Molecular Weight Distribution of Living Polymerization Involving Chain-Transfer Agents: Computational Results, Analytical Solutions, and Experimental Investigations Using Ring-Opening Metathesis Polymerization

1995 ◽  
Vol 28 (2) ◽  
pp. 500-511 ◽  
Author(s):  
Alto D. Benedicto ◽  
Jerome P. Claverie ◽  
Robert H. Grubbs
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Analytical Solutions ◽  
Weight Distribution ◽  
Ring Opening ◽  
Chain Transfer ◽  
Living Polymerization ◽  
Experimental Investigations ◽  
Computational Results ◽  
Metathesis Polymerization

Controlled/‘living’ polymerization methods

2004 ◽  
Author(s):  
Wayne Hayes ◽  
Steve Rannard
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Chain Transfer ◽  
Living Polymerization ◽  
Degree Of Polymerization ◽  
Polymer Chains ◽  
Chain Growth ◽  
Living Polymerizations ◽  
Living Nature

Chain-growth polymerizations such as free-radical polymerizations are characterized by four key processes:(i) initiation, (ii) propagation, (iii) chain transfer, and (iv) termination. If it is possible to minimize the contribution of chain transfer and termination during the polymerization, it is possible to achieve a level of control over the resulting polymer and achieve a predetermined number average molecular weight and a narrow molecular weight distribution (polydispersity). If such an ideal scenario can be created, the number of polymer chains that are produced is equal to the number of initiator groups; the polymerization will proceed until all of the monomer has been consumed and the polymer chain ends will remain active so that further addition of monomer will lead to continued polymerization. This type of polymerization was termed a ‘living’ polymerization by Szwarc in 1956 and represents one of the ultimate goals of synthetic polymer chemists. Flory determined that in the absence of termination, the number of propagating polymer chains must remain constant and that the rate of polymerization for each growing chain must be equal. In this situation, the number average degree of polymerization (DPn) and hence the molecular weight of the polymer can be predicted by simple consideration of the monomer to initiator ratio (see eqns (1) and (2), respectively). Several key criteria are used to elucidate the ‘living’ nature of a polymerization. For a polymerization to be considered ‘living’, the rate of initiation must exceed the rate of propagation. Therefore, all the propagating polymer chains are formed simultaneously and grow at the same rate. If this situation did not occur, the first chains formed would be longer than those initiated later and the molecular weight distribution of the propagating chains would broaden. In addition, an ideal ‘living’ or ‘immortal’ polymerization must not exhibit any termination of the propagating polymer chains over the lifetime of the reaction. Consequently, ‘living’ polymerizations are characterized by very narrow molecular weight distributions (Mw/Mn < 1.2).

Molecular weight distribution and controllability in living polymerization with chain-transfer agents

Polymer ◽  
1998 ◽  
Vol 39 (13) ◽  
pp. 2789-2793 ◽  
Author(s):  
Jin-Wuk Kim ◽  
Ki-Jun Lee ◽  
Hong H. Lee
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Chain Transfer ◽  
Living Polymerization ◽  
Transfer Agents

Controlled and Efficient Polymerization of Methyl Methacrylate Catalyzed by Pyridinylidenaminophosphines Based Lewis Pairs

2021 ◽  
Author(s):  
Fang Ge ◽  
Sun Li ◽  
Zhe Wang ◽  
Wenzhong Zhang ◽  
Xiaowu Wang
Keyword(s):  
Molecular Weight ◽  
Methyl Methacrylate ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Living Polymerization ◽  
Narrow Molecular Weight Distribution ◽  
Synthetic Approaches ◽  
Lewis Pairs

Developing different synthetic approaches to realize controlled or living polymerization are aspirational to achieve polymers with defined molecular weight, narrow molecular weight distribution and unambiguous structures by polymer chemists. Herein,...

Effect of chain transfer with fracture on the molecular weight distribution of polymers and oligomers

1965 ◽  
Vol 7 (10) ◽  
pp. 2015-2020 ◽  
Author(s):  
V.V. Ivanov ◽  
A.A. Shaginyan ◽  
V.P. Volkov ◽  
N.S. Yenikolopyan
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Chain Transfer
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