhibit mesh sizes of 27.8 to 49.1 nm. Cell proliferation studies on chosen gels (G' ≅ 500 Pa, over 14 days) demonstrate that for normal human dermal fibroblasts (NHDFs), both gelatin and GRGDS equally support cell proliferation, while in the case of hepatocytes (HepG2), the presence of GRGDS and GHK improve cell proliferation 10-fold compared to gelatin. Cells remain viable and in one instance were successfully encapsulated by in situ gelation, altogether confirming the mild and biocompatible nature of this strategy to produce biogels using biologically active substrates as cross-linkers.

In this work we successfully synthesized degradable microgels based on poly(N-vinylcaprolactam) (PVCL) with hydrophobic pockets for the uptake/release of poorly water-soluble molecules. The degradability as well as the presence of hydrophobic pockets in the microgel structure are ensured by incorporation of a star-shaped acrylate-functionalised poly(e-caprolactone) (starPCL) crosslinkers. Microgels with variable amount of star PCL crosslinker, narrow size distribution and a hydrodynamic radius of 200–400 nm were obtained by miniemulsion polymerisation. The microgel size and size distribution was characterised by means of dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM) and sedimentation analysis. The obtained microgels undergo enzymatic degradation in aqueous medium as evidenced by DLS, nuclear magnetic resonance (NMR) and FESEM. Additionally, the uptake of hydrophobic molecules like the dye Nile-Red (model system) and the drug Ibuprofen into the starPCL-based microgels was proven by ultraviolet–visible spectroscopy (UV/Vis). The experimental data indicate that the solubilisation ability of microgels can be regulated by the amount of crosslinker in the microgel structure.

Reactive surfactants (surfmers), which are covalently attached to the surface of sub-micron sized polymer particles during emulsion polymerisation, are applied to tailor the surface functionality of polymer particles for an application of choice. We present a systematic study on the use of oligoglycidol-functionalised styrene macromolecules as surfmers in the emulsion polymerization of styrene. Firstly, we report the impact of the surfmer concentration on the particle size for polymerisations performed above and below the critical micelle concentration. Secondly, we report the influence of the oligoglycidol chain length on the particle size. Thirdly, we conducted experiments to analyse the influence of the surfmer concentration and its chain length on the colloidal stability of the aqueous polystyrene nanoparticles in sodium chloride solutions. We demonstrated that the size of polystyrene particles could be influenced by changing both the surfmer concentration and its chain length. Furthermore, we showed that the colloidal stability of the oligoglycidol-functionalized polystyrene particles is dependent on the particle size, and not directly related to the oligoglycidol chain length. The research work in this paper was carried out within Brightlands Materials Center, a joint research initiative between TNO and the province of Limburg. The work is funded by the Dutch government as well as the province of Limburg. Additionally, the work was partly performed within the Interreg Vlaanderen-Nederland project EnEf and within the Sia RAAK Pro project Window of the Future. Buskens, P (corresponding author), Zuyd Univ Appl Sci, Nieuw Eyckholt 300, NL-6400 AN Heerlen, Netherlands; Hasselt Univ, Inst Mat Res Inorgan & Phys Chem, Agoralaan Bldg D, B-3590 Diepenbeek, Belgium. Mann, D; Buskens, P (corresponding author), Netherlands Org Appl Sci Res TNO, High Tech Campus 25, NL-5656 AE Eindhoven, Netherlands; Brightlands Mat Ctr, Urmonderbaan 22, NL-6167 RD Geleen, Netherlands. 1522736waulthers@zuyd.nl; ryan.vanzandvoort@tno.nl; 1658905castermans@zuyd.nl; jeroen.welzen@chillabs.nl; evelien.baeten@zuyd.nl; kathleen.stout@zuyd.nl; keul@rwth-aachen.de; daniel.mann@tno.nl; pascal.buskens@tno.nl

In this work we focused on synthesis and characterization of aqueous poly(N-vinylcaprolactam) (PVCL) microgels decorated with oligoglycidol-macromonomers. Oligoglycidol macromonomers with styrene or acrylate polymerisable group and tunable length of the oligoglycidol chain (6, 12 and 50 glycidol units) were synthesized. The microgels were synthesized by aqueous precipitation copolymerization of N-vinylcaprolactam and oligoglycidol macromonomers in presence of crosslinking agent. The length of the oligoglycidol chain and the concentration of macromonomer in the reaction mixture were varied to investigate a direct influence on the polymerization rate and microgel properties. Synthesized microgels exhibit radii from 50 to 350 nm and show temperature-responsive properties. We demonstrate that oligoglycidol macromonomers are localized predominantly on the microgel surface. This ensures excellent colloidal stabilisation of oligoglycidol-decorated microgels in aqueous solutions and functionalization of microgels with hydroxyl groups, which can be potentially used for further post-modification reactions.

