N-炔丙基酰胺共聚物组成对其光学活性的影响

通过与手性单体共聚,可调控基于非手性单体所制备的螺旋聚合物的光学活性。文中利用[Rh]金属有机催化剂,进行了手性(M1)和非手性(M2)N-炔丙基酰胺单体的共聚反应,聚合物产率高于97%。利用圆二色光谱技术及旋光仪对共聚物的光学活性进行了表征,发现共聚物组成对其光学活性有显著影响,不仅影响共聚物光学活性的大小,甚至还决定着聚合物主链所形成螺旋结构的手性。     

开环易位聚合-加氢法制备侧链功能化聚烯烃

以1,5-环辛二烯为起始原料,通过一系列反应制备了功能性单体5-溴代丙酸酯基-环辛烯(M1)。采用Grubbs II代催化剂(G2)对单体M1进行开环易位聚合反应(ROMP)制备了均聚物P1。调整M1与环辛烯的单体投料比,通过开环易位共聚反应制备了一系列无规共聚物P5%、P10%、P15%和P20%;共聚物中功能性单体M1的含量与单体配比接近,且无规共聚物的相对分子质量分布比均聚物要窄。对不饱和聚合物进行化学加氢反应,制备了饱和的功能化聚烯烃。热分析结果表明,随着功能单体M1投料比例的增加,无规共聚物的熔点呈现下降趋势;加氢后的饱和聚合物HP1的玻璃化转变温度比不饱和聚合物P1提高了40℃;加氢后饱和聚合物的热稳定性提高。     

甲基丙烯酸甲酯与丙烯酸丁酯规整接枝共聚物的合成及性能研究

采用聚丙烯酸丁酯大分子单体和甲基丙烯酸甲酯小分子单体共聚 ,合成了以甲基丙酸甲酯为主链、丙烯酸丁酯为支链的规整接枝共聚物。用红外光谱表征结构 ,研究了大单体的投料量、引发剂的用量及共聚反应温度对接枝效率的影响。并且研究了接枝共聚物的力学性能影响因素 ,当聚丙烯酸丁酯大单体的分子量大于 50 0 0 ,投料重量百分比在 6 0 %左右 ,得到性能良好的热塑性弹性体     

异丁烯醇聚氧乙烯醚与丙烯酸的竞聚率及共聚物链段分布EI北大核心CSCD

以过硫酸铵(APS)为引发剂,在50℃对异丁烯醇聚氧乙烯醚(HPEG)大单体与丙烯酸(AA)进行低转化率(<15%)的水溶液共聚反应。用凝胶渗透色谱和高效液相色谱分别测定反应体系中HPEG和AA剩余量。依据设计反应单体投料比,K-T作图法处理数据,得到异丁烯醇聚氧乙烯醚(HPEG)与丙烯酸(AA)的竞聚率分别为:r1(HPEG)=0.017,r2(AA)=1.70。进而分析了HPEG与AA共聚物P(HPEG-co-AA)的链段微结构和链节分布。当投料比为1∶4时,二元共聚物P(HPEG-co-AA)中HPEG以1个单体单元存在。丙烯酸均聚形成的链段以3~15个单体单元的链段长度为主,链段数均长度为7.8。     

异丁烯醇聚氧乙烯醚与丙烯酸的竞聚率及共聚物链段分布

以过硫酸铵(APS)为引发剂,在50℃对异丁烯醇聚氧乙烯醚(HPEG)大单体与丙烯酸(AA)进行低转化率(15%)的水溶液共聚反应。用凝胶渗透色谱和高效液相色谱分别测定反应体系中HPEG和AA剩余量。依据设计反应单体投料比,K-T作图法处理数据,得到异丁烯醇聚氧乙烯醚(HPEG)与丙烯酸(AA)的竞聚率分别为:r1(HPEG)=0.017,r2(AA)=1.70。进而分析了HPEG与AA共聚物P(HPEG-co-AA)的链段微结构和链节分布。当投料比为1∶4时,二元共聚物P(HPEG-co-AA)中HPEG以1个单体单元存在。丙烯酸均聚形成的链段以3~15个单体单元的链段长度为主,链段数均长度为7.8。     

对二氧环己酮与丙交酯共聚反应的~1H-NMR分析

由对二氧环己酮（PDO）和丙交酯（LA）单体,在不同温度下合成了PDO-co-LA共聚物,采用核磁共振（1H-NMR）研究了共聚反应动力学和共聚物分子链结构,提出了一种链段平均序列长度的计算方法。结果显示,丙交酯在共聚反应中的聚合能力要比对二氧环己酮强;实验条件下LA/PDO投料物质的量比为2/3时,共聚物中PDO与L...     

