双烯类聚合物的热分析——Ⅲ.铁与其它催化体系聚1,2-丁二烯及其衍生物的热分析

<正> 由不同催化体系制得的聚1,2-丁二烯,由于其立体规整性(如等规、间规和无规)不同,其形态、热学性质也会有所不同。关于它们的热学性质文献报道不多。我们曾报道,由三乙酰基丙酮钴-三异丁基铝-二硫化碳催化体系制备的间规聚1,2-丁二烯是晶态的;而由正丁基锂和MoCl_4OR-(i-Bu),AlOR′制得的是无规聚1,2-丁二烯;是非晶态     

含氯化合物对丁二烯定向聚合的作用

本工作研究了氯代正丁烷、氯代异丙烷、氯代叔丁烷、氯仿、四氯化碳、二氯甲烷、氯化苄、氯代苯、四氯化碳等对丁二烯用三异丁基铝及四碘化钦催化聚合的影响。结果指出,氯代正丁烷或氯代异丙烷能引起凝胶的生成。氯代叔丁烷或氯化苄能抑制聚合。氯仿或四氯化碳能降低产物分子量,但后者同时使聚合转化率降低。四氯化钛既降低产物分子量又改变产物结构。氯代苯或二氯甲烷则对聚合几无影响。为阐明上述现象,本工作还研究了上述合氯化合物与三异丁基铝的反应。结果指出,氯化苄或氯代叔丁烷均能与三异丁基铝瞬时反应生成氯离子。氯代苯或二氯甲烷等则反应很少,氯代正丁烷或氯代异丙烷须经一诱导期后与三异丁基铝爆发反应生成大量氯离子。经实验证明,氯代正丁烷或氯代异丙烷引起凝胶生成的原因即在于当时所生成的三氯化铝引起交联的结果。     

环氧氯丙烷与环氧乙烷及环氧丙烷的三元共聚

研究了用三异丁基铝-磷酸-含氮含硫给电子化合物作为催化剂使环氧氯丙烷、环氧乙烷及环氧丙烷三元共聚的行为。结果指出,作为催化剂第三组分以二甲基苯胺的效果最好。催化体系中存在与磷酸相等克分子的水时催化活性较高。酸铝比在0.25及胺铝比在0.2时活性最高。三异丁基铝用量占总单体重量的2.5％,70℃,4小时聚合转化率可达95％左右,共聚物的η_i达到2附近。通过共聚物氯含量的测定及利用核磁共振波谱仪测定环氧丙烷链节含量,求得共聚过程中各单体组分的变化。固定单体中环氧氯丙烷配比,改变环氧丙烷及环氧乙烷配比,则随环氧丙烷比例增加,所得共聚物η_i下降,T_g呈现最小值的变化。     

聚合物载体-稀土金属络合物的研究III.用聚合物载体-钕络合物-氯代烷-三异丁基铝催化体系聚合共轭双烯

研究了聚合物载体-钕络合物-氯代烷-三异丁基铝新体系用于共轭双烯的聚合,所用载体为苯乙烯-丙烯酸共聚物。丁二烯聚合时体系的催化活性的大小既取决于氯代烷的种类,又与配制催化剂的溶剂有关。聚合物载体-钕络合物体系的活性高于小分子异辛酸钕和环烷酸钕体系。氯代烷的种类不影响所得聚合物的微观结构。体系保持了小分子稀土催化剂所具有的良好定向效应,所得聚丁二烯的顺式-1,4结构含量高于98%。采用这一体系得到的聚异戊二烯的顺式-1,4结构含量在96%左右。载体本身的组成及其络合物中稀土的含量对体系的活性影响很大。     