The photoinduced radical generation process has received renewed interest due to its economic and ecological appeal. Herein the light-induced cross-linking of functional polyglycidol and its post-cross-linking modification are presented. Linear polyglycidol was first functionalized with a tertiary amine in a two-step reaction. Dimethylaminopropyl functional polyglycidol was cross-linked in a UV-light mediated reaction with camphorquinone as a type II photoinitiator. The cross-linked polyglycidol was further functionalized by quaternization with various organoiodine compounds. Aqueous dispersions of the cross-linked polymers were investigated by means of DLS and zeta potential measurements. Polymer films were evaluated by DSC and XPS.

For the preparation of electrically conductive composites, various combinations of cellulose and conducting materials such as polymers, metals, metal oxides and carbon have been reported. The conductivity of these cellulose composites reported to date ranges from 10−6 to 103 S cm−1. Cellulose nanocrystals (CNCs) are excellent building blocks for the production of high added value coatings. The essential process steps for preparing such coatings, i.e. surface modification of CNCs dispersed in water and/or alcohol followed by application of the dispersion to substrate samples using dip coating, are low cost and easily scalable. Here, we present coatings consisting of Ag modified CNCs that form a percolated network upon solvent evaporation. After photonic sintering, the resulting coatings are electrically conductive with an unprecedented high conductivity of 2.9 × 104 S cm−1. Furthermore, we report the first colloidal synthesis that yields CNCs with a high degree of Ag coverage on the surface, which is a prerequisite for obtaining coatings with high electrical conductivity.

Protecting groups are commonly applied in multi-step molecular syntheses to protect one or multiple functional groups from reacting. After the reaction, they are removed from the molecule. In full analogy to this concept, we report the practical and scalable colloidal synthesis of Au semishells using polyphenylsiloxane protecting patches to prevent part of the surface of polystyrene nanoparticles from being covered with Au. After Au deposition, the patches are removed yielding Au semishells. We anticipate that this strategy can be extended to the synthesis of other types of non-centrosymmetric nanoparticles.

Journal of applied polymer science 12, (2019). doi:10.1002/app.48371, Published by Wiley, New York, NY [u.a.]

Full control over the ceiling temperature (Tc) enables a selective transition between the monomeric and polymeric state. This is exemplified by the conversion of the monomer 2-allyloxymethyl-2-ethyl-trimethylene carbonate (AOMEC) to poly(AOMEC) and back to AOMEC within 10 h by controlling the reaction from conditions that favor ring-opening polymerization (Tc > T0) (where T0 is the reaction temperature) to conditions that favor ring-closing depolymerization (Tc < T0). The ring-closing depolymerization (RCDP) mirrors the polymerization behavior with a clear relation between the monomer concentration and the molecular weight of the polymer, indicating that RCDP occurs at the chain end. The Tc of the polymerization system is highly dependent on the nature of the solvent, for example, in toluene, the Tc of AOMEC is 234 °C and in acetonitrile Tc = 142 °C at the same initial monomer concentration of 2 M. The control over the monomer to polymer equilibrium sets new standards for the selective degradation of poly...

Plasmonics 12(3), 929-945 (2016). doi:10.1007/s11468-016-0345-8, Published by Springer, New York, NY [u.a.]

The synthesis of an epoxy thiolactone is described. The reactivity of this epoxy thiolactone towards amines is evaluated and presented in a four component reaction. Upon ring opening of the thiolactone with an amine an AB-type epoxy thiol monomer is generated which in situ starts a thiol–epoxy polymerization. The polymerization mechanism and kinetics are investigated: the influence of different parameters such as solvent, substrate concentration, and catalyst on the reaction course is explored. Finally, concepts for the formation of reactive hydrogels are presented.

Anionic ring opening copolymerization of ethylene carbonate (EC) and tert-butyl glycidyl ether (TBGE) with CsOH as an initiator using a mono-mode microwave reactor results in poly(EO-co-TBGE) hydroxy telechelic copolymers with Mn(SEC) values between 750 and 1700 g mol−1 and dispersity indices in the range of Đ = 1.05–1.10. The reaction sequence for the formation of narrowly distributed copolymers was investigated by kinetic studies using size exclusion chromatography, 1H NMR and MALDI-ToF as analytical tools. Transcarbonylation, transalkylation and carbonate fragmentation were identified as fundamental reactions for the formation of carbonate free products with multi block microstructures. 13C NMR analysis allowed the determination of monomer sequences within the polymer chain, which confirmed its multi block type structure; different microstructures were obtained by varying the reaction time and monomer composition.

