A new synthetic pathway of segmented tri-block copolyether

A new synthetic pathway of A–B–A tri-block copolyether which is composed of a hydrophilic poly(oxyethylene) unit as an A part and a hydrophobic poly(oxy-2-methyl-trimethylene) unit as a B part is proposed. Telechelic α-tosyl-ω-tosyloxypoly(oxy-2-methyl-trimethylene) derived from tosylation of poly(oxy-2-methyl-trimethylene glycol) (PMTG) was allowed to react with poly(ethylene glycol) (PEG) in the presence of sodium hydroxide. T_g of the resulting A–B–A tri-block copolyether (PEMG) (M?_n = 1600) was ?72°C and its specific gravity [D₄¹⁵] was 1.055.     

Synthesis of poly(ethylene glycol methyl ether)-b-poly(ethylenimine) and its derivatives containing thymine and amino acids as pendants

Poly(ethylene glycol methyl ether)tosylate was prepared and used to initiate the polymerization of 2-methyl-2-oxazoline. The resulting poly(ethylene glycol methyl ether)-b-poly(N-acetyl ethylenimine) was hydrolyzed and neutralized to give poly(ethylene glycol methyl ether)-b-poly(ethyl-enimine) (PEO–PEI). 2-(thymin-1-yl)propionic acid, N-Cbz-alanine, N-Cbz-proline, N-Cbz-O-t-Bu-serine. and N-FMOC-proline were grafted onto the PEO–PEI copolymer; attempts were then made to remove the Cbz and FMOC protecting groups.     

Counterion Exchange Selectivity in Detergent–Polymer Aggregates

In aqueous solution, the interaction between sodium dodecyl sulfate (SDS) and poly(ethylene glycol) (PEG) results in the formation of small aggregates or clusters of SDS attached to the PEG polymer chain. Selectivity coefficients for exchange of two monovalent (N-methyl-4-cyanopyridinium cation and Tl⁺) and two divalent (methylviologen cation and Cu²⁺) counterions at the surface of SDS–PEG clusters, determined employing photophysical techniques, are similar, but not identical, to those for exchange at the surface of SDS micelles in the absence of PEG. The principal factor affecting ion exchange selectivity in SDS–PEG clusters does not appear to be aggregate size or surface charge density but rather the presence of poly(oxyethylene) subunits at the aggregate surface.     

Synthesis and characterization of poly(ethylene glycol) derivatives

Five general routes for the preparation of polyoxyethylene [generally referred to as poly(ethylene glycol) or PEG] derivatives are described. These routes are (1) nucleophilic displacements with the alkoxide of PEG, (2) nucleophilic displacement on PEG–tosylate, –mesylate, or –bromide, (3) reductive amination of PEG–aldehyde, (4) reductive amination of PEG–amine, and (5) nucleophilic displacements on the s-triazine derivatives prepared from s-triazine trichloride (cyanuric chloride) and PEG. Eighteen derivatives are prepared and potential applications to catalysis, cell purifications, and other areas are discussed briefly.     

Viscoelastic properties of heterogeneous network polymers from poly(D-glutamic acid) and poly(oxyethylene glycol)

A series of five heterogeneous network polymers was prepared from poly(D -glutamic acid) (PDG) and poly(oxyethylene glycol) (PEG), and their dynamic mechanical properties were studied. The content of PDG was fixed at 60% by weight, and the molecular weight of PEG was changed to obtain networks with various crosslink densities. An increase in the PEG molecular weight from 330 to 880 caused considerable broadening of tan δ and E″ curves, and peak temperatures for tan δ and E″ decreased slightly. Curves of tan δ and E″ for PDG–PEG 4000 (indicating a PEG component of molecular weight 4,000) were much broader and the existence of two peaks was recognized. These findings and x-ray photographs suggest that PDG–PEG 330, 570, and 880 give films of fairly uniform phase, but that PDG–PEG 1830 and 4000 give films with two-phase structure. The factors influencing the dynamic mechanical properties in decreasing order of effectiveness are found to be the proportions by weight of PDG and PEG, the compatibility of PDG with PEG, the crosslink density, and the concentration of free carboxyl groups. The infrared spectra of these polymers indicate that at least part of the PDG component retains the α-helix conformation.     

