1. A photoresist modelling system, comprising: a computer comprising a processor; a memory coupled to the processor and storing one or more program instructions executable by the processor to: provide one or more process parameters for a photolithography process to a mathematical model stored in the program instructions, the photolithography process being used to form a photoresist on a semiconductor wafer surface, wherein the photoresist comprises at least one blocked polymer, and wherein at least one of the process parameters comprises a blocked polymer concentration in the photoresist; implement the mathematical model for the photolithography process, wherein the mathematical model is used to model the photoresist formed on the semiconductor wafer surface using the photolithography process, wherein a blocked polymer concentration gradient equation is implemented into the mathematical model, and wherein the blocked polymer concentration gradient equation describes a concentration gradient of a blocked polymer in the photoresist being modelled by the mathematical model, the blocked polymer concentration gradient equation describing the concentration gradient of the blocked polymer as a function of distance from an interface of the photoresist and the semiconductor wafer surface, a fraction of concentration reduction, and a depth of the reduction; and assess the modelled photoresist profile of the photoresist being formed on the semiconductor wafer surface; and control a photoresist profile of the photoresist as it is being formed on the semiconductor wafer surface by adjusting one or more process parameters of the photolithography process based on the assessment of the modelled photoresist profile.