Polymer chemistry / Royal Society of Chemistry 7(2), 364-369(2016). doi:10.1039/C5PY01566A, Published by RSC Publ., Cambridge

Synthetic amphiphilic copolymers with strong antimicrobial properties mimicking natural antimicrobial peptides were obtained via synthesis of an alternating copolymer of maleic anhydride and 4-methyl-1-pentene. The obtained copolymer was modified by grafting with 3-(dimethylamino)-1-propylamine (DMAPA) and imidized in a one-pot synthesis. The obtained copolymer was modified further to yield polycationic copolymers by means of quaternization with methyl iodide and dodecyl iodide, as well as by being sequentially quaternized with both of them. The antimicrobial properties of obtained copolymers were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus. Both tested quaternized copolymers were more active against the Gram-negative E. coli than against the Gram-positive S. aureus. The copolymer modified with both iodides was best when tested against E. coli and, comparing all three copolymers, also exhibited the best effect against S. aureus. Moreover, it shows (limited) selectivity to differentiate between mammalian cells and bacterial cell walls. Comparing the minimum inhibitory concentration (MIC) of Nisin against the Gram-positive bacteria on the molar basis instead on the weight basis, the difference between the effect of Nisin and the copolymer is significantly lower.

Antimicrobial polymers are an attractive alternative to low molecular weight biocides, because they are non-volatile, chemically stable, and can be used as non-releasing additives. Polymers with pendant quaternary ammonium groups and hydrophobic chains exhibit antimicrobial properties due to the electrostatic interaction between polymer and cell wall, and the membrane disruptive capabilities of the hydrophobic moiety. Herein, the synthesis of cationic–hydrophobic polyglycidols with varying structures by post-polymerization modification is presented. The antimicrobial properties of the prepared polyglycidols against E. coli and S. aureus are examined. Polyglycidol with statistically distributed cationic and hydrophobic groups (cationic–hydrophobic balance of 1:1) is compared to (i) polyglycidol with a hydrophilic modification at the cationic functionality; (ii) polyglycidol with both—cationic and hydrophobic groups—at every repeating unit; and (iii) polyglycidol with a cationic–hydrophobic balance of 1:2. A relationship between structure and properties is presented.

Polymers 10(5), 524 (2018). doi:10.18154/RWTH-2018-225705, Published by MDPI, Basel

Antimicrobial polymers are an attractive alternative to low molecular weight biocides, because they are non-volatile, chemically stable, and can be used as non-releasing additives. Polymers with pendant quaternary ammonium groups and hydrophobic chains exhibit antimicrobial properties due to the electrostatic interaction between polymer and cell wall, and the membrane disruptive capabilities of the hydrophobic moiety. Herein, the synthesis of cationic–hydrophobic polyglycidols with varying structures by post-polymerization modification is presented. The antimicrobial properties of the prepared polyglycidols against E. coli and S. aureus are examined. Polyglycidol with statistically distributed cationic and hydrophobic groups (cationic–hydrophobic balance of 1:1) is compared to (i) polyglycidol with a hydrophilic modification at the cationic functionality; (ii) polyglycidol with both—cationic and hydrophobic groups—at every repeating unit; and (iii) polyglycidol with a cationic–hydrophobic balance of 1:2. A relationship between structure and properties is presented.

The functionalization of polymers with phosphorus based reagents is of great interest in the preparation of polymeric materials. In this work we present a straightforward method for the introduction of pendant diethyl phosphate groups into polyglycidol by reaction with diethyl chlorophosphate. The degree of functionalization was controlled by the ratio of the phosphorus reagent to the hydroxyl groups attached to the polyether backbone. Resulting polymers were characterized by 1H, 13C, 31P {1H} NMR spectroscopy, FTIR spectroscopy and SEC analysis. The removal of one and both ethyl groups of the phosphate ester was selectively achieved by reaction with sodium iodide or bromotrimethylsilane, respectively.

The employment of a monomer-specific “on/off switch” was used to synthesize a nine-block copolymer with a predetermined molecular weight and narrow distribution (Đ = 1.26) in only 2.5 h. The monomers consisted of a six-membered cyclic carbonate (i.e., 2-allyloxymethyl-2-ethyl-trimethylene carbonate (AOMEC)) and ε-caprolactone (εCL), which were catalyzed by 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD). The dependence of polymerization rate with temperature was different for the two monomers. Under similar reaction conditions, the ratio of the apparent rate constant of AOMEC and εCL [kpapp(AOMEC)/kpapp(εCL)] changes from 400 at T = −40 °C to 50 at T = 30 °C and 10 at T = 100 °C. Therefore, by decreasing the copolymerization temperature from 30 °C to −40 °C, the conversion of εCL can be switched “off”, and by increasing the temperature to 30 °C, the conversion of εCL can be switched “on” again. The addition of AOMEC at T = −40 °C results in the formation of a pure carbonate block. The cyclic addition of AOMEC to a solution of εCL along with a simultaneous temperature change leads to the formation of multiblock copolymers. This result provides a new straightforward synthetic route to degradable multiblock copolymers, yielding new interesting materials with endless structural possibilities.

