PBS及其共聚酯生物降解性能的研究进展

综述了PBS(聚丁二酸丁二醇酯)、PBS基脂肪族共聚酯,PBS基芳香族共聚酯的结构和生物降解性能,并分别总结了它们的结构和生物降解性能之间的关系.PBS基脂肪族共聚酯分为线型PBS基脂肪族共聚酯和枝状PBS基脂肪族共聚酯,分别对它们进行了介绍.得出了PBS及其共聚酯的结构、分子量、聚酯形态、熔点、结晶度等与共聚酯的生物降解性之间的关系.     

线性PBS基脂肪族聚酯的合成和降解研究

为了探讨线性PBS基脂肪族共聚酯的结构和降解之间的关系,首先合成了线性PBS基脂肪族共聚酯,即聚丁二酸丁二醇酯-共-聚己二酸丁二醇酯P(BS-co-BA),聚丁二酸丁二醇酯-共-癸二酸丁二醇酯P(BS-co-BSe),并将线性PBS基脂肪族共聚酯及PBS在土壤悬浮液中进行降解,通过GPC、熔点测定仪对线性PBS基脂肪族共聚酯的分子量和熔点进行了测定;通过测定降解过程中失重率和降解前后聚酯薄膜表面形貌来对共聚酯降解程度进行表征。结果表明:随着二元酸碳链的增长,分子对称性降低,降解性能增大。通过观察分子量,熔点及降解失重率的测定结果,得出分子量越大,降解越不容易进行;熔点越小,降解性能越好。     

新型车用材料聚（丁二酸-co-己二酸丁二醇）共聚酯酶促降解性能研究

通过酯化和缩聚反应制备聚丁二酸丁二醇酯（PBS）、聚己二酸丁二醇酯（PBA）和聚（丁二酸-co-己二酸丁二醇）共聚酯（P(BS-co-BA)）,对PBS、PBA和P(BS-co-BA)进行酶促降解研究。结果表明：与PBS和PBA相比,共聚酯具有良好的生物降解性能。6种聚酯酶水解速率依次为P(BS-co-40%BA)>P(BS-co-60%BA)>P(BS-co-80%BA)>P(BS-co-20%BA)>PBA>PBS。P(BS-co-40%BA)在10 h内基本完全降解,比PBS快26 h。与PBA相比,共聚酯的热稳定性得到提高,P(BS-co-40%BA)热分解50%的温度比PBA高22.3℃。随着降解时间的增加,共聚酯的化学结构、晶体结构和热稳定性基本不变,有利于其在新能源汽车设计中的应用。     

聚丙交酯及可降解脂肪族聚酯类纤维的结构与生物降解性能

以聚丙交酯为代表讨论了可生物降解聚酯类纤维的结构特征与生物降解性能,对聚酯类纤维生物降解的机理、影响因素进行分析,指出聚合物的分子质量及分子链结构、聚集态结构、环境的温度、湿度、pH值及酶种类等因素对其降解性能有明显的影响,合理控制这些因素,可对其降解速度实现人为控制,以适应不同用途的需要.     

1,2-环己二醇改性聚丁二酸丁二酯的结构与性能

以1,4-丁二酸(SA)、1,4-丁二醇(BDO)、1,2-环己二醇(CHD)为原料,通过改变BDO与CHD投料比,采用熔融缩聚法制备了一系列的CHD改性聚丁二酸丁二醇酯(PBS)共聚酯。采用¹H-NMR表征了共聚酯的化学结构,并且,分析了CHD占主链二醇含量对共聚物分子量及其分子量分布、熔融和结晶性能、热稳定性能、拉伸性能及脂肪酶降解性能的影响。结果表明,随着CHD含量的增加,共聚酯的数均分子量从7.45×10⁴下降至4.75×10⁴,由结晶度48.5%的半晶态转变为无定形态,热分解损失为质量5%时,温度降低了26.7℃,拉伸强度由38.2 MPa降低至14.9 MPa,但脂肪酶降解性能显著提高。PBS主链引入适量CHD后,可以有效地调控PBS的结晶度及柔顺性,提高了PBS在非堆肥条件下的降解速度。     