用简易凝胶渗透色谱柱研究氯醇橡胶

用简易GPC柱研究了三种类型氯醇弹性体的分子量分布。装柱填料是多孔硅胶球。理论塔板数2000块/米以上。用三异丁基铝-磷酸-水-二甲基苯胺催化剂制得的均聚氯醇胶比用三异丁基铝-磷酸-苯并噻唑亚磺酰胺所得氯醇胶分子量分布宽,宽度指数在3—6之间。均聚氯醇胶在素炼过程中,分子量分布变窄,分子量变低。转化率增加,单体浓度增加或温度降低使分布变宽。催化剂中的二甲基苯胺对三异丁基铝克分子比影响二元共聚胶的分布宽度。     

在Nd(OCt)3*-HAl(i-Bu)2-CH2-CHCH2Cl均相催化体系下的丁二烯聚合动力学

本文研究了丁二烯在2-乙基己酸钕-氢化二异丁基铝-烯丙基氯均相催化体系下的聚合动力学。实验结果表明,聚合速率对单体浓度和主催化剂浓度均为一级关系,对氢化二异丁基铝浓度呈1/3级关系。测得了丁二烯在本体系中聚合的表观与增长活化能以及活性中心数目。     

在Nd(OCt)_3~*-HAl(i-Bu)_2-CH_2-CHCH_2Cl均相催化体系下的丁二烯聚合动力学

本文研究了丁二烯在2-乙基己酸钕-氢化二异丁基铝-烯丙基氯均相催化体系下的聚合动力学。实验结果表明,聚合速率对单体浓度和主催化剂浓度均为一级关系,对氢化二异丁基铝浓度呈1/3级关系。测得了丁二烯在本体系中聚合的表观与增长活化能以及活性中心数目。     

合成氯醇橡胶催化剂——三异丁基铝-磷酸-叔胺催化体系

我们曾报导过三异丁基铝-磷酸-噻唑亚磺酰胺组成的催化体系对环氧氯丙烷均聚及环氧氯丙烷与环氧乙烷的共聚有相当高的催化活性,比一般常用的三异丁基铝-水-乙醚体系的催化效率高达十倍左右。后来我们进一步做了些工作,发现三异丁基铝-磷酸-叔胺组成的体系对环氧氯丙烷均聚及共聚也具有很高的催化活性。叔胺的成本一般较噻唑亚磺酰胺为低,而且是液体,在催化剂配制上较为方便。在我们工作的后期,看到日本专利中也有报导三异丁基铝-磷酸-叔胺催化体系的,但催化剂的配制方法有所不同,所举例子活性显得较我们的工作结果为低。     

丁二烯-异戊二烯嵌段共聚物的分子量表征

稀土络合催化体系用于丁二烯-异戊二烯的定向聚合研究在我国已取得了显著成绩,但有关分子量测试工作却很少研究。关于该催化体系合成的高顺式1,4-丁二烯-异戊二烯嵌段共聚物的分子量表征工作未见报道。本文采用GPC和[η]测定方法表征了丁二烯-异戊二烯嵌段共聚物的分子量。     

VO(OR)2Cl-Al(t-Bu)3催化丁二烯丙烯交替共聚机理的探讨

本文用电位滴定测定了钒的价态,与共聚合活性数据对照,认为活性中心主要是V⁺³离子;用IR测定了Al-O-V、Al→O和V-Cl后,提出活性中心为带Al-Cl-V、Al-O-V桥的钒中心正八面体结构。结合log[η]对1og(D₈₉₀/D₉₇₀)的线型关系推断交替共聚物的端基为β-甲基乙烯基,在此基础上提出了可能的引发、增长和终止机理。     

Alternating copolymer of butadiene and propylene. III

Alternating copolymerizations of butadiene with propylene and other olefins were investigated by using VO(acac)₂–Et₃Al–Et₂AlCl system as catalyst. Butadiene–propylene copolymer with high degree of alternation was prepared with a monomer feed ratio (propylene/butadiene) of 4. Alternating copolymers of butadiene and other terminal olefins such as butene-1, pentene-1, dodecene-1, and octadiene-1,7 were also obtained. However, the butadiene–butene-2 copolymerization did not yield an alternating copolymer but a trans-1,4-polybutadiene.     

