Enhanced biocompatibility in biostable poly(carbonate)urethane

In this work, we synthesized two MDI-based polyurethanes, including a poly(ether)urethane (PEU) and a poly(carbonate)urethane (PCU), by using different soft segments, poly(tetramethylene oxide) and poly(hexyl, ethyl)carbonate diol (M approximately 2,000). We demonstrated that, in addition to the enhanced biostability of PCU over PEU, the biological performances of PCU in vitro were also improved in general. These included, better cellular attachment and proliferation, less platelet activation, as well as reduced monocyte activation. The unusual wide-ranging enhancement in biocompatibility for PCU was believed to be related to the larger micro-phase separation in PCU (approximately 25 nm) that caused distinct protein adsorption on the surface. The total number of adherent monocytes (nonactivated and activated) on the bare sample surfaces, albumin pre-adsorbed sample surfaces, and fibrinogen pre-adsorbed sample surfaces.     

Cell attachment and proliferation on poly(carbonate urethanes) with various degrees of nanophase separation

In this work, we synthesized six 4,4'-diphenylmethane diisocyanate (MDI)-based poly(carbonate urethanes) (PCU) by using the macrodiol poly(1,6-hexyl, 1,2-ethyl carbonate) diol (MW = 2,017) in different molar ratios to MDI. The bulk and surface properties of cast PCU films were analyzed. The glass transition temperatures measured by dynamic mechanical analysis (DMA) and surface images obtained from atomic force microscopy (AFM) indicated that these PCU had various degrees of nanophase separation that changed with the time and film casting temperatures. The degree of nanophase separation correlated very well with endothelial cell attachment and proliferation on PCU.     

单组分聚氨酯清漆的制备与性能研究

不同的聚碳酸酯二元醇、聚四亚甲基醚二醇(PTMG)与二苯甲烷二异氰酸酯(MDI)、小分子二元醇反应,制得聚醚、聚碳酸酯型聚氨酯清漆。通过红外光谱分析结合其机械力学性能、耐水性等的测试结果,探讨聚碳酸酯型聚氨酯清漆的结构对形态和性能的影响。结果表明：随着硬段含量的增加,树脂涂膜的微相分离程度增加,机械性能提高;组分摩尔比例相同时,软段分子量的降低有利于提高树脂的软硬段相容性,增加树脂涂膜的物理机械性能;组分摩尔比例相同时聚酯型聚氨酯树脂的微相分离程度低于聚醚型聚氨酯树脂;MDI基溶剂型聚氨酯树脂的物理机械性能较好。     

Synthesis and properties of poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties

Poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties (poly(HC‐MDI)) was prepared by polyaddition of 4,4′‐diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3‐hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six‐membered spiroorthocarbonate 1,5,7,11‐tetraoxa‐spiro[5.5]undecane. The polyaddition proceeds without concomitant side reactions including carbonate exchange reaction and affords the desired poly(carbonate‐urethane). The hydrolysis and thermal behaviors of poly(HC‐MDI) were compared with those of the analogous polyurethane carrying no carbonate structure (poly(ND‐MDI)) prepared from MDI and 1,9‐nonanediol (ND). Although the glass transition behaviors are almost identical, poly(HC‐MDI) is less crystalline than poly(ND‐MDI). Poly(HC‐MDI) is more susceptible to hydrolysis than poly(ND‐MDI) probably due to the higher polarity and the lower crystallinity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2802–2808, 2006     

Biocompatibility of poly(carbonate urethane)s with various degrees of nanophase separation

Nanophase separation has been suggested to influence the biological performance of polyurethane. In a previous work, six different 4,4'-diphenylmethane diisocyanate (MDI)-based poly(carbonate urethane)s (PCUs) that exhibited various degrees of nanophase separation were synthesized and characterized. In the present work, these PCUs were used as a model system to study the effect of nanometric structures on the biocompatibility of polyurethane. Human blood platelet activation, monocyte activation, protein adsorption, and bacterial adhesion on PCU were investigated in vitro. It was found that human blood platelets as well as monocytes were less activated on the PCU surfaces with a greater degree of nanophase separation in general. This phenomenon was closely associated with the lower ratio of human fibrinogen/albumin competitively adsorbed on these surfaces. Bacterial adhesion was also inhibited in some nanophase-separated PCUs. [diagram in text].     

