RAFT polymerization of methyl 6-O-Methacryloyl-α-D-glucoside in homogeneous aqueous medium.: A detailed kinetic study at the low molecular weight limit of the process
RAFT polymerization of methyl 6-O-Methacryloyl-α-D-glucoside in homogeneous aqueous medium.: A detailed kinetic study at the low molecular weight limit of the process
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DOI：
10.1021/ma070967o
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发表时间：
2007-08-21
期刊：
影响因子：
5.5
通讯作者：
Cameron, Neil R.
中科院分区：
文献类型：
--
作者：
Albertin, Luca;Cameron, Neil R.
研究了甲基丙烯酸酯型糖基共聚单体6-O-甲基丙烯酰基-α-D-葡萄糖苷（6-O-methacryloyl-alpha-D-glucoside，6-O-methacrylyl-alpha-D-glucoside，6-O-methacrylyl-alpha-D-glucoside，6-O-methacrylyl-alpha-D-glucoside）在链转移剂（CTA）（4-氰基戊酸）-4-二硫代苯甲酸酯（4-cyanopentanoic acid，4-氰基戊酸）和引发剂4，4 ′-偶氮二（4-氰基戊酸）存在下的RAFT聚合动力学。研究了温度、引发剂和CTA浓度、CTA自由基离去基团的摩尔质量以及残余氧的存在对聚合动力学的影响，并与相应的常规自由基聚合（即，不存在CTA）。RAFT过程的特征在于由一个初始的非稳态期间，其长度与系统中的自由基通量成反比，并被发现进行在一个显着较慢的速度比相应的常规自由基聚合。此外，达到稳态与初始CTA的完全消耗一致。大分子CTA的使用减少了非稳态期的长度，但有趣的是，没有消除它，并且该期的持续时间仍然显示出与初始CTA与引发剂的比率成反比。据我们所知，这是第一次，一个非稳态期间已被观察到在RAFT聚合引发的大分子CTA。最后，本研究的结果被用来作为指导的一系列明确的活性糖低聚物（DPn = 15 - 66，PDI = 1.05 - 1.12），在高产率的制备。
We report a detailed kinetic study of the RAFT polymerization of methyl 6-O-methacryloyl-alpha-D-glucoside (a methacrylic ester-type glycomonomer) with the chain transfer agent (CTA) (4-cyanopentanoic acid)-4-dithiobenzoate and initiator 4,4'-azobis(4-cyanopentanoic acid) in homogeneous aqueous media. The influence of temperature, initiator and CTA concentration, molar mass of the CTA radical leaving group, and the presence of residual oxygen on the polymerization kinetics were investigated in comparison with corresponding conventional free radical polymerizations (i.e., with no CTA present). RAFT processes were characterized by an initial non-steady-state period, the length of which depended inversely on the radical flux in the system, and were found to proceed at a significantly slower rate than the corresponding conventional free radical polymerizations. Also, attainment of the steady-state coincided with complete consumption of the initial CTA. The use of a macromolecular CTA reduced the length of the non-steady-state period but, interestingly, did not eliminate it, and the duration of this period was still shown to depend inversely on the initial CTA to initiator ratio. To our knowledge, this is the first time that a non-steady-state period has been observed in a RAFT polymerization initiated by a macromolecular CTA. Finally, the results of this investigation were used as a guide for the preparation of a series of well-defined living glyco-oligomers (DPn = 15-66, PDI = 1.05-1.12) in high yield.