SYNOPSISFour types of emulsion copolymerization processes were applied to produce various styrenemethyl acrylate copolymer latices. (1) Batch emulsion copolymerization. ( 2 ) Monomer starved semicontinuous emulsion copolymerization, i.e., a monomer mixture of constant composition was fed to the reactor at a constant rate. Sufficiently low addition rates led to homogeneous copolymers. ( 3 ) Optimal addition rate profiles were used to produce homogeneous emulsion copolymers in relatively short times. The profiles were determined in a semiempirical way, and applied to three different copolymer compositions. ( 4 ) We made an attempt to determine an addition rate profile to produce a heterogeneous emulsion copolymer with predetermined heterogeneity, i.e., a copolymer of which the chemical composition distribution (CCD) did not consist of one narrow peak, as with homogeneous copolymers, but had a predetermined broadness profile. Strategies ( 2 ) and (3) were used to produce homogeneous emulsion copolymers with varying fractions of styrene. Strategy (3) was also used to demonstrate the influence of the monomer ratio on the kinetics. The advantage of this method is that the monomer ratio is constant over the whole conversion range in the latex particles. High performance liquid chromatography (HPLC) was used to determine the homogeneity/ heterogeneity of the copolymers produced, and proved to be invaluable in determining the optimal addition rate profile. The final goal will be to study the influence of the chemical composition distribution (CCD) on mechanical properties of these copolymers, as both homopolymers used in this study have quite differentglass transition temperatures; the results will be published later. 0 1993 John Wiley & Sons, Inc.

. (1995). The effect of composition drift and copolymer microstructure on mechanical bulk properties of styrene-methyl acrylate emulsion copolymers. Macromolecular Symposia, 92, 133-156. DOI: 10.1002/masy.19950920113 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Macromol. Symp. 92, 133-156 (1995) Abstract: In order to determine thc inÍ'luencc of composition driÍt and copolymer microstructure on the mcchanical bulk propcrties of styrcnemethyl acrylate oopolymers, scveral copolymers were produced by emulsion copolymerizalion.'l'hree diÍíerent average compositions were used. By pcrlbrming 1he copolyn.rcrizations under batch and scmicontinuous conditions with two diÍferent monomor addition strategies (starvcd conditions and optimal addition) it was possible to control composition drilt and to produce copolymers with differcnt microstructures (chcmical composition distributions). All these oopolymers were processed in a way that ensured that the original particle structure was lost belbre the polymers wcre tested. It was Íbund that composition driÍ1 had an inÍluenos on the mcchanical properties (Young's modulus, maximum stress' clongation at break). This influencc could be undcrstood vcry well on the basis of prcscnt knowlcdge about structure-mechanical properties rclationships. In thc case of homogeneous copolymers maximum stress and elongation at break arc depcndent on thc moleoular weight, and only wcakly depcndent on the chemioal composition, and Young's modulus is indepcndent of chemical composition and molecular wcight irr the rangc of compositions investigated, as expected. ln the case of heterogeneous copolymers' thc inÍluence of copolymer microstructure on Young's modulus, maximum stress and elongation at break is very large. Depending on the extent of control of composition driÍï during the polymerizations, phase separation was observed in the processed polymers, and the presencc of a rubber phase affected the properties profoundlY.