酶催化一步法制备高分子质量PBSA共聚酯及其性能

聚丁二酸丁二醇酯(PBS)是一种具有广阔发展前景的生物基聚酯品种,但由于其分子链段柔性较高并且结晶度高,在实际应用过程中仍然面临热性能、力学性能、降解性能不足的弊端。选用条件更为温和的酶催化体系,以丁二酸二乙酯、己二酸二乙酯、丁二醇为原料,Novozym-435(固定化CALB酶)为催化剂,甲苯为溶剂,合成制备了一系列高分子质量的聚(丁二酸丁二醇-co-己二酸丁二醇)(PBSA)三元共聚酯。在反应温度80℃、酶的质量分数为10%的条件下,所制备的PBS与PBSA共聚酯的数均分子质量在18 400～21 200 g/mol,多分散性指数在1.7～2.0之间。采用核磁共振谱仪对制备的共聚酯产物的化学结构进行了表征。TGA结果表明,酶催化体系下的PBSA共聚酯的热稳定性要高于熔融体系下的产物。DSC与WAXD的结果表明,引入己二酸链段后,PBS的结晶能力下降。酶催化反应避免了重金属催化剂的使用,进一步拓宽了PBS在生物医药领域范围的潜在应用。     

聚丁二酸丁二醇酯基脂肪族聚酯生物降解研究进展

介绍了聚丁二酸丁二醇酯（PBS）基聚酯的生物降解研究及相关影响因素,分别从微生物降解,生理环境降解,酶降解三方面进行总结,并对聚丁二酸丁二醇酯（PBS）基聚酯降解的研究方向及应用前景进行了展望。     

金属离子对脂肪族聚酯降解性能的影响

在土壤培养液中添加不同种类的金属离子,研究了它们对可生物降解聚酯聚乳酸（PLA）、聚丁二酸丁二酯（PBS）膜降解性能的影响。采用傅里叶变换红外光谱仪表征了PLA和PBS膜降解前后的化学结构。结果表明：所有降解后的膜表面均有明显被侵蚀的痕迹;在土壤培养液中的Mg^2＋,Zn^2＋,Ca^2＋对PLA的降解性能有促进作用,对PBS的降解性能则影响不大;降解后PLA膜的玻璃化转变温度有所升高,但PBS膜变化不大。     

不同主链PBS基共聚酯的酶催化降解及分子模拟

采用多种二醇改性聚丁二酸丁二醇酯(PBS),合成了碳链长度不同的PBS基共聚酯。在CHCl3中,以固定化南极假丝酵母脂肪酶b(N435)降解各共聚酯,研究了碳链长度对共聚酯降解速率和降解率的影响。通过共聚酯分子量、降解产物及热稳定性变化,分析了影响降解效果的因素。采用分子对接技术解释了脂肪酶与底物之间的相互作用机理。结果表明:随共聚酯碳链增长,共聚酯降解效果逐步提升,己二醇改性时的降解速率最高,降解率可达80%;共聚酯分子链越长,产生的低聚物越多;随分子链增长,共聚酯热稳定性逐步下降。分子对接显示:脂肪酶催化三联体、活性口袋残基及底物三者之间形成的氢键对酶的催化作用至关重要。     

可生物降解聚酯的结构与性能

以聚丙交酯为代表讨论了可生物降解聚酯纤维的结构特征与生物降解性能，对聚酯类纤维生物降解的机理，影响因素进行分析，指出聚合物的分子质量及分子链结构、聚集态结构、环境的温度，湿度，ｐＨ值及酶种类等因素对其降解性能有明显的影响，合理控制这些因素，可对其降解速度实现人为控制，以适应不同用途的需要。     

Preparation,characterization and degradation characteristics of polyanhydrides containing poly(ethylene glycol)

Poly(ethylene glycol) (PEG) segments were introduced into a polyanhydride main chain by copolymerization of terminal-carboxylated poly(ethylene glycol) with diacidic monomers (sebacic acid and trimellitylimidoglycine). IR and ¹H NMR spectroscopy confirmed the copolymer structures. DSC analysis showed that these polyanhydrides have low T_g and low crystallinity. In vitro degradation tests indicated that introducing PEG segments accelerated the degradation rate of these polymers and the degradation duration could be manipulated from 3 days to 3 weeks. The pH of the environment caused by the polymer degradation was lower than 5.0; therefore, the polyanhydrides could be used as components of a newly designed pulsed-release device for peptide and protein delivery. © 1999 Society of Chemical Industry     

聚氨酯纯硬段模拟化合物的研究

用乙二醇、1,4-丁二醇、三缩四乙二醇和甲苯二异氰酸酯为原料 ,以二正丁胺为封端剂合成了几种不同结构的聚氨酯纯硬段模拟化合物。并用FT -IR、DSC、TG、WAXD对化合物的结构进行了研究。结果表明 ,化合物有结晶 ,纯硬段模拟化合物的降解温度与二醇的结构无关。     

Synthesis and characterization of biodegradable aliphatic copolyesters with poly(tetramethylene oxide) soft segments