Synthesis and characterization of poly(butadiene-b-sulphone) by block-copolycondensation—I. Synthesis from α,ω-dichlorocarbonyl oligobutadienes and α,ω-diphenol oligoarylethersulphones

Synthesis of poly(butadiene-b-sulphone) has been carried out by two methods. Reaction of α,ω-di(sodium phenolate) oligosulphone with α,ω-di(chlorocarbonyl)oligobutadiene or reaction of α,ω-diphenol oligosulphone with α,ω-di(chlorocarbonyl)oligobutadiene in the presence of magnesium. For both methods, the reaction was carried out between two models (bisphenol A and adipoyl chloride) or between a model and an oligomer or between two oligomers. For the first reaction a two-step process, involving the separation and the purification of the phenolate, is described: it is more efficient than the classical one-step process, where acid chloride is added in an alkaline solution of phenol. The second method, which seems never to have been used in polymer synthesis, gives better results than the first, with higher $\text{DP}{}_{\mathrm{n}}$ and less interference from side-reactions.     

Functional polymers and sequential copolymers by phase transfer catalysis. XXVIII. Synthesis and characterization of alternating block copolymers and polyformals of polyisobutylene and aromatic polyether sulfone

Alternating—i.e., -(A-B)_n- type—block copolymers of polyisobutylene (PIB) and aromatic polyether sulfone (PSU) have been prepared by phase transfer catalyzed Williamson polyetherification of α,ω-di(phenol)PIB with α,ω-di(chloroallyl)- or -(bromobenzyl)PSU. Block copolymers of the two prepolymers were also synthesized by the phase transfer catalyzed polyetherification of methylene chloride with α,ω-di(phenol)PIB and α,ω-di(phenol)PSU (bisphenol-A-terminated PSU). This method leads to -[(A)_x-(B)_y]_n- block copolymers with formal linkages between segments. At sufficiently high segment lengths, both types of block copolymers exhibit two distinct T_gs, indicating phase separation into rubbery PIB and glassy PSU domains.     

Synthesis of poly(ethylene glycol)/polypeptide/poly(D,L‐lactide) copolymers and their nanoparticles

Core‐shell structured nanoparticles of poly(ethylene glycol) (PEG)/polypeptide/poly(D ,L ‐lactide) (PLA) copolymers were prepared and their properties were investigated. The copolymers had a poly(L ‐serine) or poly(L ‐phenylalanine) block as a linker between a hydrophilic PEG and a hydrophobic PLA unit. They formed core‐shell structured nanoparticles, where the polypeptide block resided at the interface between a hydrophilic PEG shell and a hydrophobic PLA core. In the synthesis, poly(ethylene glycol)‐b‐poly(L ‐serine) (PEG‐PSER) was prepared by ring opening polymerization of N‐carboxyanhydride of O‐(tert‐butyl)‐L ‐serine and subsequent removal of tert‐butyl groups. Poly(ethylene glycol)‐b‐poly(L ‐phenylalanine) (PEG‐PPA) was obtained by ring opening polymerization of N‐carboxyanhydride of L ‐phenylalanine. Methoxy‐poly(ethylene glycol)‐amine with a MW of 5000 was used as an initiator for both polymerizations. The polymerization of D ,L ‐lactide by initiation with PEG‐PSER and PEG‐PPA produced a comb‐like copolymer, poly(ethylene glycol)‐b‐[poly(L ‐serine)‐g‐poly(D ,L ‐lactide)] (PEG‐PSER‐PLA) and a linear copolymer, poly(ethylene glycol)‐b‐poly(L ‐phenylalanine)‐b‐poly(D ,L ‐lactide) (PEG‐PPA‐PLA), respectively. The nanoparticles obtained from PEG‐PPA‐PLA showed a negative zeta potential value of ?16.6 mV, while those of PEG‐PSER‐PLA exhibited a positive value of about 19.3 mV. In pH 7.0 phosphate buffer solution at 36 °C, the nanoparticles of PEG/polypeptide/PLA copolymers showed much better stability than those of a linear PEG‐PLA copolymer having a comparable molecular weight. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of rod-coil block copolymers via end-functionalized poly(p-phenylene)s

This paper describes a new way to synthesize rod-coil block copolymers consisting of poly(p-phenylene) (PPP) as rigid rod and either polystyrene (PS) or poly(ethylene oxide) (PEO) as flexible coil. The Suzuki-coupling of the AB-type monomer 4-bromo-2,5-diheptylbenzeneboronic acid (1) under strictly proton-free conditions leads to the control of PPP endgroups and hence allows the synthesis of a variety of differently end-functionalized poly(p-phenylene)s. The poly(2,5-diheptyl-p-phenylene)-block-polystyrene (7) is then prepared via condensation via condensation of anionically polymerized living polystyrene ( 6 ) with α-(4-formylphenyl)-ω-phenyl-poly(2,5diheptyl-p-phenylene) ( 4 ). Toluenesulfonic acid catalyzed condensation of α-methyl-ω-amino-poly(oxyethylene) ( 8 ) with PPP 4 yields poly(2,5-diheptyl-p-phenylene)-block-poly(ethylene oxide) ( 9 ).     