Study of phase separation in polyurethane using paramagnetic labels. Effect of soft segment molecular weight,structure, and thermal history

The morphology of segmented polyurethane (PU) elastomers was studied by means of ESR at various temperatures ranging from 100K-450K. The PU's were based on 4,4'-diphenylmethane diisocyanate (MDI), poly (oxytetramethylene) glycols (PTMO) and hydroxyl-terminated random compolymers of tetrahydrofuran and 3-methyl-tetrahydrofuran (THF/Me-THF). Purified 1,4-butanediol (BD) was used as a chain extender. The nitroxide probe, 4-hydroxy-2-2',6-6'-tetramethylpiperidine-1-oxyl (TEMPOL), was used to label the polyurethanes by reaction with an NCO group of MDI. Analysis of the electron spin resonance (ESR) spectra suggested that the label situates at heterogeneous sites, which means that a two-phase domain is present. The morphologies at 300K and 400K were compared. It was found from ESR spectra that polyurethanes made from soft segments having higher MW exhibited greater phase separation at 300K than their corresponding elastomers made from lower MW soft segments. However, at 400K the more isotropic ESR spectra for the PUs containing higher MW soft segments suggested that the PUs were more mobile than their analogs having lower MW soft segments. The introduction of 3-methyl side groups decreased the phase mixing at 400K due to steric hindrance.     

Self-organization in aqueous solutions of thermosensitive statistical copolymers based on N-(dimethylamino)ethyl methacrylate

Thermo- and pH-responsive statistical copolymers of N-(dimethylamino)ethyl methacrylate and lauryl methacrylate were synthesized by free radical copolymerization. Obtained samples differed in content of hydrophobic components (3 and 6?mol. %). Their molar masses were close to 30,000?g/mol. Self-organization in buffer solutions of copolymers were studied using light scattering and turbidimetry. It was found that copolymers as well as of poly(N-(dimethylamino)ethyl methacrylate) were thermosensitive at pH?>?7. Phase separation temperatures of investigated solutions decreased with dilution and pH increasing. Growth of lauryl methacrylate content in copolymers caused the decrease in phase separation temperatures.     

Microphase Separation of Bulk and Ultrathin Films of Polyurethane Elastomers

Surmmary: Polyurethane elastomers (PUEs) were synthesized with poly(oxytetramethylene) glycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD)/1,1,1-trimethylol propane (TMP) by a prepolymer method. The degree of microphase separation of bulk and ultrathin films for these PUEs was confirmed by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and atomic force microscopy (AFM). In the bulk films, FT-IR and DSC measurements revealed that the degree of micro-phase separation strengthened with increasing BD content. AFM observation of the BD-PUE showed hard segment domains surrounded by a soft segment matrix. The domains ranged in size from 10-20 nm, while BD/TMP- and TMP PUEs did not have clear domains. On the other hand, AFM observation was carried out on thin films (200 mm in thickness) and ultrathin films (approximately 8-5 nm) prepared by spin-coating the different concentrations of PUE solutions. The microphase separated strucuture under 10 nm in thickness showed marked decreases in the size of the microphase-separated domain.     

Shape memory polyurethanes based on recycled polyvinyl butyral. I. Synthesis and morphology

Shape memory polyurethanes (SMPUs) were synthesized by 4,4′-diphenylmethane diisocyanate (MDI), hexane-1,6-diol (HD), polypropylene glycol (PPG), and recycled polyvinyl butyral (PVB). Dynamic mechanical analysis, differential scanning calorimetry and Fourier transformation infrared attenuated total reflection spectroscopy was used to characterize the poly (vinylbutyral-urethanes). Micro-phase domain separation of hard and soft segments and phase inversion were investigated. Increasing the hard segment content, i.e., average hard segment molecular weight, leads to an increase in the degree of micro-phase separation, hard domain order and crystallinity. The crystalline hard segment structures combined with the elastic nature of soft segment matrix provide enough physical and chemical crosslinks to have shape memory effect.     