二氧化碳基脂肪族聚碳酸酯的功能化研究进展

简要介绍了二氧化碳基塑料的工业化进程,同时针对当前二氧化碳共聚物结构中缺少可反应基团、难以进行化学修饰导致的品种和功能单一、亲水性差等问题,介绍了二氧化碳基脂肪族聚碳酸酯的功能化研究进展,主要包括侧链含有双键、碳酸酯键和液晶基团的侧基功能化二氧化碳共聚物的合成与性能研究,以及二氧化碳共聚物的亲水性调制和刺激响应行为探索,试图为丰富二氧化碳基聚碳酸酯结构和性能提供借鉴.     

Alternating stereospecific copolymerization of ethylene and propylene with metallocene catalysts

The copolymerization of ethylene and propylene with bridged metallocenes Me(2)E(3-RCp)(Flu)X(2)/MAO (E = C, X = Me; E = Si, X = Cl; R = H or alkyl) was investigated. Ethylene/propylene copolymerization with metallocenes having heterotopic active sites (R =Me, i-Pr) yield alternating, isotactic ethylene/propylene copolymers with percentages of alternating EPE+PEP triads in the range of 61-76% at 50% ethylene incorporation. Both the nature of the substituent R and the bridge E influence the copolymerization behavior including the copolymerization activity, copolymer sequence distribution, molecular weight, and stereochemistry. Silicon-bridged metallocenes produce copolymers with higher activity and molecular weight but lower propylene incorporation at similar feeds than the carbon-bridged analogues. Isotactic PEPEP sequences were observed for all metallocenes, while the tacticities of the EPPE sequences varied with the bridge and the substituent on the metallocene ligand. Isotactic PEPEP sequences and atactic EPPE sequence errors in the alternating copolymers are consistent with a mechanism where the comonomers are enchained alternately at the heterotopic coordination sites of the metallocenes. Isotactic EPPE sequences are indicative of occasional multiple insertions at the stereospecific site, caused by an isomerization of the chain prior to monomer insertion (backskip).     

Alternating copolymer of butadiene and propylene. IV. Studies on the catalysts for alternating copolymerization

The catalysts for alternating copolymerization of butadiene and propylene were investigated by means of ESR technique and potentiometric titration. It was found that several kinds of active species for the production of alternating copolymer, 1,2-polybutadiene, and trans-1,4-polybutadiene are formed, depending upon the catalyst composition of VO(acac)₂? Et₃Al? Et₂AlCl. ESR and potential titration studies suggest that the active species for alternating copolymerization is a divalent vanadium compound existing in an associated form.     

Hydrogenated 1,4-insertion of butadiene in the copolymerization with propylene using an isospecific zirconocene catalyst

Poly(propylene-ran-1,3-butadiene) that contained pendant vinyl groups derived from 1,2-inserted butadiene units was selectively synthesized by rac-dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride (Ph-Ind) activated with modified methylaluminoxane (MMAO) in the presence of hydrogen. The copolymers obtained without hydrogen had 1,2-inserted and 1,4-inserted butadiene units. The addition of hydrogen to the copolymerization improved the activity by approximately 1000-fold and gave the copolymer only with 1,2-inserted butadiene units, of which the content was equal to the copolymer obtained without hydrogen. The 13C NMR analysis of the copolymers clarified that butadiene also inserted into the copolymer as a tetramethylene unit, of which the content was almost the same as that of 1,4-inserted butadiene units observed in the absence of hydrogen. No signal that could be assigned to cyclic structures or long branched side chains was observed. These results indicate that pi-allyl species of zirconocenes formed by 1,4-butadiene insertion at the growing polymer chain ends transformed to the tetramethylene chain end by hydrogenation and continued successive propylene insertion.     

