Macromolecules with specific constitution and supramolecular structures

Segmented triblock and multiblock copolymers consisting of highly flexible polydisperse segments and molecularly uniform segments of well defined architecture capable of either the formation of a mesophase, chainfolded crystallites or double-helical metal complexes have been synthesized; the bulk superstructure as well as the physical and material properties correlated with the primary structure: block copolymers with liquid crystalline segments formed microphase separated systems, and the phase behaviour depended on the constitutional composition. Multiblock copolymers with symmetrically chain-folded polyurethane hard segments and associative groups in the chain fold led to specially shaped lamellar superstructures. Block copolymers with bipyridine containing segments gave tetracoordinated and double-helical copper(I) complexes which segregated resulting in supramolecular polymer systems.     

Control of hard segment size in polyurethane formation

In general, segmented polyurethane elastomers are prepared by reacting an isocyanate-capped polyol prepolymer with a short-chain diol chain extender, yielding an elastomer with hard segments of uniform size. However, the hard segment size will not be uniform if the polyurethane polymer is prepared by forming the hard segment first, followed by soft segment formation. Because the mechanical properties of polyurethane elastomers depend on the relative ratio of the hard to soft segments as well as the effectiveness of the hard segment as a physical crosslinker, the control of the size distribution of the hard segment is a key factor in designing polyurethane elastomers. It was found that reaction conditions can affect the size distribution of hard segments derived from an aliphatic diisocyanate with differential reactivity between the two isocyanate groups. Lower reaction temperatures and simultaneous mixing of all reactants gave the preferred size distribution of hard segments. © 1995 John Wiley & Sons, Inc.     

Dynamic mechanical properties of poly-ether-urethane elastomers with chain-extended or chain-folded molecularly uniform poly (N-alkylurethane) hard segment domains

Segmented polyetherurethanes with distinctively different morphologies, i.e., with chain-extended or chain-folded crystallized hard segments, could be created by small constitutional changes in the hard segment architecture. The different superstructure was achieved by building-in specially designed constitutional units in the middle of the otherwise regularly built hard segment which for flexibility or sterical reasons allowed an adjacent reentry chain-folded and/or chain-extended crystallization of the hard phase forming polyurethane segments. The material properties of the thermoplastic elastomers correlated systematically with the hard domain superstructure which was determined by the primary structure of the macromolecule and could be reversibly altered by the thermal history in the case of the flexible center unit. The softening temperature was determined by the hard domain height of the chain-folded lamellar or the chain-extended cylindrical domains; variation of the modulus in the elastomeric region could be related to imperfections in the hard segment packing which affected the effective hard domain filler.     

1,5-萘二异氰酸酯与1,4-丁二醇基为基质的多嵌段聚氨酯弹性体的合成与性能

利用 1 ,5_萘二异氰酸酯 (NDI)和 1 ,4_丁二醇 (BDO)为均匀硬质分子单体 ,与不同软质分子单体 (聚醚、聚酯、聚硅氧烷 )缩合制备多嵌段聚氨酯弹性体 ,详细研究了硬嵌段相 (NDI)弹性体的结构与性能间的关系 ,发现随着硬嵌段相长度的增加 ,或者氨基甲酸酯中胺基与聚醚、聚酯、聚硅氧烷中软段氧原子间氢键的减弱 ,都导致微相分离程度的增加 ,造成聚合物熔点和熔化热的升高。硬嵌段相熔化的多峰行为是由于形成了NDI/BDO半微晶区 ,在退火时转变为更加有序的结晶微区 ,当温度高于 1 80℃时 ,由于氢键的断裂 ,NDI/BDO硬嵌段发生分解反应 ,该过程源于不很有序的硬嵌段半结晶微区。当温度高于 2 5 0℃时 ,发生快速的分解。在动态力学行为方面 ,NDI基聚醚弹性体比其它硅氧烷基的弹性体展示了更高的硬嵌段区的稳定性 ,同时 ,在使用温度范围内 ,也显示出最高的储能模量值 ,表明刚性对温度的依赖性 ,以及NDI/BDO硬嵌段中活性填料的显著影响     

聚丙烯与聚酯-聚醚多嵌段共聚物共混的研究

聚丙烯和聚酯-聚醚多嵌段共聚物的熔融共混物是微多相分散体系,其力学性能和软链段的结构有关。DSC和偏光显微镜图分别表明共混物中聚丙烯结晶度以及球晶尺寸随聚酯-聚醚的混入量而变小。聚丙烯和少量聚酯-聚醚多嵌段共聚物共混,可改进聚丙烯的流变性,吸湿性和染色性。     