Semi‐micro reversed‐phase liquid chromatography for the separation of alkyl benzenes and proteins exploiting methacrylate‐ and polystyrene‐based monolithic columns

Monolithic columns were synthesized inside 1.02 mm internal diameter fused‐silica lined stainless‐steel tubing. Styrene and butyl, hexyl, lauryl, and glycidyl methacrylates were the functional monomers. Ethylene glycol dimethacrylate and divinylbenzene were the crosslinkers. The glycidyl methacrylate polymer was modified with gold nanoparticles and dodecanethiol (C₁₂). The separation of alkylbenzenes was investigated by isocratic elution in 60:40 v/v acetonitrile/water. The columns based on polystyrene‐co‐divinylbenzene and poly(glycidyl methacrylate)‐co‐ethylene glycol dimethacrylate modified with dodecanethiol did not provide any separation of alkyl benzenes. The poly(hexyl methacrylate)‐co‐ethylene glycol dimethacrylate and poly(lauryl methacrylate)‐co‐ethylene glycol dimethacrylate columns separated the alkyl benzenes with plate heights between 30 and 60 μm (50 μL min^?1 and 60°C). Similar efficiency was achieved in the poly(butyl methacrylate)‐co‐ethylene glycol dimethacrylate column, but only at 10 μL min^?1 (0.22 mm s^?1). Backpressures varied from 0.38 MPa in the hexyl methacrylate to 13.4 MPa in lauryl methacrylate columns (50 μL min^?1 and 60°C). Separation of proteins was achieved in all columns with different efficiencies. At 100 μL min^?1 and 60°C, the lauryl methacrylate columns provided the best separation, but their low permeability prevented high flow rates. Flow rates up to 500 μL min^?1 were possible in the styrene, butyl and hexyl methacrylate columns.     

Synthesis and characterization of hydrolysable poly(ether-urethane-urea)s derived from l-leucine anhydride cyclopeptide; a green synthetic method for monomer

l-leucine anhydride cyclodipeptide (LAC) was prepared through a green method under microwave irradiation with good yield. Then a new class of hydrolysable poly(ether-urethane-urea)s (PEUUs) was synthesized via two-step polymerization method. In the first step, 4,4′-methylene-bis-(4-phenylisocyanate) (MDI) was reacted with LAC to produce isocyanate-terminated poly(imide-urea) oligomers (hard segment). Reaction of the resulting pre-polymer with different molecular weights (MW) of polyethyleneglycols (PEG)s such as PEG-400, PEG-600, PEG-1000 and PEG-2000 was the second step to furnish a series of new PEUUs. The resulting multiblock copolymers have inherent viscosities in the range of 0.4-1.8 dL/g. These multiblock copolymers are hydrolysable, thermally stable and soluble in amide-type solvents. Polymers containing different molecular weights of PEGs soft segments show different thermal stability, phase separation, hard segment cohesiveness and hydrolysis rate. Some structural characterization and physical properties of these PEUUs are reported.     

A combinatorial approach to studying the effects of N-alkyl groups on poly(N-alkyl and N,N-dialkylacrylamide) solubility

Soluble polymers including poly(N-alkylacrylamide)s with low mole percent loadings of pendant groups are of interest in applications in catalysis, synthesis, sequestration, and soluble affinity chromatography where their thermal and phase-dependent solubility facilitates purification and separation. This work describes a library synthesis and study of the effects of polymer composition on the phase-selective solubility of dye-labeled poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers. To study the relative importance of n-octadecyl versus n-butyl groups, copolymers with different ratios of n-octadecylacrylamide and n-butylacrylamide but with similar degrees of polymerization and polydispersity were prepared by a split-pool synthesis using a highly soluble poly(N-acryloxy-2-dodecylsuccinimide) as the precursor. Polymer sequestrants were used to remove excess amines and the byproduct N-hydroxyl-2-dodecylsuccinimide without fractionation of the polyacrylamides. Other studies of dye-labeled poly(N,N-dialkylacrylamide)s prepared by the polymerization of N,N-dialkylacrylamides with methyl, ethyl, propyl, butyl, pentyl, and hexyl N-alkyl groups in a variety of thermomorphic or latent biphasic polar/nonpolar solvent mixtures showed that poly(N,N-dialkylacrylamide)s like poly(N-alkylacrylamide)s have phase-selective solubility that is highly dependent on the size of the N-alkyl group.     

