Positively charged Poly[2-(methacryloyloxy)ethyltrimethylammonium chloride〕 (PMTC)

which has been often used as cationic polymeric flocculants

was chosen to coacervate with acacia to form microcapsules.As a simulacrum of insect sex pheromone molecule

dodecanol was used as the core material in this study.PMTC was prepared by polymerizing monomer ［2-(methacryloyloxy)ethyltrimethylammonium chloride] (MTC) with 2

2′-azobis(2-methylpropionamide) dihydro-chloride as initiator at 70℃.Complex coacervation of PMTC and acacia was optimized by varying experimental conditions

i.e. PMTC to acacia ratio

total polymer concentration and ionic strength etc. It was observed that maximum complex coacervation yield of 90% could be achieved with polymer concentration of 4% and the acacia/PMTC mass ratio of 3.22.Coacervation temperature and the order of polyelectolite solution addition (i.e. acacia added into PMTC solution or inversely) had no important effect on coacervation yield.Complex coacervation was partially suppressed by addition of sodium chloride.The optimized system was used for the encapsulation of dodecanol with different wall/core ratios.The microcapsules of size around a few microns were prepared.Good agreement was observed between the capsule size determined by optical microscope and that by light scattering.It was found that increasing wall/core ratio would cause a reduced dodecanol loading in the capsules.With 4 wt% wall material concentration

this loading declined from 4.98% with wall/core ratio at 8/1 to 3.07% with wall/core ration 12/1; and a very similar variation in dodecanol loading was seen with 5 wt% wall material concentration.Whereas the encapsulation rate of dodecanol

being 38% and 41% with 4 wt% and 5 wt% wall material concentration

respectively

at low wall/core ratio (8/1 to 9/1); this rate was reduced to about 33% with increase in wall/core ration to 12/1 regardless of the wall material concentration. The release behavior of dodecanol from the capsules was also changed due to different dodecanol loading.With reducing the amount of dodecanol added in the preparation

i.e. with increasing the wall/core ratio

the rate of dodecanol release rate was regularly decreased

a minimum release rate was detected in capsules prepared with wall/core ration at 12/1. As a general observation

a relatively rapid release was observed during the first 20 days

followed by a slower release rate for all the samples.Regardless of the wall material concentration

capsules with dodecanol loading below 4 wt% reached their final release around 20 days when incubated at 30℃ with constant relative humidity (50%)

while those with 5 wt% loading remained active even after 60 days under the same experimental conditions.