Superstructure in segmented polyether–urethanes

The morphology of several series of segmented polyether–urethanes was studied. The “hard” segments contained urethane and urea linkages formed by 4,4′-dicyclohexylmethane diisocyanate (Hylene W) and selected aliphatic and aromatic monomeric diamines (DA). The “soft” segments were composed of oligomeric poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), or both PEO and PPO. For studying the composition–morphology relationships, the molecular weight and relative content of PEO, and the relative content of PPO were varied systematically. Different diamines were used as chain extenders. The methods of wide-angle x-ray diffraction (WAXD), small-angle x-ray scattering (SAXS), polarizing microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) were employed in the investigation. The effects of PEO content on domain formation were very significant. Calculations based on a highly simplified model indicated that, for two adjacent molecules, if two hard segments are associated with each other, the probability for the association of the next two hard segments varies inversely with the third power of soft segment length. Copolymers composed of both POE and PPO displayed enhanced domain and anisotropic superstructure. The phenomenon was interpreted in terms of polymer incompatibility. The effects on morphology of different DA's as chain extenders were tentatively accounted for by the symmetry, hydrogen bonding, and rigidity of the hard segments as well as their incompatibility with the soft segments. The formation and deformation of superstructure were of particular interest. A model was proposed to account for the formation of the resultant anisotropic structure and mechanical properties.     

Polydimethylsiloxane–polyurethane elastomers: Synthesis and properties of segmented copolymers and related zwitterionomers

A series of polyurethane block polymers based on hydroxybutyl-terminated polydimethyl-siloxane soft segments of molecular weight 2000 were synthesized. The hard segments consisted of 4,4′-methylenediphenylene diisocyanate (MDI) which was chain extended with either 1,4-butanediol (BD) or N-methyldiethanolamine (MDEA). The MDEA-extended materials were ionized by using 1,3-propane sultone. The weight fraction of hard segments was in the range 0.13–0.39. The morphology and properties of these polyurethane elastomers were studied by a variety of techniques. All of these short-segment block copolymers showed nearly complete phase separation. The zwitterionomer materials exhibited ionic aggregation within the hard domains. Hard-segment crystallinity or ionic aggregation did not affect the morphology. Hard-domain cohesion was found to be a more important factor than hard-domain volume fraction in determining the tensile and viscoelastic properties of these elastomers.     

Synthesis of new siloxane urethane block copolymers and their properties

Siloxane urethane block copolymers were prepared with siloxanes as the soft segment. Films were cast from a variety of solvents. Solvent has an effect on the segregation of soft and hard segments. Surface studies, including ESCA, EDS, and FT-IR, show well segregated block copolymers with enhanced siloxane on the surface. DSC studies show a low mp (-44°C) for the soft segment and a T_g for the hard segment above room temperature. These materials show higher thermal stability compared to polyether urethane block copolymers. These copolymers also show relatively good resistance to exposure to oxygen plasma and show improved flame retardancy compared to nonsiliconated, polyether polyurethane block copolymers. © 1994 John Wiley & Sons, Inc.     

Poly(chloropropylmethyl-dimethylsiloxane)–polyurethane elastomers: Synthesis and properties of segmented copolymers and related zwitterionomers

A series of polyurethane block copolymers based on hydroxybutyl terminated poly(chloropropylmethyl-dimethylsiloxane) and poly(tetramethylene oxide) soft segments of molecular weights 2100 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′-methylenediphenylene diisocyanate (MDI) that was chain extended with either 1,4-butanediol (BD) or N-methyldiethanolamine (MDEA). The materials chain extended with MDEA were ionized using 1,3-propane sultone. The weight fraction of the hard segments was in the range 0.30–0.45. The effect of mixed soft segments, chain extenders, and zwitterionization on the extent of phase separation and physical properties was studied by utilizing differential scanning calorimetry and dynamic mechanical, stress-strain, and Fourier Transform Infrared spectroscopy experiments. All of these short segment block copolymers showed nearly complete phase separation. The zwitterionomer materials exhibited ionic aggregation within the hard domains. Although hard segment crystallinity or ionic aggregation did not affect the morphology, hard domain cohesion was important in determining the tensile and viscoelastic properties of these elastomers.     

