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: 永福县| 东乡族自治县| 行唐县| 固安县| 招远市| 文水县| 徐州市| 万州区| 平遥县| 新巴尔虎右旗| 米易县| 灵台县| 中西区| 河曲县| 北票市| 望奎县| 房产| 凉城县| 额济纳旗| 青海省| 浏阳市| 屏山县| 凌云县| 凯里市| 武穴市| 邵阳县| 惠安县| 温州市| 呼伦贝尔市| 安康市| 江口县| 洛阳市| 常熟市| 榆中县| 衢州市| 正安县| 凉城县| 桃源县| 舟曲县| 成都市| 三门县|