超声波辐照作用下部分水解聚丙烯酰胺与甲基丙烯酸酯共聚反应的研究

研究了部分水解聚丙烯酰胺（ＨＰＡＭ）和一系列甲基丙烯酸酯在超声波辐照作用下的共聚反应。研究结果表明，共聚反应前期，单体的转化率随单体水溶性增大而增大，共聚反应动力学决定于单体的水溶性。通过红外光谱、核磁共振及质谱研究了共聚物的结构．证实共聚物为嵌段体。     

PPO/PA6纳米共混物的制备及结构表征

采用一种新的制备PPO／PA6共混物的方法，从己内酰胺（CL）单体出发，在聚苯醚（PPO）存在下阴离子开环聚合己内酰胺，由于其中一部分PPO主链上接枝了活性苯酯基团，能促进PA6链在其上增长，从而同时形成了PA6均聚物与PPO—g—PA6接枝共聚物，实现了原位聚合与原住增容的同步实施，并用SEM对其微观相形态结构进行了研究，控制共混条件可制备PA6纳米分散的PPO／PA6共混物。     

超声波辐照作用下部分水解聚丙烯酰胺与甲基丙烯酸酯共…

研究了部分水解聚丙烯酰胺（ＨＰＡＭ）和一系列甲基丙烯酸酯在超声波辐照作用下的共聚反应。研究结果表明，共聚反应前期，单体的转化率随单体水溶性增大而增大，共聚反应动力学决定于单体的水溶性。通过红外光谱、核磁共振及质谱研究了共聚物的结构，证实共聚物为嵌段体。     

聚L-丙氨酸-聚乙二醇嵌段共聚物溶液的二级结构

分别以氨基聚乙二醇(PEG-NH2)和氨基聚乙二醇单甲醚(M PEG-NH2)为大分子引发剂,制备了三嵌段(ABA)和两嵌段(AB)的聚L-丙氨酸-聚乙二醇嵌段共聚物;利用圆二色光谱(CD)研究了共聚物在溶液中的二级结构及其影响因素。结果表明,在水溶液中嵌段共聚物主链主要以α-螺旋构象存在;在一定范围内,α-螺旋含量随共聚物溶液浓度的增大而增大,随溶液离子强度的增大而降低;相同条件下,AB型共聚物在溶液中的α-螺旋含量比ABA型共聚物高。     

Chiral Nanostructures from Helical Copolymer–Metal Complexes: Tunable Cation–π Interactions and Sergeants and Soldiers Effect

Poly(phenylacetylene) (PPA) copolymers containing (R)‐ or (S)‐MPA as minor chiral pendant can be forced to selectively adopt the right‐ o left‐handed helix, in the presence of small amounts of Na⁺ or Ag⁺ (“Sergeants and Soldiers Effect”) by addition of a donor cosolvent. The helical sense depends exclusively on the chiral monomer/donor cosolvent ratio, and this allows a perfect on/off tuning of the helicity of the copolymer. When the amount of the donor cosolvent is low, the metal ion complex is stabilized by a cation–π interaction, which is selectively cleaved when the amount of cosolvent is higher. Macroscopically chiral nanospheres and nanotubes composed by helical copolymers with P or M helical sense are also described. Our results demonstrate that it is possible to obtain the two enantiomeric helical structures (P and M helicities) and the corresponding nanospheres and nanotubes from a single helical copolymer, by controlled activation/deactivation of the Sergeant and Soldiers Effect with a donor cosolvent.     

Fabrication of hydrophilic paclitaxel-loaded PLA-PEG-PLA microparticles via SEDS process

In this work, chemically bonded poly(D, L-lactide)-polyethylene glycol-poly(D, L-lactide) (PLA-PEG-PLA) triblock copolymers with various PEG contents and PLA homopolymer were synthesized via melt polymerization, and were confirmed by FTIR and ¹H-NMR results. The molecular weight and polydispersity of the synthesized PLA and PLA-PEG-PLA copolymers were investigated by gel permeation chromatography. Hydrophilicity of the copolymers was identified by contact angle measurement. PLA-PEG-PLA and PLA microparticles loaded with and without PTX were then produced via solution enhanced dispersion by supercritical CO₂ (SEDS) process. The effect of the PEG content on the particle size distribution, morphology, drug load, and encapsulation efficiency of the fabricated microparticles was also studied. Results indicate that PLA and PLA-PEG-PLA microparticles all exhibit sphere-like shape with smooth surface, when PEG content is relatively low. The produced microparticles have narrow particle size distributions and small particle sizes. The drug load and encapsulation efficiency of the produced microparticles decreases with higher PEG content in the copolymer matrix. Moreover, high hydrophilicity is found when PEG is chemically attached to originally hydrophobic PLA, providing the produced drug-loaded microparticles with high hydrophilicity, biocompatibility, and prolonged circulation time, which are considered of vital importance for vessel-circulating drug delivery system.     