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。     

Polyurethane cationomers with pendant trialkylammonium groups: Effects of ion content,alkyl group,and neutralizing anion

Diphenylmethane-4,4′-diisocyanate based polyether polyurethane cationomers were synthesized using 3-trialkylammonium-(1,2-propanediol)iodide (TAPI) as the chain extender. The ionic content was varied by substituting up to 100% of 3-dialkylamino-1,2-propanediol (DAP) for TAPI. Cationomers with bromine and chlorine ions were prepared from the iodine-based polymer via ion exchange. The morphology and properties of the cationomers were studied as a function of alkyl group, ion content, and anion type using small-angle x-ray scattering, tensile testing, dynamic mechanical thermal analysis, and differential scanning calorimetry. The bulky side groups of DAP and TAPI prevented crystallization in the hard domains, and consequently little or no phase separation was evident in the unionized materials. Polyurethanes with cationic functionality showed dramatic improvements in phase separation and tensile properties. Results suggest tht while ionic interactions are the primary driving force for phase separation, they produce a morphology not typical of ionomers, but rather akin to that of a conventional polyurethane with semicrystalline hard segments. © 1994 John Wiley & Sons, Inc.     

Novel nanomicelles originating from hydroxyethyl starch-g-polylactide and their release behavior of docetaxel modulated by the PLA chain length

A novel drug carrier was synthesized through grafting polymerization of hydroxyethyl starch (HES) and d,l-lactide. By changing the molar ratio of HES and d,l-lactide, HES-g-PLA copolymers with different chain lengths of PLA can be obtained. Their chemical structures were characterized by FT-IR and ¹H NMR. Through self-emulsification combined with solvent evaporation, HES-g-PLAs self-assembled into micelles with uniform sizes ranging from 65 to 130 nm, depending upon the chain length of PLA. In vitro release profiles of docetaxel-loaded HES-g-PLAs meet first-order release kinetics via a mechanism of diffusion and polymer chain relaxation. The size of the micelles and the amount of drug loading can be controlled by varying the chain length of PLA. Another significant result is that release rates of docetaxel can be also modulated by changing the chain lengths of the PLA segments.     

不同软段结构聚氨酯-酰亚胺嵌段共聚物的合成及热性能研究

用二步法合成了不同软段 (PPO ,PEG ,PEPA)聚氨酯 酰亚胺 (PUI)嵌段共聚物 ,FTIR光谱表征了所有合成PUI分子主链均含有酰亚胺链段 ,并研究了PUI嵌段共聚物的热性能受软段类型及长度的影响 .DSC研究表明聚酯型PUI的软硬段之间的相容性比聚醚型PUI好 ,随相同软段分子量的增加 ,PUI体系的软硬段兼容性变差 ,并显示了相分离的特征 ;热失重 (TGA)研究得出不同软段的PUI样品的热稳定性大小顺序为 :PEPA PUI >PEG PUI>PPO PUI ;动态力学 (DMTA)研究给出了所合成的PUI样品在 5 0～ 2 0 0℃范围内均出现了较长的模量平台显示出有较好的耐热性 ,且随硬段含量的升高其储能模量不断增强     

开环易位聚合合成瓶刷聚合物

瓶刷聚合物是一类具有独特侧链结构的梳形聚合物。功能性瓶刷聚合物在光子晶体、表面活性剂、医药载体、防污涂层以及智能材料等领域具有良好的应用价值。通过开环易位聚合合成瓶刷聚合物的方法具有合成步骤简单、聚合物接枝密度高和侧链组成均一等优点,在控制聚合物组成、分子量和分散性等方面具有显著优势。本文基于开环易位聚合,简述了合成瓶刷均聚物以及嵌段型、混合型和核-壳型三种类型的瓶刷共聚物的方法,并介绍了合成精确结构的瓶刷聚合物的新进展。     

CO2 permeation properties of poly(ethylene oxide)-based segmented block copolymers

This paper discusses the gas permeation properties of poly(ethylene oxide) (PEO)-based segmented block copolymers containing monodisperse amide segments. These monodisperse segments give rise to a well phase-separated morphology, comprising a continuous PEO phase with dispersed crystallised amide segments. The influence of the polyether phase composition and of the temperature on the permeation properties of various gases (i.e., CO₂, N₂, He, CH₄, O₂ and H₂) as well as on the pure gas selectivities were studied in the temperature range of −5 °C to 75 °C. The CO₂ permeability increased strongly with PEO concentration, and this effect could partly be explained by the dispersed hard segment concentration and partly by the changing chain flexibility. By decreasing the PEO melting temperature the low temperature permeabilities were improved. The gas transport values were dependant on both the dispersed hard segment concentration and the polyether segment length (length between crosslinks). The gas selectivities were dependant on the polyether segment length and thus the chain flexibility.     