The compartmentalization of microgels is a challenging task for synthetic polymer chemistry. Although the complexation with low molecular weight compounds or the use of microfluidic techniques offer attractive possibilities for other length scales, it is difficult to implement compartments in the mesoscale range of 10-100 nm. Herein we show how simple blending of reactive prepolymers is suitable to design new microgel morphologies with tailored compartments. We use poly(EEGE)-block-poly(AGE) as crosslinkable, pro-hydrophilic prepolymer in blends with varying amounts of crosslinkable, yet hydrophobic poly(THF-stat-AllylEHO) or inert and hydrophobic polystyrene, and crosslink the allyl functional prepolymer(s) in a thiol-ene click-type reaction after miniemulsification. Our strategy shows how arrested versus free nanophase separation can be used to control easily the morphology and polarity of microgel particles.

Hydrophilic adhesion promoters that facilitate intimate binding between metals and polymers are an important class of materials with a wide variety of applications in biomedical coatings. Currently, non-poly(meth-)acrylate based hydrophilic polymeric adhesives are unavailable. Here, we report the preparation of such adhesion-promoters based on linear polyglycidol for biomedical applications. The adhesion promoting polymer is prepared from partly phosphonoethylated polyglycidol in three steps. First, the remaining hydroxyl groups of the polyglycidol backbone are reacted with acryloyl chloride; secondly, the phosphonate groups are chemoselectively dealkylated using bromotrimethylsilane. Finally, the bis(trimethylsilyl)phosphonate intermediate is converted to the phosphonic acid through ethanolysis. The reaction conditions of each synthetic step are optimized individually and the products are characterized by 1H, 31P NMR and SEC analysis. The optimized reaction conditions are applied to establish a straightforward one-pot reaction, resulting in an ethanolic formulation of the adhesion promoter, which can be used immediately for the coating application. Special attention is paid to the stability of the intermediates, the chemoselectivity of the reactions and the shelf-life of the product. 1H NMR spectroscopy reveals hydrolytic instability of the product under ambient conditions; however, the polymers are sufficiently stable in dry ethanol for at least 14 days. The combination of this hydrophilic polymer with acrylate and phosphonic acid groups constitutes a versatile platform technology for the preparation of thin primer coatings on metal substrates for biomedical applications. The phosphonic acid residues assure strong binding to stainless steel wires and the acrylates can be addressed by UV light to enable crosslinking, thus improving mechanical stability and adhesion between the substrate and a biomedical hydrogel coating. The quality of the adhesion promotion to stainless steel wires is verified by using a lubricious, hydrogel top coat and by evaluating friction and wear resistance of this total coating system. Constant values for friction and wear are obtained, proving the applicability of phosphonic acid-functionalized polyglycidols as metal adhesion promoters for biomedical applications.

Polymers 10(1), 37 (2018). doi:10.18154/RWTH-2018-223455 special issue: "Special Issue "Fluorinated Polymers" / Guest Editor: Prof. Dr. Hideo Sawada, Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki, University, Hirosaki, Japan", Published by MDPI, Basel

Terpolymers of homogeneous composition were prepared by free radical copolymerization of butyl or dodecyl methacrylate, 1H,1H,2H,2H-perfluorodecyl methacrylate and maleic anhydride using the continuous monomer addition technique. The copolymerization reactions were performed at 65 °C in the presence of azobisisobutyronitrile as an initiator in a mixture of methyl ethyl ketone and 1,3-bis (trifluoromethyl)benzene. The monomers and initiator are added to the reaction mixture with the same rate they are consumed in 5- and 10-fold excess compared to the initial monomer stock. The obtained terpolymers with molecular weights Mn = 50,000–70,000 are of uniform composition, close to the composition determined in low conversion experiments, proving the principle of the chosen concept. The kinetic data necessary for the design of the continuous addition experiment were obtained from binary copolymerization experiments at low monomer conversion (to avoid compositional drift). In addition, the so-called terpolymerization parameter was determined from ternary copolymerization experiments.