添加正十八烷微胶囊的丙烯腈与甲基丙烯酸甲酯共聚物的合成与表征

采用氧化还原引发剂合成了含有正十八烷微胶囊的丙烯腈/甲基丙烯酸甲酯共聚物。测试表明,丙烯腈和甲基丙烯酸甲酯单体发生了共聚,共聚物中丙烯腈成分的实测含量略低于理论含量;试样中的微胶囊的吸热和放热温度与纯微胶囊的吸热放热温度接近,随着微胶囊含量的增加,共聚物中微胶囊的热效率逐渐增大;随着微胶囊含量的增加,试样中共聚物的结晶度增大。     

9,9-二(丙酸二甲氨基乙酯)芴共聚物的合成及荧光性能

采用迈克尔加成反应制备了单体2,7-二溴-9,9-二(丙酸二甲氨基乙酯)芴(FDMAEA);采用Suzuki偶合反应制备了不同FDMAEA结构单元含量的醇溶性9,9-二(丙酸二甲氨基乙酯)芴-9,9-二辛基芴共聚物(PFDMAEA)。通过核磁共振、凝胶渗透色谱、溶解性测试、紫外-可见光光谱、荧光发射光谱等对其进行了分析研究。结果表明,成功合成了2,7-二溴-9,9-二(丙酸二甲氨基乙酯)芴及9,9-二(丙酸二甲氨基乙酯)芴-9,9-二辛基芴共聚物。该共聚物在极性溶剂,如甲醇中具有良好的溶解性。由于含有DMAEA支链的PFDMAEA主链容易扭曲,共轭长度变短,共聚物的紫外吸收光谱和荧光光谱随着FDMAEA含量的增加而发生蓝移。荧光发光光谱研究表明,溶剂的极性、溶液的浓度、温度和pH值对共聚物的发光性能有很大的影响。随着溶剂极性增大,共聚物的荧光发射强度不断增加。荧光发射强度随溶液浓度的增加先增加后降低,随着溶液温度的上升而降低。当溶液pH值由1增大到14时,荧光强度不断降低,直至淬灭。     

Synthesis and characterization of MeO–PEG–PLGA–PEG–OMe copolymers as drug carriers and their degradation behavior in vitro

The objective of this study was to characterize the methylpoly (ethylene glycol)-poly (lacticacid-co-glycolicacid)-poly (ethylene-glycol) (MeO-PEG-PLGA-PEG-OMe, abbreviation as PELGE) copolymers as intravenous injection drug delivery carriers and their degradation behavior in vitro. A series of MeO-PEG-PLGA-PEG-OMe copolymers with various molar ratios of lactic to glycolic acid and various molecular weights and different MeO-PEG contents were synthesized by ring-opening polymerization in the presence of MeO-PEG with molar masses of 2000 and 5000, using stannous octoate as the catalyst. The hydrophilicity of PELGE copolymers, evaluated by contact angle measurements, was found to increase with an increase in their MeO-PEG contents. Methylpoly (ethylene glycol)-poly (lacticacid-co-glycolicacid) (MeO-PEG-PLGA, abbreviation as PELGA) nanoparticles and PELGE nanoparticles were prepared using the emulsion-solvent evaporation technique (o/w) with Pluronic F68 (Poloxamer 188 NF) as emulsifier in the external aqueous phase. The degradation behavior of the nanoparticles was evaluated by the lactate generation with time upon their in vitro incubation in PBS (pH 7.4). The rate of in vitro degradation of the PELGE or PELGA nanoparticles depended on their composition, increasing with an increase in the proportion of MeO-PEG or LA in the copolymer chains. The degradation rate was slower at higher lactide: glycolide ratio. The lower the molecular weight of PELGE; the higher the degradation rate of the nanoparticles.     

Design of low temperature self-cured phthalonitrile-based polymers for advanced glass fiber composite laminates

Self-promoted copolymerization behavior and processability of phthalonitrile oligomer/phthalonitrile containing benzoxazine (Po/BA-ph) system were investigated by differential scanning calorimetry and dynamic rheological analysis. The results revealed that Po/BA-ph systems exhibited double-stage curing behaviors which corresponded to the ring-opening polymerization of benzoxazine rings and ring-formation polymerization of nitrile groups. Compared with Po, processability of Po/BA-ph blends was improved and could be tuned by varying BA-ph contents, processing temperature, and time. The structures of the copolymers were also characterized and discussed to further confirm the copolymerizing behaviors. Then Po/BA-ph copolymers were employed to prepare Po/BA-ph/glass fiber (GF) composite laminates, and their mechanical and thermal properties were investigated. Compared with those of Po/GF composites, the flexural strength and modulus of Po/BA-ph/GF composites were increased by 6.5 and 25 %, respectively. All of the Po/BA-ph/GF composite laminates were stable up to 430 °C in air. The systematic study of Po/BA-ph system could enrich the thermosetting resin/thermosetting resin systems in industrial applications. Meanwhile, the outstanding mechanical properties and thermal stabilities enable the Po/BA-ph/GF composite laminates to be further applied in the areas which require excellent mechanical properties and high temperature resistance.     