A series of aliphatic poly(ether–ester)s based on flexible poly(tetramethylene oxide) (PTMO) and hard poly (butylene succinate) (PBS) segments were synthesized by the catalyzed two‐step transesterification reaction of dimethyl succinate, 1,4‐butanediol, and α,ω‐hydroxy‐terminated PTMO (M_n = 1000 g/mol) in the bulk. The content of soft PTMO segments in the polymer chains was varied from 10 to 50 mass %. The effect of the introduction of the soft segments on the structure, thermal, and physical properties, as well as on the biodegradation properties was investigated. The composition and structure of the aliphatic segmented copolyesters were determined by ¹H NMR spectroscopy. The molecular weights of the polyesters were verified by viscometry of dilute solutions and polymer melts. The thermal properties were investigated using DSC. The degree of crystallinity was determined by means of DSC and WAXS. Biodegradation of the synthesized copolyesters, estimated in enzymatic degradation tests on polymer films in phosphate buffer solution with Candida rugosa lipase at 37°C, was compared with hydrolytic degradation in the buffer solution. Viscosity measurements confirmed that there was no change in molecular weight of the copolyesters leading to the conclusion that the degradation mechanism of poly(ester–ether)s based on PTMO segments occurs through the surface erosion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Morphology and biodegradation of microspheres of polyester–polyether block copolymer based on polycaprolactone/polylactide/poly(ethylene oxide)

Porous microspheres of polyester–polyether block copolymer based on polycaprolactone/polylactide/poly(ethylene oxide) (PCEL) were prepared by an emulsification–solvent evaporation technique. The effect of hydrophilicity/hydrophobicity of the polymer on the morphology of the PCEL microspheres was studied and compared with that of polycaprolactone (PCL) and polycaprolactone/poly(ethylene oxide) block copolymer (PCE) microspheres. It was demonstrated by X‐ray photoelectron spectroscopy (XPS) that the enrichment of PEO segments on the surface of the microspheres occurred during solvent evaporation of the microdrops and lead to porous structure of the microspheres. The effects of the content and length of PEO segments of the PCEL polymer on the morphology of the microspheres were studied. The degradation behaviour of film‐like and microsphere‐like PCEL was investigated at pH 7.4 and 37 ± 1 °C. The shape of the PCEL samples had no obvious effect on the degradation rate of the material and homogeneous degradation was a main process. The degradation rate of PCEL microspheres was enhanced in the presence of the enzyme lipase. ¹H NMR measurements revealed that the PEO content reduced with degradation time because the PEO segment was broken down and dissolved in the medium during degradation. © 2000 Society of Chemical Industry     

Biodegradable aliphatic/aromatic copoly(ester-ether)s: the effect of poly(ethylene glycol) on physical properties and degradation behavior

A series of high molecular weight copolymers based on poly(L-lactic acid) (PLLA) as the biodegradable aliphatic segments, poly(butylene terephthalate) (PBT) as the rigid aromatic segments and hydrophilic poly(ethylene glycol) (PEG) as the soft segments were synthesized with the aim of developing novel polymer materials which could combine high physical properties with good biodegradability. Via direct melt polycondensation of terephthalic acid (TPA), 1,4-butanediol (BDO), poly(L-lactic acid) oligomer (OLLA) and PEG, biodegradable aliphatic/aromatic copoly(ester-ether)s, poly(butylene terephthalate-co-lactate-co-ethylene glycol) (PBTLG), were prepared. The effect of the introduction of PEG soft segments on the synthesis, mechanical properties and thermal stabilities as well as the degradation behaviors of the final copolymers was investigated. When the PEG units were incorporated into the polymer main-chains, the weight-average molecular weight of the copolymers increased from 53,700 g/mol to 177,000 g/mol and the tensile strength (σ) improved by nearly two times from 6.5 MPa to 12.8 MPa for PBTLG1000-0.5. The glass-transition temperature (T _g) gradually decreased from 26.9 °C down to −5.5 °C and a depression of melting temperature was observed with the increase of PEG content. According to the in vitro hydrolytic degradation observation, all of the copolymers underwent significant degradation in phosphate buffer solution at 37 °C and the water absorption as well as the degradation rate of PBTLGs displayed a strong dependency on the PEG content.     

Synthesis and characterization of biodegradable polyurethanes with unsaturated carbon bonds based on poly(propylene fumarate)

