高聚物各种平均相对分子质量的绝对测定——GPC和特性粘数法

从ＧＰＣ数据和特性粘数能较准确迅速求出高聚物的数均、粘均、重均、Ｚ查对分子后进琢相对分子质量与特性粘数关联参数。该方法经聚甲基丙烯酸甲酯验证后，用其表征了聚碳酸亚乙酯（ＰＥＣ）和聚碳酸亚丙酯（ＰＰＣ）。     

高聚物各种平均相对分子质量的绝对测定——GPC和特性粘数法

从GPC数据和特性粘数能较准确迅速求出高聚物的数均、粘均、重均、Z均相对分子质量及相对分子质量与特性粘敷关联参数。该方法经聚甲基丙烯酸甲酯验证后,用其表征了聚碳酸亚乙酯(PEC)和聚碳酸亚丙酯(PPC)。     

二氧化碳共聚物的分子量表征(GPC和特性粘数法)

脂肪族聚碳酸酯的分子量表征问题可以从GPC数据阳特性粘数较迅速可靠地解决,同时求出其数均,粘均,重均,动力学平均分子量,及其分子量—特性粘数关联参数。为此须对以往方法作较大的改进,其关键是用迭代法进行特性粘数(dL/g)与分子量的关联。如此对聚碳酸亚丙酯和碳酸亚乙酯分别得到以下关系: ln(η)=-6.671+0.328ln(?)v+0.0186(ln(?)v)~2 (25℃,THF) (η)=6.64×10~(-5)(?)v~(0.76) (25℃, CHCl_3)     

聚碳酸亚丙酯聚氨酯的合成与性能

用ＣＯ２与环氧丙烷共聚产物聚碳酸亚丙酯制备出聚氨酯（ＰＰＣＰＵ）．同时探讨了ＰＰＣＰＵ最佳合成方法,考察了异氰酸酯基与羟基的比值、扩链交联剂用量等因素对其力学性能的影响．研究了ＰＰＣＰＵ的形态结构及其性能对配比的依赖关系．发现聚碳酸亚丙酯的耐热性因聚氨酯的形成而得到较大的改善,并发现该类材料具有优异的耐水性能．     

聚碳酸亚丙亚乙酯的合成和生物降解

由ＣＯ２和环氧丙烷的催化共聚制备了聚碳酸亚雨酯（ＰＰＣ），向ＰＰＣ引入环氧乙烷结构单元得到聚碳酸亚西亚乙酯（ＰＰＥＣ），用１ＨＮＭＲ等进行了结构表征，并用土埋法进行了生物降解性能的测定，结果表明ＰＰＣ仅在分子量很低时才具备显著的生物降解性能；而ＰＰＥＣ的生物降解速度高于分子量相近的ＰＰＣ．此外，土埋三月后共聚物的组成和分子量都保持基本不变，表明实验条件下生物降解主要在聚合物的表面进行．     

FTIR研究聚碳酸亚丙酯型聚氨酯反应动力学

脂肪族聚碳酸酯型聚氨酯大多是由酯交换或环状碳酸酯开环聚合而得的聚碳酸酯合成的，直接用ＣＯ２共聚物合成聚氨酯弹性体的报道很少。本文采用阴离子配位络合的方法，通过调节聚合，以ＣＯ２与环氧丙烷为单体合成了分子量、官能度可调节的端羟基聚碳酸亚丙酯（ＰＰＣ），...     

聚对苯二甲酸丁二酯/聚对苯二甲酸乙二酯固态缩聚的研究

研究了聚对苯二甲酸丁二酯（ＰＢＴ）／聚对苯二甲酸乙二酯（ＰＥＴ）共混物的固态缩聚反应，从反应动力学过程的测定结果，表明与纯ＰＥＴ或ＰＢＴ不同，其反应速度较快，并呈超加和的相对分子质量（以特性粘数［η］表征）增长。从反应发生在液相的基本观点出发，说明温度、共混等使液相增多，将加速反应的进行，加上共混物之间的相互缩聚和酯交换，生成嵌段共聚物的结果，导致超加和效应。     

