Control over controlled radical polymerization processes

A method of polymerizing unsaturated monomers, comprising:

• (a) mixing unsaturated monomers with an inactive metal catalyst, optionally ligand and an initiator having a transferable atom, wherein the inactive metal catalyst is present in the mixture at an amount of less than 250 ppm, on a mass basis relative to the total mixture;
• (b) heating the mixture to a reaction temperature;
• (c) adding a first portion of a non-activated reducing agent to the system to generate an activated reducing agent, wherein the non-activated reducing agent has a decomposition activation-dependent t1/2 value of between 30 sec. and 30 min. at at least one of the reaction conditions;
• (d) reducing the inactive metal catalyst with the activated reducing agent to form an active metal catalyst;
• (e) transferring the transferable atom with the active metal catalyst, thereby activating the initiator for unsaturated monomer addition;
• and
• (f) adding at least a further portion of the non-activated reducing agent to the mixture to induce further polymerization of the unsaturated monomer;
• wherein the at least further portion is added to the mixture at a point where at least 30 molar %, relative to the amount of unsaturated monomer introduced into the mixture, has been polymerized, and
• wherein at least one polymer product has a degree of polymerization, with respect to the monomer residues corresponding to the unsaturated monomer, of at least 20 and the overall mixture has a conversion of at least 60 molar % relative to the amount of unsaturated monomer introduced into the mixture.

A method of radical polymerization of an unsaturated monomer, comprising:

• (a) polymerizing an unsaturated monomer in a system comprising an initiator, optionally ligand and a metal catalyst at or above a reaction temperature;
• (b) adding at a controlled rate a first amount of non-activated reducing agent to the system;
• and
• (c) controlling the rate of polymerization of the unsaturated monomer by adding at a controlled rate a further amount of the non-activated reducing agent to the system at a point where at least 30 molar %, relative to the amount of unsaturated monomer introduced into the system, has been polymerized;
• wherein at least one reaction conditions is at or above a point suitable to trigger the decomposition of the non-activated reducing agent to form an active reducing agent.

A method of making a polymer, comprising:

• (a) preparing a reaction mixture comprising a radically-polymerizable unsaturated monomer, an initiator, optionally ligand and an inactive metal catalyst in a molar ratio of the unsaturated monomer to the initiator of 25-5000:1 and a molar ratio of the catalyst to the initiator of 0.001 to 0.5:1 and the inactive metal catalyst is present in the mixture at an amount of less than 250 ppm, on a mass basis relative to the total mixture;
• (b) heating the reaction mixture to a first temperature;
• (c) disbursing a portion of a thermo-activated reducing agent into the heated reaction mixture;
• (d) allowing a quantity of said portion of the thermo-activated reducing agent to decompose to an activated reducing agent;
• (e) reducing a portion of the inactive metal catalyst with a portion of the activated reducing agent to form at least one active metal catalyst;
• (f) activating one or more of the initiators with the at least one active metal catalyst to form one or more activated initiators;
• (g) polymerizing at least one monomer in the presence of one or more activated initiators to extend a polymer chain;
• and
• (h) repeating steps (c)-(g) while maintaining the temperature at or above a second temperature;
• wherein the first and second temperatures are at or above a temperature wherein the thermo-activated reducing agent has a temperature-dependent t1/2 value of between 30 sec. and 30 min.