Fluorescence Study of Fılm Formatıon From Hard/ Soft Latex Blends

Abstract

The effects of blend composition on film formation is studied using the SSF and UV-visible (UVV) techniques. Latex blend films were prepared from mixtures of two types of particles in dispersion, one composed of a high-T g (hard) pyrene (P) labeled polystyrene (PS) latex; the other a low-T g (soft) poly(n-butyl acrylate) (BuA1). Twelve different blend films were prepared in various hard/soft latex compositions at room temperature and annealed at elevated temperatures above glass transition temperature (T g ) of polystyerene for 10 min. Fluorescence intensity (I P ) from P was measured after each annealing step to monitor the stages of film formation. The evolution of transparency of latex films was monitored using photon transmission intensity, I tr . Film morphologies were examined by atomic force microscopy (AFM). The results showed that as the amount of hard component in the blend is decreased, a significant change occured in both I P and I tr curves at a certain critical weight fraction (50%wt) of PS hard latex. Above this fraction two distinct film formation stages, which are named as void closure and interdiffusion were seen in fluorescence data. However, below 50%wt PS no film formation stages were observed. Below this fraction, I tr data showed that phase separation process occurs between PS and BuA1 polymers. These results were also confirmed by AFM pictures. Film formation stages for 50-100%wt range of PS were modeled and related activation energies were calculated. There was no observable change in activation energies confirming that film formation behavior is not affected by varying the blend composition.

In Situ Observation of Tensile Deformation Processes of Soft Colloidal Crystalline Latex Fibers

“…[4][5][6][7][8] The film formation processes of hard or soft colloidal particles have been widely studied using microscopic and spectroscopic techniques. [9][10][11][12][13][14][15] However, relatively few studies dealt with the deformation mechanisms of polymer latex films with respect to its microstructure evolution under macroscopic stress. The deformation of hybrid films filled with inorganic nanoparticles has been studied.…”

“…The film formation processes of hard or soft colloidal particles have been widely studied using microscopic and spectroscopic techniques. − However, relatively few studies dealt with the deformation mechanisms of polymer latex films with respect to its microstructure evolution under macroscopic stress. The deformation of hybrid films filled with inorganic nanoparticles has been studied. − A theoretical model was presented based on experiments using small-angle neutron scattering (SANS). , The deformation mechanism of these composite films, containing silica nanoparticles, was dependent on the pH value of the latex dispersions, the silica volume fraction and the size of silica particles .…”

Kızılötesi Isıtma ile Polistiren Latekslerin Polimer Kompozit Filmlerindeki Film Oluşumuna Etkisi

“…Bu aşamada sınırlar kalkmış olur ve karşılıklı zincir geçişleri başlar. Latekslerden film oluşumunu açıklamak için literatür de birçok farklı çalışma türleri mevcuttur: elektron [7] atomik kuvvet mikroskop [8], nötron saçılması [9], ışımasız enerji transferi [10] ve kararlı durum floresans (SSF) [11]. Elipsometri [12], foton geçirgenliği (PT) [13][14][15] yansıma [16] taramalı elektron mikroskop (SEM) [17], [18][19][20] elektron mikroskopları ve lateks sistemlerinin karakterizasyonu ile ilgili çalışmalar sunulmuştur.…”

Soft core–hard shell latex particles for mechanically strong VOC‐free polymer films

“…However, the film formation process from a latex blend is not trivial with stratification often occurring depending on the particle size ratio and volume fractions of the two populations . While in certain cases stratification can be attractive, such as in the production of multilayer coatings, in many cases, homogeneous films are desired and phase separation can lead to an unwanted decrease in the physical properties of the resulting films …”