Copolymers of -caprolactone (CL) and trimethylene carbonate (TMC) have been synthesized through ring-opening polymerization using a novel initiator of scandium tris (2,6-di-tert-butyl-4-methylphenolate). CL and TMC polymerizations proceed via the "coordination anionic mechanism" with acyloxygen bond cleavage. Five kinds of copolymers with different structures of X, XB, AXB, AB, and BAXB are synthesized under different polymerization conditions and characterized by 1H NMR, GPC, and DSC, where X, A, and B denote as random blocks of CL and TMC, PTMC blocks, and PCL blocks, respectively.

The ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated with highly active single rare earth tris(2,6-di-tert-butyl-4-methylphenolate) (Ln(OAr)3, Ln=La, Nd, Dy, Y) is reported for the first time. The catalytic activities of various Ln(OAr)3 systems are decreasing in the following sequence: La>Nd>Dy～Y. PolyDTC (Mw=17.1×104, MWD=2.79) initiated by La(OAr)3 at [DTC]/[initiator]=1000 was obtained with a conversion of 97.9% within 1 h in toluene at 15℃. 1H NMR, GPC, and DSC are used to characterize the polymer's structure and to investigate the polymerization mechanism. PolyDTC obtained has no ether unit developed from CO2 elimination. The polymerization of DTC occurs according to a coordination anionic mechanism, and the ring is opened via acyl-oxygen cleavage leading to an Ln-O active center.

tically suppress the transesterification reactions by screening linear polymer chains from the active center during the polymerization of є-caprolactone (CL) with rare earth alkoxide. Therefore, isopropoxy rare earth diethyl acetoacetate ((EA)2LnOiPr Ln=Nd, Y) and Nd(OiPr)3-donor adducts (1,10-phenanthroline, 2,2¢-bipyridyl, 18-crown-6 ether) are excellent catalysts for the living polymerization of є-caprolactone, giving poly(є-caprolactone) (PCL) with a narrow molecular weight distribution. Block copolymerizations of є-caprolactone with trimethylene carbonate (TMC) and D,L-lactide (LA) have been attained successfully using (EA)2LnOiPr as catalyst. The characterizations by GPC, NMR, DSC, and polarizing microscope showed that the block copolymers, P(CL-b-TMC) and P(CL-b-D,L-lactide), have well-controlled sequences without random placement.

Ring-opening polymerization of є-caprolactone catalyzed by rare earth halides and rare earth halide-epoxide has been carried out for the first time. It was found that rare earth halides have low activities for the polymerization of є-caprolactone, but in the presence of epoxide, rare earth halides are highly active for the bulk and solution polymerization of є-caprolactone, with high molecular weight poly-(-caprolactone) (PCL) formed. With the NdCl3-20PO system, PCL with a molecular weight of 22.4×104 can be easily obtained at 30℃, and the molecular weight of PCL can be increased to 42×104 at 60℃ with a catalyst efficiency of 100×104g of PCL/mol of NdCl3. The catalytic activities of the rare earth halides are affected by the kind of rare earth element, halogen, epoxide, amount of added epoxide, catalyst concentration, and polymerization temperature. It has been found that rare earth halides react with epoxide and produce halogen rare earth alkoxides: (X3-xLn{[OCH(R)CH2]yX}x, X=Cl, Br, I). A study on the polymerization mechanism showed that the resulting rare earth alkoxide bond initiates the polymerization of є-caprolactone via a "coordination-insertion" mechanism with acyl-oxygen bond cleavage of the monomer during the є-caprolactone polymerization catalyzed by rare earth halide-epoxide.

Copolymerzation of proplene oxide and carbon dioside was successfully carried out by using new rare-earth catalytic systems for the first time. It has been found that ternary rare-earth coordination catalysts composed of rare-earth phosphonat, triisobutylaluminum, and glycerine are effective catalysts for the copolymerixation. The system Y(P204)3-Al(i-Bu)3-glycerine shows the highest activity. The yield and interinsic viscosity of the copolymer depend significantly on the molar ratio of catalyst components and the reaction condition. The copolymers prepared were characterizaed by IR, 1HNMR, GPC. and DTA-TGA. It is showed that the copolymers obtained have a high molecular weight with a narrow molecular weithg distribution is showed that the copo;ymers obtained have a high molecular weitht with a narrow molecular weith distribution and a high thernmal stsbility. The carbonat unit content of the methanol-insoluble copolymer is as high as 30-40%.

Rare earth catalysts represem an unprecedemed case where either butadiene, isoprene or mixtures of butadiene and isprene can be polymerzed to elastomers with high content of cis-isomer and good properties. As high as 98% cis-polyacetylene films with metallic sheen can be prepared by rare earth catalysts are excellent as high cis-stereospecific polymerixzation catalysts for acetylenes. High molecular weight polyepoxides can also be prepared by rare earth catalysts.

本文首次研究了应用稀土化合物作乙炔定向聚合催化剂，发现除钜外所有15个镧系元素的环烷酸盐或2-乙基已基膦盐酸与三烷基铝基合成的络合催化剂都可以使乙炔写向聚合。其物点是乙炔在室温（30℃～0℃）下聚合，便能制得高顺式（80%～100%）、具有金属光汉的银灰色聚乙炔薄膜，显示稀土络合催化剂是一类合成高顺式聚乙炔极其方便的优良催化剂。本文报道乙炔在膦酸稀土盐和环烷酸稀土催化剂中定向聚合特征，以及用红外光谱、热分析、顺磁共振、X衍射、扫描电子显微镜及电阻率测定等对所制备的烯土聚乙炔薄膜初步表片的结果。

本文研究了丁二烯-异戊二烯氯化稀土-三烷基铝催化体系中共聚合的规律。从聚合物的玻璃化温度和热裂解色谱证明了聚合产物确系共聚物。共聚速率方程可表示为：Rp=Kp[M]2[cat]。测定了丁二烯与异戊在Ⅲ-B族钪、钇和镧系元素在不同溶剂催化体系中的共聚速率常数、表观活化能及竞聚率。各种体系中都得到γ1（丁二烯）＞1，γ（异戊二烯）＜1，γ1·γ2接近于1的结果。用统计方法对共聚物的序列分布了讨论，证明共聚物中同种单体两单元以下连结的链节约占60-70%，说明生成的是无规共聚物。共聚物的组成和结构随条件变化而变化的范围不大，其中丁二烯与异成二烯链节的顺-1，4含量，一般都在95%以上。