Influence of stereoregularity and linkage groups on chiral recognition of poly(phenylacetylene) derivatives bearing L‐leucine ethyl ester pendants as chiral stationary phases for HPLC

Stereoregular poly(phenylacetylene) derivatives bearing L ‐leucine ethyl ester pendants, poly‐1 and poly‐2a , were, respectively, synthesized by the polymerization of N‐(4‐ethynylphenylcarbamoyl)‐L ‐leucine ethyl ester ( 1 ) and N‐(4‐ethynylphenyl‐carbonyl)‐L ‐leucine ethyl ester ( 2 ) using Rh(nbd)BPh₄ as a catalyst, while stereoirregular poly‐2b was synthesized by solid‐state thermal polymerization of 2 . Their chiral recognition abilities for nine racemates were evaluated as chiral stationary phases (CSPs) for high‐performance liquid chromatography (HPLC) after coating them on silica gel. Both poly‐1 and poly‐2a with a helical conformation showed their characteristic recognition depending on coating solvents and the linkage groups between poly(phenylacetylene) and L ‐leucine ethyl ester pendants. Poly‐2a with a shorter amide linkage showed higher chiral recognition than poly‐1 with a longer urea linkage. Coating solvents played an important role in the chiral recognition of both poly‐1 and poly‐2a due to the different conformation of the polymer main chains induced by the solvents. A few racemates were effectively resolved on the poly‐2a coated with a MeOH/CHCl₃ (3/7, v/v) mixture. The separation factors for these racemates were comparable to those obtained on the very popular CSPs derived from polysaccharide phenylcarbamates. Stereoirregular poly‐2b exhibited much lower chiral recognition than the corresponding stereoregular, helical poly‐2a , suggesting that the regular structure of poly(phenylacetylene) main chains is essential to attain high chiral recognition. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Self Organization and Redox Behavior of Poly(vinylferrocene)-block-Poly(isobutylene)-block-Poly(vinylferrocene) Triblock Copolymer †

Self organization and redox behavior of a ferrocene containing triblock copolymer, poly(vinylferrocene)-block-poly(isobutylene)-block-poly(vinylferrocene), with narrow molecular weight distribution in solutions and in thin films were investigated. Dynamic light scattering studies of the block copolymer in dilute solutions indicated that the polymer chains aggregated at relatively low concentrations. The aggregations of polymer chains were observed in toluene, as well as in tetrahydrofuran at concentrations as low as 0.014 mg/mL and 0.0045 mg/mL, respectively. Thin films of the copolymer showed reversible single electron redox behavior, similar to that of ferrocene. Morphology and micro-phase separation of the copolymer was analyzed by transmission electron microscopy.     

Synthesis and characterization of poly(urethane-sulfone)s

Eight poly(urethane-sulfone)s were synthesized from two sulfone-containing diols, 1,3-bis(3-hydroxypropylsulfonyl)propane (Diol-333) and 1,4-bis(3-hydroxypropylsulfonyl)butane (Diol-343), and three diisocyanates, 1,6-hexamethylene diisocyanate (HMDI), 4,4′-diphenylmethane diisocyanate (MDI), and tolylene diisocyanate (TDI, 2,4- 80%; 2,6-20%). As a comparison, eight polyurethanes were also synthesized from two alkanediols, 1,9-nonanediol and 1,10-decanediol, and three diisocyanates. Diol-333 and Diol-343 were prepared by the addition of 1,3-propanedithiol or 1,4-butanedithiol to allyl alcohol and subsequent oxidation of the resulting sulfide-containing diols. The homopoly(urethanesulfone)s from HMDI and MDI are semicrystalline, and are soluble in m-cresol and hot DMF, DMAC, and DMSO. The copoly(urethane-sulfone)s from a 1/1 molar ratio mixture of Diol-333 and Diol-343 with HMDI or MDI have lower crystallinity and better solubility than the corresponding homopoly(urethane-sulfone)s. The poly(urethane-sulfone)s from TDI are amorphous, and are readily soluble in m-cresol, DMF, DMAC, and DMSO at room temperature. Differential scanning calorimetry data showed that poly(urethane-sulfone)s have higher glass transition temperatures and melting points than the corresponding polyurethanes without sulfone groups. The rise in glass transition temperature is 20–25°C while the rise in melting temperature is 46–71°C. © 1994 John Wiley & Sons, Inc.     

Bio-based and Biodegradable Electrospun Fibers Composed of Poly(L-lactide) and Polyamide 4

Novel bio-based and biodegradable block copolymers were synthesized by "click" reaction between poly(L-lactide)(PLLA) and polyamide 4(PA4). Upon tuning the molar mass of PLLA block, the properties of copolymers and electrospun ultrafine fibers were investigated and compared with those of PLLA and PA4 blends. PLLA and PA4 were found incompatible and formed individual crystalline regions, along with reciprocal inhibition in crystallization. Electrospun fibers were highly hydrophobic, even if hydrophilic PA4 was the rich component. The crystallinity of either PLLA or PA4 decreased after electrospinning and PLLA-rich as-spun fibers were almost amorphous. Immersion tests proved that fibers of block copolymers were relatively homogeneous with micro-phase separation between PLLA and PA4. The fibrous structures of copolymers were different from those of the fibers electrospun from blends, for which sheath-core structure induced by macro-phase separation between homopolymers of PLLA and PA4 was confirmed by TEM, EDS, and XPS.     

