Alkyl methacrylates glass transitions

Various substituted styrene-alkyl methacrylate block copolymers and all-acrylic block copolymers have been synthesized in a controlled fashion demonstrating predictable molecular weight and narrow molecular weight distributions. Table I depicts various poly (t-butylstyrene)-b-poly(t-butyl methacrylate) (PTBS-PTBMA) and poly(methyl methacrylate)-b-poly(t-butyl methacrylate) (PMMA-PTBMA) samples. In addition, all-acrylic block copolymers based on poly(2-ethylhexyl methacrylate)-b-poly(t-butyl methacrylate) have been recently synthesized and offer many unique possibilities due to the low glass transition temperature of PEHMA. In most cases, a range of 5-25 wt.% of alkyl methacrylate was incorporated into the block copolymer. This composition not only facilitated solubility during subsequent hydrolysis but also limited the maximum level of derived ionic functionality. 

Rogers, S. S., and L. Mandelkern Glass formation in polymers. I. The glass transitions of the poly(n-alkyl methacrylates). J. Phys. Chem. 61, 985—990 (1957). 

A theoretical derivation based on the Gibbs-Di Marzio (1958) theory of the glass transition leads to the conclusion that for the series of poly(alkyl methacrylates)... 

Malhotra, B.D., Pethrick, R.A. (1983) Positron annihilation studies of the glass-rubber transition in Poly(alkyl methacrylate). Macromolecules 16, 1175. 

It is apparent that the conjunct roles of ester group and 8 "Backbone substituents are important in determination of the extent to which backbone segments experience mobility as the glass transition is approached. In this respect the influence of tacticity in 1,1-disubstituted alkyl methacrylate polymers requires investigation. 

Tg-Alkyl-MA.TXT 5-2 Glass transition temperatures (Tg) of poly(alkyl methacrylates) P. Peyser Glass Transition Temperatures of Polymers, in Polymer Handbook, 3rd ed., J. Brandrup and E. Immergut eds., Wiley Interscience, New York, pp. VI209-VI277... 

More recently, a similar photochromic behavior was observed by Eisenbach32,33) for the cis-trans isomerization of azobenzene residues attached as side groups to copolymers when examined below their glass transition temperature. These copolymers were obtained by copolymerization of the monomers 4-methacryloylaminoazobenzene (TV) and 4-(3-methaeryloyloxybutylcarbonylamino)azobenzene (V) with various alkyl acrylates and methacrylates. 

Figure 2. Platelet retention by polyalkyl acrylates and by polyalkyl methacrylates plotted vs length of the alkyl side chain (A) or glass transition temperature, Tg (B). (Replotted from data in Fig. 3 of Ref. 17.)...

R 624 M. Wind, R. Graf, A. Heuer and H. W. Spiess, Structural Relaxation of Polymers at the Glass Transition Conformational Memory in Poly(n-Alkyl Methacrylates) , Phys. Rev. Lett., 2003,91,155702 R 625 J. -L. Wolfender, K. Ndjoko and K. Hostettmann, Liquid Chromatography with Ultraviolet Absorbance-Mass Spectrometric Detection and with Nuclear Magnetic Resonance Spectrometry A Powerful Combination for the On-Line Structural Investigation of Plant Metabolites , J. Chromatogr., A, 2003,1000,437... 

Figure 10-24. Glass transition temperatures Tc or brittleness temperatures Tb for poly(alkyl methacrylates) with the monomeric unit -(-CH2—C(CH3)(COO(CH2)nH)-)-.

Hempel, E., Kahle, S., Unger, R and Donth, E. (1999) Systematic calorimetric study of glass transition in the homologous series of poly(n-alkyl methacrylate)s Narayanaswamy parameters in the crossover region. Ther-mochimica Acta, 329, 97-108. 

TABLE 13.1. Glass-transition and secondary-relaxation temperatures ofpoly(alkyl acrylates) andpoly(alkyl methacrylates). 

Figure 5. Glass transition temperature, Tg, versus side arm length for the norbornene linear polymers in comparison with alkyl methacrylates.

This paper reports on the synthesis, characterisation, and applications of novel flame retardant dibromostyrene-based latexes. They are copolymers of dibromostyrene with butadiene, alkyl acrylates and methacrylates, vinyl acetate, styrene and unsaturated carboxylic acids, which form a wide variety of flame retardant latexes via an emulsion polymerisation technique. Choice of monomer or monomer blend is based upon the final glass transition temperature of the copolymer desired. Other criteria include desired physical properties and chemical resistance. Dibromostyrene-based butadiene and acryUc latexes are shown to possess the desired physical properties for use in coatings, adhesives and sealants, and the bromine content of the latexes has enabled the material to pass six different flammability requirements for the end uses such as textile backcoating, latex-based paint, contact adhesive, latex sealant, nonwoven binder, and carpet backing. 18 refs. 

As expected, the influence of flexible side groups is different from that of rigid substituents. The increase in length of the flexible alkyl sidechains (e.g., in acrylates or methacrylates and polystyrene) causes the glass transition temperature to decrease (Mark et al. 1993 Gedde 2001). 

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