Synthesis of poly(ethylene glycol)-functionalized hydroxyapatite organic colloid intended for nanocomposites

Traditional modifications to hydroxyapatite(HA) nanoparticles usually occurred after HA synthesis and thus are insufficient to avoid particle agglomeration.In this study,a new heterofunctional poly(ethylene glycol)(PEG) with phosphoric acid and carboxyl end groups,i.e.,α-(N-2-phosphoethyl phosphoric acid)-amide,ω-carboxyl-bismethyoxy poly(ethylene glycol)(ADP-PEG-COOH),was synthesized as an in situ surface modifier to HA nanoparticles.The resulting modified HA(ADP-PEG-HA) can disperse in methanol,forming a colloid stabilized by peripheral carboxyl-endcapped PEG chains.The colloidal particles resembled nanospheres which agglomerated to some extent under examination by transmission electron microscope.This highly dispersible HA nanoparticles in organic solvent might find application in preparing new HA nanocomposites.     

Styrene polymerization with some new macro or macromonomeric azoinitiators having peg units

Several new macroinitiators and macromerinitiators (macroinimers) were synthesized and evaluated for the bulk polymerization of sytrene at 60°C. Macroinitiators were prepared from the reaction of 4,4′-dicyano-4,4′ azovaleryl chloride ( 1 ) with poly(ethylene glycol) (PEG) with a M_ω of 400 and with either benzoyl chloride, acetyl chloride, phenyl isocyanate, or poly(ethylene glycol) oleyl ether. Macromer initiators were also prepared from the reaction of 1 with PEG having M_ω values of 200, 400, 600, 1000, or 1500 and with 4-vinylbenzyl chloride. The bulk polymerization of styrene by macroinimers gave crosslinked styrene-PEG block copolymers, while the polymerization by macroinitiators gave soluble copolymers. The molecular weights of the styrene-PEG block copolymers obtained with macroinitiators having either oleyl, benzoyl, or phenyl urethane end groups were 22000–29000 g/mol. DSC measurements showed that the crosslinked block copolymers had crystalline PEG units with melting transitions ranging from 11–37°C. © 1994 John Wiley & Sons, Inc.     

Synthesis of Heterotelechelic Poly(ethylene glycol)-block-poly(succinimide) Possessing Both Acetal and Tert-Butoxycarbonyl-amino Terminals with Narrow Molecular Weight Distribution

A novel heterotelechelic linear block copolymer of poly(ethylene glycol) (PEG) and poly(succinimide) (PSI) possessing both acetal and tert-butoxycarbonyl-amino (Boc-NH) terminals (Acetal-PEG-b-PSI-NH-Boc) with a narrow molecular weight distribution (MWD) was successfully prepared by the nucleophilic attack of triethylamine (TEA) to the poly(β-benzyl L-aspartate) (PBLA) segment of Acetal-PEG-b-PBLA-NH-Boc. Acetal-PEG-b-PBLA-NH-Boc with MWD of 1.07 was prepared by living anionic ring-opening polymerization of β-benzyl L-aspartate N-carboxy-anhydride with α-acetal-ω-amino PEG as a macroinitiator, followed by Boc protection. The subsequent conversion of PBLA segment to PSI was successfully carried out by reacting with the catalytic amount of TEA. The characterization by ¹H NMR, GPC and IR demonstrates that the formation of poly(succinimide) proceeded completely without any remarkable side reactions. Acetal-PEG-b-PSI-NH-Boc thus obtained may have a potential utility as a targetable drug carrier in the field of drug delivery system.     

Thermal and pH‐sensitive gold nanoparticles from H‐shaped block copolymers of (PNIPAM/PDMAEMA)‐b‐PEG‐b‐(PNIPAM/PDMAEMA)

