Method for preparing gradient copolymer

A gradient copolymer and reactivity ratio technology, applied in the fields of polymer chemistry and emulsion polymerization, can solve the problems of wide particle size distribution, latex instability, and uncontrolled molecular weight distribution, and achieve narrow molecular weight distribution, controllable molecular weight, and reaction conditions. mild effect

Inactive Publication Date: 2010-08-04
WUHAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the migration of RAFT reagents in the aqueous phase often leads to problems such as latex instability, uncontrolled molecular weight distribution, and broad particle size distribution.
Ferguson et al. found that the use of amphiphilic RAFT reagents can effectively avoid the migration of RAFT reagents, and successfully produced triblock copolymers with a core-shell structure using this method [Macromolecules, 2005, 38, 2191-2204]. Attempts have been made in the preparation of copolymers

Method used

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  • Method for preparing gradient copolymer
  • Method for preparing gradient copolymer
  • Method for preparing gradient copolymer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] First disperse 5.0g dodecyl mercaptan and 0.54g tetrapropylammonium bromide in a mixed solvent consisting of 10ml water and 80ml acetone, and then add 1.0g sodium hydroxide and stir and heat to dissolve it. After room temperature, add 1.9g of carbon disulfide. After stirring for 30min, add 3.82g of dibromopropionic acid. Stir for more than 12 hours at room temperature and let it evaporate to 1 / 4 of its original volume. Then add hydrochloric acid (2M, 100mL) Slowly acidify, add 300mL of water to dilute, filter and wash to obtain the product, and finally recrystallize with petroleum ether and n-hexane to obtain the basic RAFT reagent S-1-dodecyl-S'-(α-methyl-α'-acetic acid) Trithiocarbonate. In the dry reactor, nitrogen gas was blown for 15 minutes and then S-1-dodecyl-S'-(α-methyl-α'-acetic acid) trithiocarbonate 1.75g, dioxane 8.98g and acrylic acid were added. 2.16g, V-501 initiator 0.14g, fully stirred to dissolve, start the water bath to heat up to 60℃, keep the reac...

Embodiment 2

[0039] In the dry reactor, nitrogen gas was added for 15 minutes, and then 47ml of water and 0.4692g S-1-dodecyl-S'-[(1,3,5,7,9,11,13-heptacarboxy)-fourteen Alkyl] trithiocarbonate (obtained according to the method of Example 1), after dissolving, add dropwise 2.6g of styrene, after fully pre-emulsification, add the initiator potassium persulfate (KPS) 0.0678g to dissolve, the water bath is heated to 70°C Begin to use a micro-injection pump to drop 5.9 g of hexafluorobutyl acrylate at a rate of 1.3 ml / h. After 6 hours of reaction, the system was cooled to room temperature and discharged. In the initial stage of the reaction, the polymerization rate is relatively slow. As the polymerization reaction time increases, the polymer conversion rate gradually increases. The obtained polymer emulsion has a pH value of 7, slightly yellow, no demulsification and layering phenomenon, and is still stable after being placed for 3 months. The conversion rate measured by the weight method is ...

Embodiment 3

[0041] Put nitrogen in the dry reactor for 15 minutes and then add 47ml of water and 0.0782g of S-1-dodecyl-S'-[(1,3,5,7,9,11,13-heptacarboxy)-14 Alkyl] trithiocarbonate (obtained according to the method of Example 1), after dissolving, add dropwise 2.6g of A monomer styrene, after fully pre-emulsification, add 0.0678g of the initiator potassium persulfate to dissolve, the water bath is heated to 70℃ Begin using a micro-injection pump to drop 5.9 g of B monomer hexafluorobutyl acrylate at a rate of 1.3 ml / h. After 6 hours of reaction, the system was cooled to room temperature and discharged. The obtained polymer emulsion has a pH value of 7, and it is milky white without demulsification and layering. It is still stable after 3 months. The conversion rate measured by the gravimetric method is 97.63%, the number average molecular weight of the product is 65503, and the molecular weight distribution is 1.36. image 3 It is a curve of the molecular weight and molecular weight dist...

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Abstract

The invention provides a method for preparing a gradient copolymer. In the method, based on the special chain transfer function and self-emulsification function of an amphiphilic reversible addition fragmentation chain transfer agent (amphiphilic RAFT reagent), under a condition of no emulsifier, the gradient copolymer is made from comonomer units by using a thermolysis initiator for initiation and water as a disperse phase and spontaneously by adopting a once feed method when the reactivity ratio of comonomers is high or forcefully by adopting a reaction material supply method when the polymerization reactivity ratio of the two comonomers is small. The molecular chain of the copolymer prepared by the method has a gradient, namely along a molecular chain, the leading position is gradually transferred from one monomer unit to the other monomer unit. The gradient copolymer is used in fields of gradient functional coatings, polymer bulking agents, damping materials and the like. The method is simple, low in cost and pollution free, and makes the control of a molecular chain structure and a polymerization process easy.

Description

Technical field [0001] The present invention relates to the field of polymer chemistry and emulsion polymerization, and in particular to a method of soap-free emulsion polymerization using RAFT (reversible addition-fragmentation chain transfer) to prepare gradient copolymers, the molecular chains of which are in gradient structure. Background technique [0002] Gradient copolymer is a new type of copolymer composed of A and B monomer units. With the increase of molecular weight, the monomer composition gradually changes from A monomer unit dominating to B monomer unit dominating along the main chain. status. The gradient of the molecular chain unit structure of the gradient copolymer makes the distribution of the link points of this new type of polymer more uniform, which can effectively increase the compatibility of the phase interface. Therefore, compared with random, block and alternating copolymers, gradient copolymers are used as A new type of polymer can combine the advant...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F2/22C08F2/38C07C329/00C09D201/00C08L101/00
Inventor 陈艳军周辉王艺峰罗文李明张超灿
Owner WUHAN UNIV OF TECH
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