Janus particles are of great research interest because of their reduced symmetry, which provides them with unique physical and chemical properties. Such particles can be prepared from spherical structures through colloidal assembly. Whilst colloidal assembly has the potential to be a low cost and scalable process, it typically lacks selectivity. As a consequence, it results in a complex mixture of particles of different architectures, which is tedious to purify. Very recently, we reported the colloidal synthesis of Au semishells, making use of polystyrene–polyphenylsiloxane Janus particles as an intermediate product (Chem. Commun. 2017, 53, 3898–3901). Here, we demonstrate that these Janus particles are realized through colloidal assembly of spherical glucose-functionalized polystyrene particles and an emulsion of phenyltrimethoxysilane in aqueous ammonia, followed by interfacial polycondensation to form the polyphenylsiloxane patch. Both the polystyrene spheres and the emulsion of Ph-TMS in aqueous ammonia are stabilized by a surfmer—a reactive surfactant. The colloidal assembly reported in this manuscript proceeds with an unexpected high selectivity, which makes this process exceptionally interesting for the synthesis of Janus particles. Furthermore, we report insights into the details of the mechanism of formation of these Janus particles, and apply those to adapt the synthesis conditions to produce polystyrene particles selectively decorated with multiple polyphenylsiloxane patches, e.g., raspberry particles.

Quantification of the stimuli-responsive phase transition in polymers is topical and important for the understanding and development of novel stimuli-responsive materials. The temperature-induced phase transition of poly(N-isopropylacrylamide) (PNIPAm) with one thiol end group depends on the confinement—free polymer or polymer brush—on the molecular weight and on the nature of the second end. This paper describes the synthesis of heterotelechelic PNIPAm of different molecular weights with a thiol end group—that specifically binds to gold nanorods and a hydrophilic NIPAm end group by reversible addition-fragmentation chain-transfer polymerization. Proton high-resolution magic angle sample spinning NMR spectra are used as an indicator of the polymer chain conformations. The characteristics of phase transition given by the transition temperature, entropy, and width of transition are obtained by a two-state model. The dependence of thermodynamic parameters on molecular weight is compared for hydrophilic and hydrophobic end functional-free polymers and brushes.

The use of bio-based building blocks for polymer synthesis represents a milestone on the way to “green” materials. In this work, two synthetic strategies for the preparation of multifunctional polymers are presented in which the key element is the functionality of homoserine lactone. First, the synthesis of a bis cyclic coupler based on a thiolactone and homoserine lactone is displayed. This coupler was evaluated regarding its regioselectivity upon reaction with amines and used in the preparation of multifunctional polymeric building blocks by reaction with diamines. Furthermore, a linear polyglycidol was functionalized with homoserine lactone. The resulting polyethers with lactone groups in the side chain were converted to cationic polymers by reaction with 3-(dimethylamino)-1-propylamine followed by quaternization with methyl iodide.

In this manuscript, a biscyclic monomer with an epoxide and a thiolactone ring connected by a urethane bond is used for the synthesis of amino acid-functional polyelectrolytes. In a first step, lithium salts of amino acids react selectively with the thiolactone ring by ring-opening, formation of an amide bond, and a thiol group. In a second step and in the presence of a base a polymeric building block is formed by polyaddition of the thiolate to the epoxide ring. The reaction occurs at room temperature in water as solvent. The resulting polymeric building block has a poly(thioether urethane) backbone, with hydroxyl- and amino acid side groups; the connection of the amino acid to the backbone occurs by an amide bond. As proof of concept, a selected series of amino acids and derivatives of such is used: glycine, alanine, tyrosine, glutamic acid, ε-amino caproic acid (as a lysine surrogate), BOC-lysine-O-methyl ester, BOC-lysine, and the dipeptide carnosine. The resulting polymer building blocks with molecular weights of M

A simple, robust one pot procedure for the preparation of waterborne multifunctional poly(vinyl amine)s (PVAms) is presented. By post-polymerization modification of PVAm with a bifunctional coupler and functional couplers cationic, reactive azetidinium groups, and alkyl chains are introduced in the side chains of PVAms. The structure-activity relations (effect of hydrophobic and cationic modifications) of these antimicrobial polymers are studied; the minimum inhibitory concentration (MIC) against both (Gram positive and Gram negative bacteria) of the library of multifunctional poly(vinyl amine)s are determined to identify the candidates with the highest efficacy. Furthermore, the hemolytic activity-the effective concentration at which 50 and 10% of red blood cells are killed (HC50 and HC10 )-of selected polymers is determined. The ability of the polymers prepared to differentiate between microorganisms (Gram positive and Gram negative bacteria) and mammalian cells (red blood cells) is understood by comparing MIC and HC values. Finally, as an example, the best polymer is used to prepare an antimicrobial surface.

