Initially, when APTES was treated with glutaraldehyde, red colouration was observed. Then similar test was carried out with APTES and glutaraldehyde second time but the colouration was yellow. Why different color appeared with same reaction?
, although I'm not an expert in this, I know that the reaction of APTES with glutaraldehyde has eben studied and utilized frequently. However, glutaraldehyde is a dialdehyde with two –CHO functional groups. Thus my personal guess is that the different colors are the result of either 1:1 or 1:2 reactions, i.e. whether one or two C=N bonds are formed.