Preparation and characterization of telechelic poly(methyl methacrylate). 1. Anionic polymerization with an initiator derived from 4-[2-(tert-butyldimethylsiloxy)ethyl]-.alpha.-methylstyrene

Abstract

Telechelic poly(methy1 methacrylate) having a terminal OH and COOH group was prepared by anionic polymerization with the initiator made by the reaction between 4-[2-(tert-butyldimethylsiloxy)-ethyl]-a-methylstyrene and n-butyllithium, followed by termination with carbon dioxide and hydrolysis of the tert-butyldimethylsiloxy group. The resulting polymer was characterized by osmometry, GPC, lH NMR, and potentiometric titration. It was confirmed that the polymer was pure and had a fairly narrow molecular weight distribution. IntroductionAcryl polymers such as poly(methy1 methacrylate) [abbreviated poly(MMA)l have been used widely as resin for paint and varnish. This is because the polymers have high weathering resistance and high transparency. Now, solvent-based paint is being replaced with a solvent-free powder 0ne,~,3 since organic solvents cause the serious problem of air pollution. The important factors of powder paints are the pour point and the glass-transition temperature of the resin, both of which depend on molecular eight.^^^ Hence the polymers for powder paint should have narrow molecular weight distributions. To obtain a hard coating, we need polymers having reactive groups. In particular, a,w-difunctional polymers, so-called telechelic polymers, are effective, since they can form a network structure through end-cross-linking.The present objective is to prepare telechelic poly-(MMA) having as narrow a molecular weight distribution as possible. We think the best way is to carry out an anionic polymerization of MMA using an initiator having a protected functional group followed by functional termination.697 There are scarcely any reports on preparation of telechelic poly( MMA), though numerous telechelic polymers have been in~estigated.~-l~ It is well-known that anionic initiators such as n-butyllithium (n-BuLi) make an attack not only on the vinyl group of MMA but also on the ester group.15J6 The latter, unfavorable side-reaction is suppressed by using bulky carbanion instead of small ne.^^-^^ It is very interesting that the addition of lithium chloride has a beneficial effect on the living character of the poly(methy1 methacrylate) anion.21 From a practical point of view, however, this method may be unprofitable for our purpose, since it is not so easy to remove the added salt from the resulting polymer-salt mixture, and the residual salt, especially chlorine, may have an adverse influence upon coating. Incidentally, the a-methylstyrene derivative can be quantitatively metalized by alkyllithium through equilibrium oligomerization near or above the ceiling temperature.22-28 It is relatively easy to purify monomers of the a-methylstyrene type because of their low ability to undergo thermal polymerization.28 The tert-butyldimethylsilyl group has been found to be effective for the protection of the hydroxyl group in anionic polymerizati~n.~~ Taking

Living Anionic Polymerization of 4‐(1‐Adamantyl)‐α‐Methylstyrene

“…The anionic polymerization system of α‐methylstyrenes usually shows equilibrium behaviors known as the thermodynamically reversible polymerization due to the steric strain caused by the α‐methyl group . The polymerization of AdαMS was first carried out with K‐Naph in THF at −78 °C for 8 h in order to achieve the complete consumption of monomer similar to the previous experiment (run 5).…”

“…In this study, we newly designed and anionically polymerized an adamantyl‐substituted α‐methylstyrene derivative, 4‐(1‐adamantyl)‐α‐methylstyrene ( AdαMS ), in order to check the polymerizability of the monomer and the thermal properties of the resulting polymer. It is well known that α‐methylstyrene derivatives usually undergo the equilibrium polymerization under the anionic conditions due to the low ceiling temperatures . The polymerization and depolymerization of α‐methylstyrene derivatives reversibly occur under the equilibrium conditions.…”

“…The anionic polymerization system of α-methylstyrenes usually shows equilibrium behaviors known as the thermodynamically reversible polymerization due to the steric strain caused by the α-methyl group. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] The polymerization of AdαMS was first carried out with K-Naph in THF at −78 °C for 8 h in order to achieve the complete consumption of monomer similar to the previous experiment (run 5). Then, the polymerization temperature of the system was raised to room temperature and the system was stood for 20 h. The characteristic red color of the polymerization system was maintained at room temperature until the termination with methanol.…”

“…It is well known that α-methylstyrene derivatives usually undergo the equilibrium polymerization under the anionic conditions due to the low ceiling temperatures. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] The polymerization and depolymerization of α-methylstyrene derivatives reversibly occur under the equilibrium conditions. In addition, the poly(α-methylstyrene)s generally show higher T g values than those of the corresponding polystyrene derivatives and the ease of the chain degradation on heating.…”

Synthesis of Syndiotactic Macrocyclic Poly(methyl methacrylate) via Transformation of the Growing Terminal in Stereospecific Anionic Polymerization

“…It is known that the syndiospecific anionic polymerization of MMA proceeds with lithium cation as the counterion in polar solvents like THF at a lower temperature, in which a lithium‐based nucleophile like 1,1‐diphenylhexyl lithium prepared by the 1:1 addition of butyl lithium to 1,1‐dipehnylethylene has been employed as the initiator . Herein, we first examined the synthesis of syndiotactic PMMA with an alkyne terminal using a lithium enolate initiator bearing a protected alkyne.…”