Synthesis and characterization of model carboxylated latexes for studies of film formation from latex blends

Abstract

Poly(n-butyl methacylate-co-n-butyl acylate) [P(BMA/BA)] soft latexes (carboxylated and noncarboxylated) were synthesized using a semicontinuous emulsion polymerization process that was designed on the basis of a theoretical calculation to determine the suitable surfactant [i.e., sodium dodecyl sulfate (SDS)], monomer, and water feed rates to maintain a constant particle number throughout the polymerization (guaranteeing monodispersity in the particle size), to obtain a homogeneous copolymer composition, and to independently control the particle size and carboxyl group concentration. The experimental results support the theoretical calculation. The surface coverage of the carboxyl groups present on the soft latex particles ranges from 7.6 to 21.9% for a series of latexes with particle sizes around 120 nm. In another series of latexes, the particle size was varied over a range from 120 to 450 nm. Monodisperse carboxylated polystyrene hard latexes were synthesized by shot growth (batch) and semicontinuous processes. The shot growth method is somewhat inflexible in providing more choices in surfactant, particle size, and surface carboxyl coverage. A semicontinuous process designed using a similar method used for the synthesis of P(BMA/BA) latexes successfully eliminated the drawbacks of the shot growth process. In this way, the changes in the surface carboxyl coverage (varies from 0 to 77.2%) was independent of the particle size, which was precisely controlled by the amount of styrene fed under suitable styrene and SDS feed rates.

Influence of particle surface properties on film formation from precipitated calcium carbonate/latex blends

“…Unlike the PS/P(BMA/BA) latex blends studied in the previous publications,11, 12 which can usually be prepared by simply mixing two or more polymer latexes, the blend of PCC with P(BMA/BA) latex synthesized by the method published elsewhere8 always coagulated when they were simply mixed. Altering the surface characteristics of the P(BMA/BA) latex particles by increasing the pH, adding surfactant (SDS), or introducing carboxyl groups on the surface of the P(BMA/BA) latex particles failed to solve this problem.…”

“…Poly( n ‐butyl methacrylate‐ co ‐ n ‐butyl acrylate) [P(BMA/BA); carboxylated and noncarboxylated] latexes were synthesized using a monomer‐starved semicontinuous emulsion polymerization process 8. A 500‐mL four‐neck flask with an attached reflux condenser and nitrogen gas inlet tube was used to perform all syntheses.…”

Flow properties of unvulcanised natural rubber/carboxylated styrene butadiene rubber latices and their blends

“…The carboxylation of synthetic latices like styrene–butadiene rubber will impart desirable mechanical or optical properties. The blending of hard and soft latex particles is an attractive strategy to develop new durable coatings with very good mechanical properties, and with zero volatile organic compounds 16. It is envisioned that the latex with low T g will deform and form a continuous film with embedded high T g latex particles, whose presence will impart desirable mechanical or optical properties 17–19.…”

Mechanical properties of films prepared from model high‐glass‐transition‐temperature/low‐glass‐transition‐temperature latex blends

“…Sodium dodecyl sulfate (SDS; Fisher Scientific; reagent grade) and potassium persulfate (KPS; Aldrich, Pittsburgh, PA; reagent grade) were used as received. Carboxylated and noncarboxylated high‐ T g PS and noncarboxylated low‐ T g poly( n ‐butyl methacrylate‐co‐ n ‐butyl acrylate) [P(BMA/BA)] model latex particles were synthesized, cleaned, and characterized according to methods published earlier 19. The characteristics of the latex particles used for the work described in this article are listed in Table I.…”

“…Films were cast from latex blends consisting of cleaned PS and P(BMA/BA) latex particles (PS = 0–60 vol %) to eliminate any possible influence of water‐soluble oligomers, surfactant, or other additives on the properties of the resulting films. A previous publication described the cleaning process 19. For the films used for mechanical tests, an initial solids content of 6 wt % was used, and the latex blends were dried under controlled conditions (temperature = 22 ± 0.5°C; relative humidity = 50 ± 0.5%) on poly(vinyl fluoride) films (Tedlar; DuPont, Wilmington, DE) for 10 days.…”