spontaneous synthesis of a homogeneous thermoresponsive polymer network composed of polymers with a narrow molecular weight distribution - polymer gel powder

by:Demi     2019-09-07
spontaneous synthesis of a homogeneous thermoresponsive polymer network composed of polymers with a narrow molecular weight distribution  -  polymer gel powder
We have developed a method to obtain a polymer gel consisting of a relatively uniform network structure consisting of narrow molecular weight polymers by simply mixing the necessary compounds.
In this method, the radical chain polymerization reaction with a rapid reaction rate is combined with the radical addition cross-reaction
A link reaction with a slow enough reaction speed compared to the polymerization reaction.
For polymerization reactions, star polymers with chain number and length determined by active radical polymerization were prepared using a multi-functional initiator with strict control over the number of polymerization initiation sites. In the cross-
Linked reaction, a multi-functional Terminator is used to prepare star polymers from narrow molecular weight polymers by active radical polymerization, and then coupling with multiple polymer chains using the termination reaction.
Therefore, only when all compounds are mixed and allowed to stand at a constant temperature, the two reactions with large kinetic differences occur in turn, and the relatively uniform network structure includes Cross
The connected polymer with low molecular weight distribution has an inherent structure.
Polymer gel by Crosslinked three-
Size polymer network of excessive solvent expansion.
Basic research using polymer gels has been conducted in different disciplines such as chemistry, physics, biology and pharmacology.
Applied research using polymer gels has also expanded to a wide range of areas including medicine, civil engineering, architecture, and space exploration.
In particular, there are two reasons why polymer gels are used in a wide range of basic and application fields.
First, anyone can obtain a polymer gel that exhibits similar properties by dissolving the necessary monomer and crossover
The connecting agent in the solvent, then degassing and introduce the initiator.
Secondly, the polymer gel obtained by this simple method has various functional properties such as molecular sieve separation capacity, super absorption capacity, slow release capacity and lens function.
Simply put, since everyone can easily prepare a variety of possible polymer gels, polymer gels have received interest as subjects of study, and their application studies have also been widely reported.
However, the polymer network of polymer gel prepared by traditional radical polymerization has a non-uniform network structure composed of polymer chains with different molecular weights (Scheme).
Therefore, the traditional polymer network may not be able to fully demonstrate the various functions of the polymer gel, such as molecular sieve partitioning capacity, mechanical strength, transparency, solvent retention capacity, stimulation responsiveness and biocompatibility.
If a polymer gel can be prepared from a polymer network consisting of monodisperse polymers, a gel with improved function can be obtained.
Previously, a linear, highly dispersed polymer was synthesized to try to construct a polymer gel with a network structure consisting of monodispersed polymersmolecular-
Weight, active monodisperse polymer and multi-functional cross polymerlinking.
Two other-
Step-by-step preparation methods are reported, such as the method of reacting the polymer precursor that constitutes a monodisperse polymer with four end reaction bases and then cross-reactionlinking them.
The polymer gel obtained by these methods has good mechanical properties and optical transparency.
If we can find a simpler method of synthesis, using a variety of other types of polymers to obtain a polymer gel with a network structure consisting of monodisperse polymers, then, compared to the gel previously studied, polymer gels with improved functions may be implemented.
In addition, the study of the application of polymer gels composed of monodisperse polymers in a wide range of fields will yield new discoveries.
In this work, we are trying to develop a method in which a network structure consisting of monodisperse polymers can be inherently synthesized by simply mixing the necessary compounds (Scheme).
In order to achieve this goal, the polymerization reaction with fast reaction rate and cross reaction
Compared to the polymerization reaction driven by the same catalyst, linked reactions with a sufficiently slow rate of reaction are combined.
With the development of active radical polymerization in recent years, many reactions that can produce various monodisperse polymers in a short period of time have been found.
For example, in a polymerization reaction
Propylene amine (NIPA)
Polymer with desired molecular weight and narrow molecular weight distribution using halogen organic compounds as initiator and copper catalyst (MWD)
Nearly 100% of production can be achieved in a few hours.
On the other hand, the same copper catalyst used in this polymerization can also catalyse the reaction of adding halogen-substituted organic compounds to propylene-based.
The catalyst achieved simultaneous chain growth and sequential polymerization by combining the addition reaction with the active radical polymerization.
Here, since the rate of the addition reaction is much slower than the rate of the polymerization reaction of the NIPA, when the initial concentration of the NIPA increases, the polymer with a narrow molecular weight is first formed by the active radical polymerization, then it becomes a periodic multi-block polymer through the addition reaction.
We think the reaction between halogen and halogen
Termination polymers prepared by the above active radical polymerization method and compounds with multiple propylene bases can be used as slow cross-over
Link response
From this perspective, we combine the multi-function initiation method and the multi-function termination method to prepare a polymer network consisting of narrow MWD polymers.
In the multi-functional termination method, polymer with relatively narrow molecular weight was prepared in advance by active radical polymerization, and then star polymer was prepared by coupling the termination reaction with multiple polymer chains.
After the necessary compound was mixed, two reactions with different reaction rates occurred in turn, trying to synthesize polymer gels with relatively uniform network structure from polymers with narrow MWD.
Therefore, we clarify a possible method of inherently constructing polymer gels consisting of relatively uniform network structures in which various types of narrow molecular weight polymer crosslinked.
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