Well‐defined H‐shaped pentablock copolymers composed of poly(N‐isopropylacrylamide) (PNIPAM), poly(N,N‐dimethylaminoethylacrylamide) (PDMAEMA), and poly(ethylene glycol) (PEG) with the chain architecture of (A/B)‐b‐C‐b‐(A/B) were synthesized by the combination of single‐electron‐transfer living radical polymerization, atom‐transfer radical polymerization, and click chemistry. Single‐electron‐transfer living radical polymerization of NIPAM using α,ω azide‐capped PEG macroinitiator resulted in PNIPAM‐b‐PEG‐b‐PNIPAM with azide groups at the block joints. Atom‐transfer radical polymerization of DMAEMA initiated by propargyl 2‐chloropropionate gave out α‐capped alkyne‐PDMAEMA. The H‐shaped copolymers were finally obtained by the click reaction between PNIPAM‐b‐PEG‐b‐PNIPAM and alkyne‐PDMAEMA. These copolymers were used to prepare stable colloidal gold nanoparticles (GNPs) in aqueous solution without any external reducing agent. The formation of GNPs was affected by the length of PDMAEMA block, the feed ratio of the copolymer to HAuCl₄, and the pH value. The surface plasmon absorbance of these obtained GNPs also exhibited pH and thermal dependence because of the existence of PNIAPM and PDAMEMA blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Allgemeiner Zugang zu Polyaminen mit Ethan-1,2-diamin-Einheiten: Synthese von nicht natürlich vorkommenden homologen und isomeren N1,4-Di(4-cumaroyl)sperminen

█tl="American"█The synthesis of the three N,N′-di(4-coumaroyl)tetramines, i.e., of (E,E)-N-{3-[(2-aminoethyl)amino]propyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1a ), (E,E)-N-{4-[(2-aminoethyl)amino]butyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1b ), and (E,E)-N-{6-[(2-aminoethyl)amino]hexyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1c ), is described. It proceeds through stepwise construction of the symmetric polyamine backbone including protection and deprotection steps of the amino functions. Their behavior on TLC in comparison with that of 1,4-di(4-coumaroyl)spermine (=(E,E)-N-{4-[(3-aminopropyl)amino]butyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(propane-1,3-diyl)bis[prop-2-enamide]; 2 ) is discussed.     

Functional polymers and sequential copolymers by phase transfer catalysis. 18. Synthesis and characterization of α,ω-bis(2,6-dimethylphenol)–poly(2,6-dimethyl-1,4-phenylene oxide) and α,ω-bis(vinylbenzyl)–poly(2,6-dimethyl-1,4-phenylene oxide) oligomers

A novel and convenient synthetic method for the preparation of α,ω-bis(2,6-dimethylphenol)–poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-2OH) is presented. It is based on the oxidative copolymerization of 2,6-dimethylphenol (DMP) with 2,2′-di(4-hydroxy-3,5-dimethylphenyl propane) (TMBPA) in a mixture of water–methanol or chlorobenzene–methanol. By using a 4/1 mole ratio of DMP to TMBPA and different solvent mixtures, it was possible to obtain bifunctional PPO-2OHs with number average molecular weights between 1000 and 5000. A phase-transfer-catalyzed etherification of PPO-2OH chain ends with a mixture of m- and p-chloromethylstyrene was used to synthesize α,ω-bis(vinylbenzyl)-poly(2,6-dimethyl-1,4-phenylene oxide)s (PPO-2VBs). The thermal polymerization of the PPO-2VBs was studied by differential scanning calorimetry, and has demonstrated a very high thermal reactivity for this new class of reactive oligomers.     

Preparation of polyhydrouracils and polyiminoimidazolidinones

Polyhydrouracils and polyiminoimidazolidinones were prepared by ring formation along the chain of appropriately substituted polyureas. Cyclization of 2-carbomethoxy-ethyl-substituted polyureas in a polyphosphoric acid medium gave the polyhydrouracils. The polyurea precursors were prepared from N,N′-bis(2-carbomethoxyethyl)-1,6-hexanediamine and N,N′-di(2-carbomethoxyethyl)-1,4-cyclohexanebis(methylamine) with methylenebis(4-phenyl isocyanate), 2,4-toluene diisocyanate, and 3,3′-dimethoxy-4,4′-biphenylene diisocyanate. These polyureas were soluble in m-cresol, dimethylformamide, and chloroform, had inherent viscosities of up to 0.8, and could be cast into tough films. The polyhydrouracils had similar physical properties and could also be cast into films. The polyhydrouracils melted at temperatures 100–150°C higher than their polyurea precursors. Polyiminoimidazolidinones were prepared by cyclization of α-cyanoalkyl-substituted polyureas in the presence of n-butylamine. The intermediate polyureas, which were not isolated, were prepared from methylenebis(4-phenyl isocyanate) with N,N′-bis(1-cyanocyclohexyl)-1,6-hexanediamine, N,N′-bis(1-cyanocyclohexyl)-m-xylylenediamine and N,N′-bis(1-cyanocyclopentyl)-1,6-hexanediamine. The polyiminoimidazolidinones were soluble in m-cresol, dimethylformamide, and chloroform and had low inherent viscosities of 0.14–0.28. Thermogravimetric analyses showed that the polyhydrouracils underwent rapid decomposition at 400°C, whereas an analogous unsubstituted polyurea decomposed at 300°C. On the other hand, the polyiminoimid-azolidinones showed no greater thermal stability than the unsubstituted polyurea.     