CO_2共聚物为基的新型聚氨酯弹性体的合成与性能

本文报道一类以ＣＯ＿２共聚物为基的新型聚碳酸亚丙酯聚氨酯（ＰＰＣＰＵ）弹性体。探讨了这类弹性体的最佳台成方法．讨论了不同配比，不同的扩链交联剂对弹性体的力学性能的影响。研究了弹性体的热性能及耐水性与不同配比的依赖关系。发现控制适当的配比．能获得耐水住能和耐热性能良好的弹性体。     

聚碳酸酯改性聚酯型热塑性聚氨酯弹性体的合成与性能

以聚碳酸１，６－已二醇酯（ＰＣ）、聚己二酸－１，４－丁二醇酯（ＰＢＡＧ）、４，４－二苯基甲烷二异氰酸酯（ＭＤＩ）和１，４－丁二醇（ＢＤＯ）为原料，合成线型聚碳酸酯改性聚酯型热塑性聚氨酯弹性体（ＴＰＣＺＥ）．对其玻璃化转变温度Ｔｇ、力学性能、耐水解性能和流变特性进行了研究。实验结果表明：随ＰＣ二醇含量的增加，弹性体的贮能模量下降，Ｔｇ则向高温方向（从－７．８℃到＋２．６℃）移动。水解后的强度保持率从８５．４％提高到９９，７％和１１７％，熔体的表现粘度降低，加工性能得到改善。     

双流体高聚物配位溶液理论——纯物质的状态方程及其应用

以Ｆｌｏｒｙ局部组合型囚胞理论为雏形，引进空穴数，建立了更符合流体特性的双流体高聚物配位统计模型，以配位分数和局部位分数替代原局部组成中面积接触分数和局部面积接触分数概念，用拟化学近似处理局部配位分数，导出纯物质的状态方程，并应用于聚丙烯（ＰＰ）、聚丁烯－１（ＰＢＴ）、聚苯乙烯（ＰＳ）三个体系的关联，取得了良好的关联精度，根据ＰＰ和ＰＢＴ的链节结构与空穴数的关系，预言了高聚物的链节结构和空穴数与聚     

Thermal,mechanical and rheological properties of biodegradable poly(propylene carbonate) and poly(butylene carbonate) blends

Poly(propylene carbonate)(PPC) was melt blended in a batch mixer with poly(butylene carbonate)(PBC) in an effort to improve the toughness of the PPC without compromising its biodegradability and biocompatibility. DMA results showed that the PPC/PBC blends were an immiscible two-phase system. With the increase in PBC content, the PPC/PBC blends showed decreased tensile strength, however, the elongation at break was increased to 230% for the 50/50 PPC/PBC blend. From the tensile strength experiments, the Pukanszky model gave credit to the modest interfacial adhesion between PPC and PBC, although PPC/PBC was immscible. The impact strength increased significantly which indicated the toughening effects of the PBC on PPC. SEM examination showed that cavitation and shear yielding were the major toughening mechanisms in the blends subjected the impact tests. TGA measurements showed that the thermal stability of PPC decreased with the incorporation of PBC. Rheological investigation demonstrated that the addition of PBC reduced the value of storage modulus, loss modulus and complex viscosity of the PPC/PBC blends to some extent. Moreover, the addition of PBC was found to increase the processability of PPC in extrusion. The introduction of PBC provided an efficient and novel toughened method to extend the application area of PPC.     