The use of prepolymers for microgel synthesis via miniemulsification allows predefining the chemical functionality and the nanostructure of microgels. We report on tailor-made polyglycidol-based prepolymers using three protected glycidol monomers (allyl glycidyl ether, AGE; ethoxy ethyl glycidyl ether, EEGE; and tert-butyl glycidyl ether, tBGE). AGE with its pendant double bonds serves as site for cross-linking or functionalization, whereas the EEGE and tBGE building blocks represent precursors for hydroxyl functionalities. Following the prepolymer approach, we design statistical and block copolymers to control the nanostructure of the microgel. Cross-linking of the prepolymers is achieved in miniemulsions under UV irradiation in a thiol–ene click type reaction addressing the allyl groups with 2,2′-(ethylenedioxy)diethanethiol. Analysis with cryo-TEM reveals that microgels derived from poly(glycidol)-block-poly(AGE) show larger hydrophobic domains than microgels derived from statistical copolymers. Additi...

Functionalized polyethylenimine–dye (FPEI) is prepared by mixing branched polyethyleneimine (PEI), in which its primary amine groups are modified at different ratios with a quaternary ammonium coupler (QI), and reactive dyestuff (RD) (QI/RD = 0/100, 20/80, 40/60, 60/40 and 80/20 mole/mole %). The deposition of FPEI from an aqueous solution onto the surface of cotton and wool fibres is studied. The adsorption of a charged polymer from an aqueous medium by cotton and wool fibres is investigated at different pH values, and the uptake of colour on fibres is measured by Datacolor and UVVIS spectrophotometers. The study of the kinetics of adsorption shows that pseudo-first-order kinetics provide the best correlation of the experimental data. The equilibrium data indicate that the deposition process onto both cotton and wool follows the Langmuir isotherm. In terms of colour strength (K/S value) the coated fibres compare well with those dyed with a commercial dyestuff, C.I. Basic Red 51, which suggests that the coating is a good alternative to classical dyeing.

A highly stable benzimidazolylidene based N-heterocyclic carbene (NHC) ruthenium catalyst was prepared starting with readily accessible starting materials. Under inert gas atmosphere and in air the catalyst showed high activity for the direct synthesis of esters from primary alcohols and of amides from primary alcohols and amines. Di-, tri-, and oligo-amides were obtained by using specific starting materials.

The preparation of multifunctional polymers and block copolymers by a straightforward one-pot reaction process that combines enzymatic transacylation with light-controlled polymerization is described. Functional methacrylate monomers are synthesized by enzymatic transacylation and used in situ for light-controlled polymerization, leading to multifunctional methacrylate-based polymers with well-defined microstructure.

A novel amphiphilic graft copolymer composed of poly(γ-glutamic acid) (γ-PGA) as a hydrophilic backbone and dodecylamine (DOA) as a hydrophobic side chain (γ-PGA-DOA) was successfully synthesized by employing 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) as the coupling reagent. The grafting degree was stoichiometrically controlled by adjusting the feeding amounts of DOA and EDC in the reaction system. γ-PGA-DOA, with a grafting degree of 55%, self-assembled via hydrophobic interactions and formed microparticles (MPs; diameter of 13±3 μm) in an aqueous solution. These MPs possessed functional carboxylic groups and could be further modified with compounds such as drugs, proteins and peptides, and thus have great potential as vaccine carriers. We report the preparation of novel functional microparticles by self-assembly of amphiphilic copolymer composed of poly(γ-glutamic acid) (γ-PGA) as a hydrophilic backbone and dodecylamine (DOA) as a hydrophobic side chain (γ-PGA-DOA). γ-PGA-DOA with a grafting degree of 55% self-assembled by hydrophobic interaction, and formed microparticles (diameter 13±3 μm) in aqueous solution. These microparticles possess functional carboxylic groups, and could be further modified with active compounds such as drugs, proteins and peptides, and thus have great potential as vaccine carriers.

The synthetic route for the preparation of α,ω-isocyanate-telechelic poly(methyl methacrylate-co-acryloxysuccinimide) and α,ω- isocyanate-telechelic poly(methyl methacrylate-co-acrylamidohexanoic succinimide) soft segments is presented. The strategy includes reversible addition fragmentation chain transfer (RAFT) copolymerization and two post polymerization modification steps. The RAFT polymerizations result in copolymers with an activated ester proportion within the polymer chains of 8% N-acryloxysuccinimide and 5% 6-acrylamidohexanoic succinimide. The reactivity ratios of the monomer pairs were determined. In a first post polymerization reaction carboxylic acid homo telechelic polymers were prepared by reacting the ω-dithiobenzoate end-group with an excess of azobis(cyanovaleric acid). In a second modification step the α- and ω-carboxylic acid end-groups were reacted with hexamethylene diisocyanate and 100% isocyanate telechelic copolymers were obtained. Finally segmented polyurethanes were prepared by coupling hexamethylene diisocyanate (HDI) end capped soft segments with hard segments composed of 1,4-butanediol and HDI. © 2013 Society of Chemical Industry