Synthesis of 1‐methoxypoly(oxyethylene)benzocyclobutene and its diels–alder reactions

A new poly(ethylene glycol) derivative, 1‐methoxypoly(oxyethylene)benzocyclobutene ( 1 ) was prepared from the reaction of 1‐benzocyclobutenyl 1‐hydroxyethyl ether with mesylate of methoxypoly(oxyethylene) in tetrahydrofuran. The degree of end‐group conversion, as determined by NMR, was 100%. The Diels–Alder reactions of 1 with maleic anhydride and N‐phenylmaleimide were carried out in refluxing toluene to obtain the corresponding adducts ( 2 and 3 , respectively) in excellent yields. NMR analyses of 2 and 3 indicated complete conversion of 1 to the corresponding products. The reaction of 2 with o‐toluidine resulted in complete conversion of the anhydride adduct to the corresponding products. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1934–1938, 2004     

Synthesis of amphiphilic and thermoresponsive ABC miktoarm star terpolymer via a combination of consecutive click reactions and atom transfer radical polymerization

Well‐defined amphiphilic and thermoresponsive ABC miktoarm star terpolymer consisting of poly(ethylene glycol), poly(tert‐butyl methacrylate), and poly(N‐isopropylacrylamide) arms, PEG(‐b‐PtBMA)‐b‐PNIPAM, was synthesized via a combination of consecutive click reactions and atom transfer radical polymerization (ATRP). Click reaction of monoalkynyl‐terminated PEG with a trifunctional core molecule bis(2‐azidoethyl)amine, (N₃)₂? NH, afforded difunctional PEG possessing an azido and a secondary amine moiety at the chain end, PEG‐NH? N₃. Next, the amidation of PEG‐NH? N₃ with 2‐chloropropionyl chloride led to PEG‐based ATRP macroinitiator, PEG(? N₃)? Cl. The subsequent ATRP of N‐isopropylacrylamide (NIPAM) using PEG(? N₃)? Cl as the macroinitiator led to PEG(? N₃)‐b‐PNIPAM bearing an azido moiety at the diblock junction point. Finally, well‐defined ABC miktoarm star terpolymer, PEG(‐b‐PtBMA)‐b‐PNIPAM, was prepared via the click reaction of PEG(? N₃)‐b‐PNIPAM with monoalkynyl‐terminated PtBMA. In aqueous solution, the obtained ABC miktoarm star terpolymer self‐assembles into micelles consisting of PtBMA cores and hybrid PEG/PNIPAM coronas, which are characterized by dynamic and static laser light scattering, and transmission electron microscopy. On heating above the phase transition temperature of PNIPAM in the hybrid corona, micelles initially formed at lower temperatures undergo further structural rearrangement and fuse into much larger aggregates solely stabilized by PEG coronas. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4001–4013, 2009     

Synthesis and dynamic mechanical properties of heterogeneous network polymers from poly(L-glutamic acid) and poly(oxyethylene glycol)

Heterogeneous network polymers composed of rigid polypeptide chains and flexible polyether chains were synthesized. That is, poly(L -glutamic acid) (PLGA) was crosslinked with poly(oxyethylene glycol) (PEG) at various carboxy/hydroxyl mole ratios K. The solubility tests and hydrolysis of heterogeneous network polymers suggest that the crosslinking reaction proceeds by esterification. The dynamic mechanical properties of these polymers(100 Hz, ?100–200°C) are greatly influenced by the presence of a trace of water and the weight per cent of PLGA. In addition, some of these polymers show only one maximum in the temperature dispersion of dynamic loss modulus E″ and tan δ, although their shape is rather broad. The x-ray photographs of these polymers show an amorphous halo or weak Debye-Sherrer rings. These findings suggest that these polymers are not simple adducts; neverthless PLGA and/or PEG domains exist.     

Synthesis of 6-cyanopurines and the isolation and X-ray structure of novel 2H-pyrroles

(Z)-N¹-(2-Amino-1,2-dicyanovinyl)-N²-substituted-formainidines react with dimethylformamide diethyl acetal at room temperature to give 6-cyanopurines as the major product together with novel 5-amino-2-arylimino-3,4-di[(N,N-dimethylamino)methylideneamino]-2H-pyrroles, which have been fully characterised and a single crystal X-ray analysis has been carried out on the N-phenyl derivative.