Compositional study and cytotoxicity of biodegradable poly(ester urethane)s consisting of poly[(R)-3-hydroxybutyrate] and poly(ethylene glycol)

Biodegradable PHB–PEG multi-block polyurethane copolymers comprising PHB blocks (M_n: 1100, 1740 and 3240) and PEG blocks (M_n: 1960, 3250, 4150 or 7950) were synthesized followed by characterization by GPC, ¹H NMR, and FT-IR. The PHB contents ranged from 9 to 62% by weight. The copolymers displayed improved thermal stabilities compared with their respective precursors. The morphological structures of the copolymers were studied by FT-IR, DSC and XRD. FT-IR revealed the existence of amorphous and crystalline phases of PHB. Both DSC and XRD analyses showed that separate crystalline phases are formed by PEG and PHB blocks in the copolymers. Upon annealing, the melting transition temperature (T_m), melting enthalpy (ΔH_m) and the fractional crystallinity (X_c) of the PEG block increased when the length of PEG incorporated into the copolymer increased. These values were higher when the PHB block length is shorter as the shorter PHB chain does not disrupt the crystallization of PEG as much as the longer PHB chain. A similar disruptive effect on the crystallization of PHB segments was observed by varying PEG chain lengths but the effect is less pronounced compared with the PEG segments. A comparison of the swelling properties of the poly(ester urethane)s showed that the length and crystalline properties of the PHB block significantly affects the water uptake properties of the copolymers. The crystalline properties and the water uptake capacities of the copolymers could be fine-tuned by consideration of the length of the PHB and PEG block incorporated. The results of the cytotoxicity tests demonstrated that the poly(PHB/PEG) urethanes were non-cytotoxic and could potentially be used for biomedical purposes.     

Effect of norbornene content on laser ablation of cyclic olefin copolymers

The ablation of cyclic olefin copolymers (COC) by 5 ns/248 nm laser has been examined as a function of norbornene content (61–82 wt.%). The dependence of ablation rate on laser fluence, repetition rate and pulse number has been determined over the range of composition of the copolymers. The ablation rate has increased logarithmically with laser fluence in accordance with the Beer–Lambert relationship. An increase in norbornene content has resulted in an increase in ablation rate and a decrease in threshold fluence. These trends have been attributed to a higher intramolecular rigidity of the chain structure in COC with increasing norbornene content. The morphology of the ablated surfaces was characterised by the formation of voids at high norbornene contents.     

Evaluation of copolymers of polyethylene oxide and polybutylene terephthalate (polyactive): mechanical behaviour

Polyether–polyester segmented block copolymers (Polyactive®) on the basis of polybutylene terephthalate (PBT) and polyethylene oxide (PEO) were mechanically tested. Tensile strength and modulus of elasticity in compressive and tensile deformation were recorded according to ASTM standards. These tests were done in vitro under dry and wet conditions, and after 3, 9 and 25 wk subcutaneous implantation of these materials in goats. Strength and modulus of elasticity were higher with increased contents of PBT in the copolymers. After water uptake, the polymer displayed a lower strength and stiffness. Disintegration of the materials with 70% PEO content and dumb-bell shape was noted at 3 wk. Disintegration of the cylinders of the same material was seen after 25 wk implantation. Of the materials with 60% PEO content, only four of the five dumb-bells had disintegrated after 25 wk implantation. The in vivo test results of all other implants did not show a clinically relevant decrease of strength and stiffness with time after implantation of the copolymers in the goats. Mechanical behavior of the various copolymers seemed mainly determined by the amount and integrity of the PBT phase.     

液晶基元直接横挂于主链上的液晶共聚物的合成与研究

以含液晶基元的单体２，５－双（４－甲氧基苯甲酰氧基）苯乙与苯乙烯通过自由基共聚合反应，首次合成了一系列含液晶性和非液晶性两种序列结构的共聚物。采用ＤＳＣ、偏光显微镜和Ｘ衍射方法研究了共聚物的液晶行为，发现单体和共聚物（只有ＣＰ－５和ＣＰ－６）有很好的热致液晶性。随共聚物中介晶单体单元含量的增加，共聚物玻璃化转变温度Ｔ和热分解温度Ｔ呈规律变化。