Polyether graft polyester copolymers with pendant diethylphosphonatoethyl groups (DEPE), P(GDEPE-co-(G-g-eCL)-co-G), were prepared by enzymatic grafting of e-caprolactone from polyglycidols carrying 0, 15.4, and 38.5% of DEPE groups. The graft copolymers were characterized by 1H, 13C, and 31P NMR spectroscopy and SEC analysis. Despite the steric bulk of the DEPE residues, high initiation efficiencies (IE) of the phosphonoethylated macroinitiators could be achieved by appropriate choice of the reaction parameters such as lipase and monomer concentration. Depending on the degree of functionalization of polyglycidol with phosphonate residues (FDEPE), the IE is tunable in a wide range from 31 to 81%. The graft copolymers with pendant phosphonate groups are promising candidates for hydrolytically degradable biomaterials, since all building blocks are biocompatible and/or biodegradable.

International journal of molecular sciences 14(5), 9722-9736 (2013). doi:10.18154/RWTH-CONV-085528, Published by Molecular Diversity Preservation International, Basel

Glycerol and d , l -homocysteine thiolactone – two bio-based building blocks – were used to prepare a bis-cyclic AA′ monomer (or coupler) with an ethylene carbonate and a thiolactone ring linked by an O-methyl urethane spacer. On reaction of this monomer with diamines at 70 °C poly(amide urethane)s with pendant thioethyl and hydroxymethyl side groups are produced in one step. Monodisperse diamines of low molecular weight (MW), monodisperse amino telechelic poly(ethylene oxide) (MW = 897.10) and polydisperse amino telechelic polytetrahydrofuran (Mn = 1100) were used as amine building blocks. By reaction of the coupler with diamines at room temperature only the thiolactone ring is converted. Consequently, a bis(ethylene carbonate) bis(thiol) is obtained if one equivalent diamine is reacted with two equivalents of coupler. Reaction of this intermediate with a second diamine leads to poly(amide urethane)s with pendant thioethyl and hydroxymethyl side groups and alternating amine building blocks. Post-polymerization modification of thiol side groups leads to polymers with designed properties. The microstructure of the obtained polymers was proven by 1H NMR and Raman spectroscopy; the molecular weights were determined by size exclusion chromatography.

Well-defined homopolymers of 2-hydroxyethyl acrylate (HEA) with different degrees of polymerization are synthesized via reversible addition–fragmentation chain transfer polymerization (RAFT), using dibenzyltrithiocarbonate (DBTTC) as chain transfer agent. Subsequently, well-defined triblock copolymers of HEA and 2-methoxyethyl acrylate (MEA) with the general microstructure P(HEA)-block-P(MEA)-block-P(HEA) and P(HEA)-block-P(HEA-grad-MEA)-block-P(HEA) are synthesized via RAFT, using previously prepared HEA-based homopolymers with degrees of polymerization of Pn ∼ 20–70 as macro-chain transfer agents (MCTAs). Kinetic investigations on all of the performed (co)polymerizations are summarized, revealing that all polymerizations proceed in a controlled manner. The thermoresponsive properties of aqueous solutions of the synthesized copolymers with block or gradient microstructures are determined and discussed, revealing adjustable cloud point (CP) temperatures between 0 and 80 °C for copolymers with the pure blo...

A bifunctional coupler bearing an azetidinium and an aminochlorohydrin group was synthesized in water as solvent starting with piperazine and epichlorohydrin. Conversion of the bifunctional coupler...

A new synthetic approach to thiol functional, well-defined amphiphilic block copolymers, which can be used to prepare multifunctional polymers and polymeric nanoparticles, is presented. Starting with a hydrophilic macroRAFT transfer agent and hydrophobic (meth)acrylate monomers that possess protected thiol groups, amphiphilic block copolymers are prepared in high yield. It is proven that the protected thiol groups in the monomer do not interfere with the RAFT polymerization process. Polymers with defined molecular weight, narrow polydispersities (PDI

Linear aliphatic polyesters having pendant hydroxyl groups were successfully synthesised by polycondensation using scandium triflate as catalyst. A first set of samples was prepared starting with hexane-, octane-, decane-, and dodecanediol and l -malic acid as hydroxyl functional dicarboxylic acid, on the one hand, and succinic acid as non-functional analogue, on the other. A second set of samples was prepared starting with different hydroxytelechelic oligo(e-caprolactone)s, synthesised in a ring opening polymerisation (ROP) initiated by hexanediol using the same catalyst, and reacted with l -malic acid or succinic acid, respectively. The successful reaction was confirmed by nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS). The thermal properties of both types of polyesters – with and without pendant hydroxyl groups – were analysed by differential scanning calorimetry (DSC). While all polyesters based on succinic acid are highly crystalline, for the polyesters based on l -malic acid the crystallinity depends on the concentration of pendant hydroxyl groups and on the microstructure. Hence, the influence of the hydroxyl group enables to tailor the crystallinity.