Effect of poly(vinyl acetate) (PVAc) on thermal behavior and mechanical properties of poly(3-hydroxybutyrate)/poly(propylene carbonate) (PHB/PPC) blends

To assess the compatibility of blends of synthetic poly(propylene carbonate) (PPC), with a natural bacterial poly(3-hydroxybutyrate) (PHB), a simple casting procedure of blend was used. poly(3-hydroxybutyrate)/poly(propylene carbonate) blends are found to be incompatible according to DSC and DMA analysis. In order to improve the compatibility and mechanical properties of PHB/PPC blends, poly(vinyl acetate) (PVAc) was added as a compatibilizer. The effects of PVAc on the thermal behavior, morphology, and mechanical properties of 70PHB/30PPC blend were investigated. The results show that the melting point and the crystallization temperature of PHB in blends decrease with the increase of PVAc content in blends, the loss factor changes from two separate peaks of 70PHB/30PPC blend to one peak of 70PHB/30PPC/12PVAc blend. It is also found that adding PVAc into 70PHB/30PPC blend can decrease the size of dispersed phase from morphology analysis. The result of tensile properties shows that PVAc can increase the tensile strength and Young’s modulus of 70PHB/30PPC blend, and both the elongation at break and the tensile toughness increase significantly with PVAc added into 70PHB/30PPC.     

Miscibility and isothermal crystallization of poly(L-lactide) and poly(trimethylene carbonate) blends

Miscibility, isothermal crystallization kinetics, and morphology of poly(L-lactide)/poly(trimethylene carbonate)(PLLA/PTMC) crystalline/amorphous blends were studied by differential scanning calorimetry(DSC) and optical microscopy(OM). The heterogeneity of OM images and an unchanged glass transition temperature showed that PLLA was immiscible with PTMC. During isothermal crystallization, the crystallization rate of PLLA improved when the PTMC content was low(≤ 20%). However, when the PTMC content was high(≥ 30%), the crystallization rate decreased significantly. The reason of these nonlinear changes in crystal kinetics was analyzed according to the nucleation and growth process by virtue of a microscope heating stage. The isothermal crystallization morphologies of the blends were also studied by polarized optical microscopy and the results confirmed the conclusions obtained from crystallization kinetics.     

Anti-biofouling by degradation of polymers

Copolymers of methyl methacrylate(MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate) (PEOC) macromonomer(PEOCA) were synthesized,and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation(QCM-D).It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains.Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.     

Synthesis and Properties of Poly(butylene carbonate-co-spirocyclic carbonate)

Poly(butylene carbonateXPBC) has significantly promising applications as a degradable material in the field of polymers, while its poor thermal performance and low crystallization rate are its main defects. To overcome these shortcomings, a series of poly(butylene carbonate-co-spirocyclic carbonateXPBSC) copolymers were synthesized from diphenyl carbonate, 1,4-butanediol and spiroglycol via two-step polycondensation reactions, using magnesium oxide as a catalyst. Differential scanning calorimetry(DSC) results indicated that the glass transition temperature(Tg) values of PBSC copolymers were enhanced from -19℃ to 56℃ with rising the spiroacetal moiety content. Thermogravimetric analysis(TGA) results showed that the resulting PBSCs have a higher thermal stability than that of poly(butylene carbonate). Wide angle X-ray diflraction(WXRD) patterns were characterized to investigate the crystallization behaviour of PBSCs. Tensile testing demonstrated that copolymerization of spiroacetal moieties into PBC chains imparted PBSC with favourable mechanical performance. Typically, PBSC 30 had a tensile modulus of (1735±430) MPa, a tensile strength of (42±5) MPa and an elongation of 504%±36%.     

聚碳酸亚丙酯中环状碳酸酯的IR法测定

用ＩＲ光谱法测定聚碳亚丙酯样品中的环状小分子杂质碳酸亚丙酯。发现该杂质的质量分数与１／（Ａ１１８０／Ａ１２５０＋１）呈现线关系（Ａ１１８０和Ａ１２５０分别为波数１１８０ｃｍ＾－１和１２５０ｃｍ＾－１处的吸光度）；标准偏差为０．０１１；回归系数为０．９９９２。该法用以代替＾ＨＮＭＲ法，可以较简单地给出可靠结果，满足常规测试的要求。     

Improved mechanical property and biocompatibility of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) for blood vessel tissue engineering by blending with poly(propylene carbonate)

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(propylene carbonate) (PPC) were blended by solvent casting method into films at various weight ratios in order to obtain materials with properties more suitable for blood vessel tissue engineering than pure PHBHHx alone. FTIR and XRD analysis indicated the crystal structure of PHBHHx was not altered but the crystallinity was reduced by the interfusion of PPC. Mechanical properties of the films were improved significantly by blending with PPC. A lower elastic modulus and a higher elongation at break were obtained with the increase of PPC content. Wettability, fibronectin adsorption and adhesion of rabbit aorta smooth muscle cells (RaSMCs) on blend films were similar to or better than that on PHBHHx film. All these results showed promises of PHBHHx/PPC blended materials as scaffold material for blood vessel tissue engineering.     