载体型钛系催化剂的丙烯与乙烯共聚合研究

以载体型钛系齐格勒-纳塔催化剂进行了丙烯和乙烯无规共聚合的研究。对聚合温度、铝钛摩尔比、给电子体浓度和加氢等行为作了考察。共聚合速度和共聚物的比浓粘度呈规律性变化。用~(13)C-NMR和DSC测定了共聚物的组成、序列分布、熔点和结晶度.结果表明,在共聚合反应速度曲线上,在丙烯和乙烯分别为10mol％组成处,出现两个最大值。随共聚物中乙烯含量增加(2—10mol％),其熔点和结晶度降低,DSC峰变低、变宽,在乙烯含量达10mol％处出现双峰(128/116℃)反映出无规共聚链出现不同的序列分布。     

接枝共聚物EPR-g-PS作PS/EPDM共混体系增容剂的探讨

使用了由大分子单体共聚合制备的以乙丙橡胶(EPR)为主干、聚苯乙烯(PS)为支链的接枝共聚物EPR-g-PS作为PS/EPDM共混体系的增容剂。实验结果表明,共混体系的组成、增容剂加入量以及增容剂分子结构对共混体系冲击强度有很大影响。将这些因素与相差显微镜及扫描电镜研究所揭示的共混物形态的变化相联系,对此类接校共聚物作为不相容体系增容剂的机理作了探讨。     

BF_3,络合的丙烯酸乙酯与丙烯的共聚机理

BF_3络合的丙烯酸乙酯(EA)与丙烯(P)在25℃进行自由基共聚。聚合速率和引发剂浓度的平方根成直线关系。链转移剂CCl_4可显著影响共聚物的[η];溶剂的介电常数越小,共聚反应速率越大;两种单体浓度相等时共聚反应速率最大。~1H-NMR和 _13C-NMR表明,当[EA·BF_3]/[EA·BF_3]+[P]>O.5时所得共聚物为富于EA的无规共聚物。实验数据表明,共聚反应按三元络合物与二元络合物的无规共聚机理进行,当[EA·BF_3]/[EA·BF_3]+[P]<0.5时,得到交替共聚物,共聚反应按三元络合物均聚机理进行。UV光谱测得了戊烯-1(丙烯的同系物)与EA·BF_3三元络合物的存在,这对三元络合物的均聚机理是有力的证据。     

Donor-Acceptor Complexes in Copolymerization. XVIII. Alternating Diene–Dienophile Copolymers. 1. Conjugated Diene–Maleic Anhydride Copolymers through Radical-Catalyzed Polymerization

The copolymerization of isoprene, butadiene, and other conjugated dienes with maleic anhydride was readily initiated in polar solvents by conventional free radical catalysts, including peroxides, hydroperoxides, and azobisisobutyronitrile, at high concentrations or at temperatures at which the catalyst had a half-life of 1 hr or less and the total reaction time was 0.5-1 hr. Decreasing the reaction temperature or the rate of catalyst addition resulted in increased yields of Diels-Alder adduct and decreased yields of copolymer. The molecular weight decreased as the temperature increased. Dioxane and tetrahydrofuran peroxides, obtained by the passage of oxygen or UV irradiation in air, also initiated the copolymerization. The soluble diene-maleic anhydride copolymers were equimolar and alternating, had [n] 0.1-6 (cyclohexanone) and contained 75-95% 1,4 structure according to ozonolysis, titration with IC1 and NMR. The IR spectrum of the butadiene–maleic anhydride copolymer indicated 75-95% cis-1,4, 5-20% trans-1,4 and 0-5% 1,2-vinyl unsaturation. The proposed mechanism of polymerization involves a donor-acceptor (diene-dienophile) interaction generating a ground-state charge transfer complex which is readily converted to the cyclic adduct. Under the influence of radicals the ground-state complex is transformed into an excited complex which undergoes polymerization. High concentrations of radicals are necessary to generate polymerizable excited complexes in competition with adduct formation.