私密直播全婐app免费大渔直播,国产av成人无码免费视频,男女同房做爰全过程高潮,国产精品自产拍在线观看

相關鏈接
聯系方式
  • 通信地址:加拿大魁北克省蒙特利爾
  • 郵編:無
  • 電話:(514) 848-2424 ext.5611
  • 傳真:
  • Email:zhibin.ye@concordia.ca
當前位置:> 首頁 > 論文著作 > 正文
‘Arm-first’ synthesis of core-crosslinked multiarm star polyethylenes by coupling Pd-catalyzed ethylene ‘living’ polymerization with atom-transfer radical polymerization
作者:P. Liu, E. Landry, Z. Ye*, H. Joly, W.-J. Wang*, B.-G. Li
關鍵字:無
論文來源:期刊
具體來源:Macromolecules
發表時間:2011年

We report in this article the “arm-first” synthesis of coreshell-structured multiarm polyethylene (PE) star polymers having multiple linear-but-branched PE arms joined at a cross-linked polydivinylbenzene (polyDVB) core. This synthesis is achieved in two steps by coupling two mechanistically incompatible polymerization techniques, Pd-catalyzed coordinative ethylene “living” polymerization and atom-transfer radical polymerization (ATRP). Ethylene “living” polymerization was first carried out using a functionalized Pddiiminecatalyst[(ArNdC(Me)(Me)CdNAr)Pd(CH2)3C(O)O(CH2)2OC(O)C(CH3)2Br]tSbF6 (Ar = 2,6-(iPr)2C6H3) (1), to directly synthesize narrow-distributed PE macroinitiators (MIs) containing an end-capping 2-bromoisobutyryl group active for initiating ATRP. Featured with controllable molecular weights at low polydispersity, the PE MIs are employed subsequently in the second step to initiate crosslinking polymerization of divinylbenzene (DVB) via ATRP to obtain the core-cross-linked star polymers. As a demonstration, threePE MIs at different lengths (number-average molecular weight of 7.3, 10.3, and 13.7 kg/mol, respectively) were specifically synthesized and employed for star construction. In the ATRP step, the effects of the various polymerization parameters, including MI concentration, the molar ratio of DVB to MI, and MI length, on the polymerization kinetics, star yield, average arm number, and average molecular weights of the star polymers were investigated systematically. By controlling the polymerization parameters, a range of PE star polymers having narrow-distributed arm lengths (7.313.7 kg/mol) and controllable average arm numbers (ca. 543 per star) have thus been successfully synthesized. A study on dilution solution properties of these star polymers having various structural parameters reveals their spherical chain conformation and resemblance of rigid spheres and high-generation dendrimers, with their intrinsic viscosity depending primarily on arm length while not on arm number or polymer molecular weight.


主站蜘蛛池模板: 中牟县| 黄平县| 新干县| 台安县| 吉安县| 曲麻莱县| 嵩明县| 菏泽市| 云安县| 克东县| 民县| 临高县| 榕江县| 镇雄县| 屯门区| 伊宁县| 凤山市| 崇信县| 福海县| 于田县| 青铜峡市| 调兵山市| 响水县| 肥西县| 缙云县| 蛟河市| 革吉县| 射洪县| 钟祥市| 沛县| 阿荣旗| 平乡县| 玛纳斯县| 绿春县| 利津县| 金山区| 侯马市| 湘西| 江西省| 哈密市| 常山县|