Graft interpenetrating polymer networks composed of epoxy resin and urethane acrylate resin

For enhancing the interpenetratoin and/or compatibility of the simultaneous interpenetrating networks (SINs) composed of epoxy resin (epoxy) and urethane acrylate resin (UAR), the graft epoxy consisting of different lengths of poly(oxypropylene) (PO) side chains were synthesized and characterized. It was found that the graft epoxy composed of short PO side chains [MW 480, epoxy-g-PO(480)] showed a compatible system while if consisting of longer PO grafts [MW 950, epoxy-g-PO(950)] exhibited a partial microphase separation morphology. DSC measurements as well as the SEM or TEM observation indicated that the interpenetration between the two phases for epoxy/UAR SINs including epoxy-g-PO(480) was improved appreciably due to the excellent miscibility between the PO grafts and PO segments existing in the graft epoxy and the UAR network, respectively. In this case, for SIN(80/20) containing 10 wt % of epoxy-g-PO(480) the tensile strength increases by a factor of 2.70 compared with that of pure epoxy network. However, the improvement of interpenetration and/or compatibility between the two networks as well as the mechanical properties for SINs composed of epoxy-g-PO(950) are limited resulting in the partial microphase separation of epoxy-g-PO(950) network's own self. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3568–3574, 1999     

Liquid chromatography of polymer mixtures applying a combination of exclusion and full adsorption mechanisms. 5. Six-component blends of chemically similar polymers

The separation of six-component blends of chemically similar homopolymers utilising the full adsorption-desorption (FAD) process is presented. The main advantage of the FAD approach over other methods represents the successive and independent size- exclusion chromatography (SEC) characterisation of all blend components. The method is based on the full adsorption and retention of all n or n−1 components of the polymer blend from an adsorption promoting liquid (ADSORLI) in a small FAD column. Nonadsorbed macromolecules are forwarded directly into SEC for molecular characterisation. Next, appropriate displacers are successively applied to the FAD column to selectively release preadsorbed blend constituents into the on-line SEC column. Dynamic integral desorption isotherms for single constituents, as well as for polymer blends to be analysed, allow identification of optimal displacer compositions to release just one kind of macromolecule. Model polymer blends containing polystyrene (PS), poly(lauryl methacrylate), poly(butyl methacrylate), poly(ethyl methacrylate), poly(methyl methacrylate) and poly(ethylene oxide) (PEO) or, alternatively, PS, poly(2-ethylhexyl acrylate), poly(butyl acrylate), poly(ethyl acrylate), poly(methyl acrylate) and PEO of similar molar masses can be separated and characterised in one multistep run using nonporous silica FAD packing, toluene as an ADSORLI and its mixtures with a desorption promoting liquid such as ethyl acetate, tetrahydrofuran or dimetylformamide to form displacers with appropriate desorption strength. Received: 9 September 1998 Accepted in revised form: 16 November 1998     

链结构及频率对嵌段聚醚氨酯介电谱的影响

不少研究者用介电驰豫的方法对聚合物进行了广泛的研究^[1-5].对多嵌段的两相体系,介电驰豫的方法很灵敏.我们曾用此法研究了不同扩链剂及软段为聚四亚甲基醚二醇(PTMG)嵌段聚醚氨酯(SPEU)的分子运动,观察到软段结晶的α_c峰^[6].本文用介电驰豫方法进一步考察软段链结构不同对温度谱的影响,以及不同驰豫单元的活化能.     

Asymmetrical flow field-flow fractionation coupled with multi-angle light scattering and refractive index detections for characterization of ultra-high molar mass poly(acrylamide) flocculants

The molar mass distributions of ultra-high molar mass polyacrylamide-based flocculants were measured using asymmetrical flow field-flow fractionation (AFFFF) coupled with multi-angle light scattering and refractive index detectors. The mass load onto the separation channel was found to be critical in obtaining a good size separation. The detailed investigation with ultra-high molar mass polyacrylamides found that the injected amount should be 相似文献