Studies of the hydrolytic stability of poly(urethane-urea) elastomers synthesized from oligocarbonate diols

Polyurethane and poly(urethane-urea) elastomers synthesized from oligocarbonate diols are characterized by very good mechanical properties, biocompatibility and excellent resistance to both oxidation and hydrolysis and therefore are widely used in medical applications. In this paper the results of studies on hydrolytic stability of poly(urethane-urea) elastomers (PURC) obtained by moisture-curing of corresponding urethane prepolymers synthesized from isophorone diisocyanate (IPDI) and four different oligocarbonate diols (OCD) are presented. OCD were synthesized from dimethyl carbonate and 1,6-hexanediol, from cyclic ethylene carbonate and 1,6-hexanediol as well as from trimethylene carbonate. The changes of the sample weight, mechanical properties and surface properties after immersion in a standard phosphate buffer solution (pH = 7.4) for up to 3 months at 70 °C were monitored. It was shown that neither sample weight nor mechanical properties changed significantly for PURC obtained from OCDs synthesized from 1,6-hexanediol and dimethyl carbonate or ethylene carbonate what confirms good resistance to hydrolysis of those PURC. Also SEM studies of those samples before and after immersion did not reveal any surface degradation effects. However, PURC sample obtained from OCD synthesized from trimethylene carbonate showed significant changes in mechanical properties and distinct change of appearance and surface erosion after 3 months immersion. The initial decrease and later increase of stress at break observed for PURC samples during immersion, was explained by the reaction of residual NCO groups present in PURC with water leading to molecular weight increase which proceeded during immersion period in parallel to hydrolysis of carbonate bond.     

立构复合PL(D) LA-TMC无规共聚物的制备、结构与性能

以辛酸亚锡为催化剂,通过开环聚合法制备了聚左旋乳酸-三亚甲基碳酸酯(PLLA-TMC)和聚右旋乳酸-三亚甲基碳酸酯(PDLA-TMC)无规共聚物.利用共聚物中PLLA/PDLA链段形成立构复合体,通过溶液浇注法制备了PLLA-TMC/PDLA-TMC立构复合聚乳酸材料(sc-PLA-TMC).研究结果表明,聚合物链中的柔性TMC单元可以增强L(D)LA链段的运动能力,有助于不同旋光性的LA链段形成立构复合晶体,但也使得L(D)LA链段的规整度和序列长度降低.即随着共聚物链段中柔性TMC单元摩尔含量的增加,sc-PLA-TMC中同质结晶能力降低.当TMC含量≥5%时,仅生成熔点200℃的PLLA/PDLA立构复合结晶,表明sc-PLA-TMC的耐热性有所提高.蛋白酶K降解实验表明,PL(D)LA-TMC共聚物的降解速率不但比PLLA高,而且可通过共聚物中TMC含量进行调控.     

聚碳酸乙烯撑酯与双端氨基聚乙二醇交联体系固定化酶载体的合成与表征

将聚碳酸乙烯撑酯(PVCA)与α,ω-双端氨基聚乙二醇(H₂N-PEG-NH₂)溶于DMF,于液蜡中进行交联反应制得亲水性固定化酶载体,将其与胰蛋白酶进行偶联反应制备了固定化胰蛋白酶.酶蛋白的比活力及其于载体上的结合量与反应条件有关,当w(PVCA)/w(H₂N-PEG-NH₂)为0.5时,二者均处于最高值.此固定化酶酶促反应的最适pH值和Km值均较之溶液酶有显著提高,但二者的最适酶促反应温度却相当一致.