Isocyanate homo telechelic poly(methyl methacrylate-co-allyl methacrylate)s were prepared and used as soft segments for thermoplastic polyurethanes. Copolymerization of allyl methacrylate and methyl methacrylate by RAFT leads to selective conversion of the methacrylate C,C double bonds, leaving the allyl groups in the polymer side chain intact. A hetero telechelic MMA/AMA copolymer (Het-PMMA/AMA, molar ratio of MMA/AMA = 10/1) with a carboxylic acid and a dithiobenzoate terminus was obtained using 4,4-azobis(4-cyano pentanoic acid) as initiator and 4-cyano pentanoic acid dithiobenzoate as chain transfer agent. In a second reaction step the dithiobenzoate terminus is converted to carboxylic acid groups by a radical exchange reaction. The carboxylic acid homo telechelic statistical copolymer (Ca-Hot-PMMA/AMA) is converted quantitatively by reaction with hexamethylene diisocyanate in order to form isocyanate homo telechelic copolymer (Is-Hot-PMMA/AMA). Last the obtained soft segments were used for polyurethane synthesis. The well-defined polymer structures are characterized by SEC, Raman, and 1H NMR spectroscopy.

Polymers 8(10), 372 (2016). doi:10.3390/polym8100372 special issue: "Special Issue "Enzymatic Polymer Synthesis" / Guest Editor: Dr. Katja Loos, Macromolecular Chemistry and New Polymeric Materials, Zernike Institute for Advanced Materials, University of Groningen", Published by MDPI, Basel

There is increasing interest in the synthesis of low molecular weight heparin and heparan sulfate mimetic polymers because of their various potential biomedical applications. The functional activity of heparin and heparan sulfate is believed to arise from the presence of a number of functional groups, such as hydroxyl, carboxylate and sulfate groups. The design and synthesis of novel heparin-mimetic polymers with a particular functionality poses a formidable challenge and requires carefully control of the selective conversion of functional groups on the polymer chain. Here, this study describes a simple and efficient synthetic protocol for the preparation of heparin-mimetic linear polyglycidol copolymers based on the selective conversion of primary hydroxyl groups to carboxylic acids under ruthenium-catalyzed selective dehydrogenation in basic aqueous solution. To achieve the anticoagulant activity of these polymers, primary hydroxyl groups are selectively converted to sulfate groups. The anticoagulant activity of the heparin mimics is studied by rotational thromboelastometry using EXTEM and INTEM assays. The environmentally benign process described herein provides an attractive route for the synthesis of heparin-mimetic polymers with tailored functions such as anticoagulant activity.

The synthesis of 3-allyloxymethyl-3-ethyloxetane (AllylEHO) and its polymerization with BF3 × Et2O is described in this study. Size exclusion chromatography (SEC) and membrane osmometry are used for the determination of molecular weights of the obtained products, ranging from Mn,SEC = 41,500-131,500 g/mol. 1H NMR spectroscopy, SEC, as well as MALDI-TOF MS reveal the formation of cyclic tetramer beside low, but detectable concentrations of larger cyclic oligomers as by-products during the polymerization process. These results help to understand mechanistically why attempts for a controlled homopolymerization of AllylEHO fail and why a controlled homopolymerization of oxetanes has not been described so far in the literature. Additionally, the high versatility of allyl-functional polyoxetane for postpolymerization modification is proven by thiol–ene reactions with 3-mercaptopropionic acid and N-acetyl-L-cysteine methyl ester. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Poly-N-acetyllactosamines (poly-LacNAc, [−3Gal(β1–4)GlcNAc(β1−]n) are terminal glycan structures present in glycoproteins and glycolipids. Their biological functions as ligands for galectins and as carriers of glycan epitopes are well documented. In the present paper we have characterized six novel functionalized β- d -GlcNAc derivatives, including aglyca of varying hydrophobicity and molecular weight, as substrates for recombinant human β1,4 galactosyltransferase 1 (β4GalT-1). The sugar derivatives carry short or long amino- or azide-terminated linker molecules for further modification or immobilization. The linker chemistry had an impact on enzyme kinetics and enzymatic syntheses of N-acetyllactosamine derivatives (LacNAc, Gal(β1–4)GlcNAc(β1-R). The combination of β4GalT-1 with bacterial β1,3-N-acetylglucosaminyltransferase (β3GlcNAc-T) resulted in the preparative syntheses of LacNAc oligomers with up to three LacNAc repeating units. All products were characterized by NMR and MS. The obtained LacNAc glycans were immobilized onto microtiter plates and their efficiency of binding of fungal galectin CGL2 was determined.