紫外光可固化丙烯酸改性聚氨酯(PUA)的ESCA及SEM研究

丙烯酸改性聚氨酯是一类性能优良的紫外光可固化性聚合物。纵观其大量文献报道,多为各种不同用途的专利,而对其物理性能及形态结构方面的基础理论研究却较为薄弱。Wadhwa和Walsh用电子显微镜及动态粘弹谱仪研究了TDI型PUA的微相结构,认为体系为软、硬段均匀混合的均相结构。Cooper等人研究了一系列PUA的动态力学性能,证明其多为两相结构。     

Flexible Gradient Poly(ether-ester) from the Copolymerization of Epoxides and ε-Caprolactone Mediated by a Hetero-bimetallic Complex

Copolymerization is a commonly employed method for optimizing the properties of polymer materials. Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strategy to realize the integration of multiple properties of polyester and polyether, and to develop more high-performance, multi-purpose polymer materials. Herein, the synthesis of poly(ether-ester)s is accessible by employing the biphenyl-linked heterodinuclear salen Cr-Al complex in the presence of PPNCl for the copolymerization of epoxides and ε-caprolactone(CL). Monitoring the copolymerization process reveals that catalyst 1 exhibited good performance for the copolymerization of epoxides and CL, affording copolymers with a gradient sequence structure. The dynamic thermomechanical analysis(DMA) study indicates the obtained poly(ether-ester)s possess enhanced flexibility compared with the block copolymers or blend of PPO and PCL homopolymers with the same ratio. This study provides a theoretical basis for the preparation of high-performance polymer materials.     

微相分离及链结构对聚酯-聚醚嵌段共聚物分子运动的影响

本文首先研究了成型方法和热处理对聚对苯二甲酸乙二酯与聚氧四亚甲基嵌段共聚物动态力学温度谱的影响,结合应力-应变曲线讨论了微相分离与力学性能的关系。其次,比较了三种不同链结构的聚酯-聚醚嵌段共聚物在不同温控程序下的动态力学温度谱,讨论了链结构对软链段结晶的影响。最后观察了聚氨酯-聚醚嵌段共聚物双重玻璃化转变现象并作了解释。     

Synthesis and properties of sulfonated polyurethane ionomers with anions in the polyether soft segments

A series of polyether (PTMO, PEO) polyurethane ionomers having different contents of sodium sulfonate groups in the soft segments have been synthesized. The reaction of transesterification was involved in the incorporation of the sodium sulfonate groups in the polyether. The polyurethane ionomers were characterized by means of dynamic mechanical thermal analysis, differential scanning calorimetry, and small-angle x-ray scattering. Solid-state ionic conductivity was also measured. As the ionization level increased, the compatibility of the hard and soft segments increased and the glass transition region of the soft segment became broader. These samples had relatively higher moduli and good film-forming ability. Moreover, this kind of ionomer provides a very promising ionic conductive multiphase polymer with a single ion transport mechanism. © 1997 John Wiley & Sons, Inc.     

Tetrablock Copolymers Based on Oligoether Diols, 2,4-toluene diisocyanate,Isophorone Diisocyanate,and Methylene-bis-о-chloroaniline

Tetrablock polyurethane ureas with mixed soft segments and dissimilar hard urethane urea blocks, based on oligo(propylene oxide)diol, oligo(tetramethylene oxide)diol, 2,4-toluene diisocyanate, isophorone diisocyanate, and methylene-bis-o-chloroaniline as a low-molecular-mass chain extender were synthesized and studied. The fragmentary ordering of the polymer chains of the new polyurethane urea was proved by rheokinetic data. The structure–property relationship for the polymer was found. The new polyurethane ureas surpass in the true strength the available diblock polyurethane ureas with poly(propylene oxide) soft segments by a factor of 1.5. The strength properties of the new tetrablock polyurethane ureas only weakly depend on the strain rate varied in the range 0.56–0.006 s^–1.