The segmented polyurethanes synthesized from biodegradable polyesters are very promising and widely applicable because of their excellent physiochemical properties. Poly(propylene fumarate) (PPF), a kind of linear aliphatic unsaturated and biodegradable polyesters, has been well recognized in biomedical applications. Herein novel polyurethanes (PPFUs) were synthesized based on the PPF‐diol, diisocyanates such as 1,6‐diisocyanatohexane, l ‐lysine diisocyanate, and dicyclohexylmethane diisocyanate, and chain extenders such as 1,4‐butylene glycol and l ‐lysine methyl ester hydrochloride (Lys‐OMe·2HCl). By varying the types of diisocyanates, and chain extenders, and the proportion of hard segments, the PPFUs with tailored properties such as mechanical strength and degradation rate were easily obtained. The synthesized PPFUs had an amorphous structure and slight phase separation with strong hydrogen bonding between the soft segments and the hard segments. The elongation of PPFU elastomers reached over 400% with a slow deformation‐recovery ability. The PPFUs were more sensitive to alkaline (5 M, NaOH) hydrolysis than acid (2 M, HCl) and oxidative (30 vol.%, H₂O₂) erosion. The tensile strength, deformation‐recovery ability, and glass transition temperature of the PPFUs were improved with the increase of hard segment proportion, while the degradation rate was opposite because of the faster degradation of the soft segments. In vitro culture of smooth muscle cells in the extractant of the PPFUs or on the PPFUs film surface revealed low cytotoxicity and good cytocompatibility in terms of cell viability, adhesion, and proliferation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42065.     

Mechanism of degradation and crosslinking of polyurethane when irradiated by gamma-rays

We conducted a study to clarify the mechanism of crosslinking and degradation of thermoplastic polyurethane (PU) when irradiated with gamma-rays. Changes in molecular weights as a result of gamma-ray irradiation, the UV absorption, the amount of PUs with amino groups, and the elution of oligomers to an organic solvent were determined to estimate characteristic changes in PU caused by irradiation. The amount of PUs with primary amino groups as a degradated PU products at p,p′-methylenediphenyl diisocyanate–1,4-butanediol (MDI–BU) hard segments increased linearly with increasing irradiation level. The amount of this products by gamma-ray irradiation was approximately 10–20% of the calculated amount, indicating that predominant degradation occurred at polytetramethyleneglycol (PTMG) soft segments (about 80–90% of the degradation). Characteristic differences were seen in crosslinking between non-chain-extended thermoplastic PUs based on the molecular weights of PTMG, (M_w of PTMG = 640–2800). The crosslinking ratio is linearly proportional to the molecular weights of PTMG, indicating that crosslinking at PTMG soft segments was major (the ratio of crosslinking at PTMG was more than 90%). Methanol extract of PU indicated elution of PU oligomers ranging from 13 to 1 as a polymerization degree.     

Synthesis of novel block copolymers containing polyamide4 segments and control of their biodegradability

Different novel copolymers, ABA‐type block copolymers composed of polyamide4 as outer segments and polyoxyethylene as an inner segment and AB‐ and ABA‐type block copolyamides containing polyamide4 and another hydrophilic polyamide derived from a bicyclic lactam, were synthesized by the anionic ring‐opening polymerization of 2‐pyrrolidone using the corresponding acyllactam‐type macromolecular activators. The degradation rate of both block copolymers containing polyamide4 segments in a composted soil was found to decrease with increasing content of the second segments, although they were also hydrophilic and/or biodegradable. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3492–3498, 2004     

超声波降解对丙烯基塑性体性能的影响

利用自制的超声波辐照装置,对一种新型丙烯基塑性体(简称DP)熔体进行超声波降解,研究了超声波降解对DP结晶性能、力学性能和流变性能的影响。与等规聚丙烯相比,DP的结晶性能差,屈服拉伸强度低,但断裂伸长率明显提高。在超声波辐照下,DP熔体发生力化学降解,无规断链主要集中在高相对分子质量部分,相对分子质量分布变宽,大分子结构中出现羰基。超声波降解产生的低相对分子质量链段活动能力和极性增强,可在较高温度下结晶。另外,超声波降解也会导致DP的屈服拉伸强度下降,表观黏度降低。     

Cross-linked degradable poly(β-thioester) networks via amine-catalyzed thiol-ene click polymerization

A set of binary and ternary biodegradable cross-linked poly(β-thioester) networks have been synthesized via thiol-ene Michael additions, by reacting combinations of dithiols, diacrylates and multifunctional cross-linkers. Insoluble binary thermoset networks and soluble ternary branched polymers with broad molar mass distributions are obtained in a facile manner after polymerization at room temperature for only few minutes. The networks display excellent thermal stability up to 250 °C and exhibit low glass transition temperatures. The soluble branched polymers show degradation of the polyester backbone upon chemical degradation by acidic and basic solutions. Finally, the (bio)degradability of ternary PBT polymer films is examined via quartz crystal microbalance measurements. Weight loss is measured as a function of time upon exposure to phosphate buffers at different pH. PBTs carrying apolar chain segments display surface degradation, while PBTs with more polar ethylene glycol segments allow for swelling in aqueous solution, which is reflected in concomitant surface and bulk degradation of the materials. Because of their biodegradability, these easy to synthesize poly(β-thioesters) networks are considered to be suitable candidates to use in future biomedical or ecological applications.